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2022-04-06x86/compressed: Register GHCB memory when SEV-SNP is activeBrijesh Singh1-0/+4
The SEV-SNP guest is required by the GHCB spec to register the GHCB's Guest Physical Address (GPA). This is because the hypervisor may prefer that a guest use a consistent and/or specific GPA for the GHCB associated with a vCPU. For more information, see the GHCB specification section "GHCB GPA Registration". If hypervisor can not work with the guest provided GPA then terminate the guest boot. Signed-off-by: Brijesh Singh <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Venu Busireddy <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2022-04-06x86/compressed: Add helper for validating pages in the decompression stageBrijesh Singh3-1/+67
Many of the integrity guarantees of SEV-SNP are enforced through the Reverse Map Table (RMP). Each RMP entry contains the GPA at which a particular page of DRAM should be mapped. The VMs can request the hypervisor to add pages in the RMP table via the Page State Change VMGEXIT defined in the GHCB specification. Inside each RMP entry is a Validated flag; this flag is automatically cleared to 0 by the CPU hardware when a new RMP entry is created for a guest. Each VM page can be either validated or invalidated, as indicated by the Validated flag in the RMP entry. Memory access to a private page that is not validated generates a #VC. A VM must use the PVALIDATE instruction to validate a private page before using it. To maintain the security guarantee of SEV-SNP guests, when transitioning pages from private to shared, the guest must invalidate the pages before asking the hypervisor to change the page state to shared in the RMP table. After the pages are mapped private in the page table, the guest must issue a page state change VMGEXIT to mark the pages private in the RMP table and validate them. Upon boot, BIOS should have validated the entire system memory. During the kernel decompression stage, early_setup_ghcb() uses set_page_decrypted() to make the GHCB page shared (i.e. clear encryption attribute). And while exiting from the decompression, it calls set_page_encrypted() to make the page private. Add snp_set_page_{private,shared}() helpers that are used by set_page_{decrypted,encrypted}() to change the page state in the RMP table. [ bp: Massage commit message and comments. ] Signed-off-by: Brijesh Singh <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2022-04-06x86/sev: Check the VMPL levelBrijesh Singh1-2/+26
The Virtual Machine Privilege Level (VMPL) feature in the SEV-SNP architecture allows a guest VM to divide its address space into four levels. The level can be used to provide hardware isolated abstraction layers within a VM. VMPL0 is the highest privilege level, and VMPL3 is the least privilege level. Certain operations must be done by the VMPL0 software, such as: * Validate or invalidate memory range (PVALIDATE instruction) * Allocate VMSA page (RMPADJUST instruction when VMSA=1) The initial SNP support requires that the guest kernel is running at VMPL0. Add such a check to verify the guest is running at level 0 before continuing the boot. There is no easy method to query the current VMPL level, so use the RMPADJUST instruction to determine whether the guest is running at the VMPL0. [ bp: Massage commit message. ] Signed-off-by: Brijesh Singh <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2022-04-06x86/sev: Check SEV-SNP features supportBrijesh Singh2-6/+32
Version 2 of the GHCB specification added the advertisement of features that are supported by the hypervisor. If the hypervisor supports SEV-SNP then it must set the SEV-SNP features bit to indicate that the base functionality is supported. Check that feature bit while establishing the GHCB; if failed, terminate the guest. Version 2 of the GHCB specification adds several new Non-Automatic Exits (NAEs), most of them are optional except the hypervisor feature. Now that the hypervisor feature NAE is implemented, bump the GHCB maximum supported protocol version. While at it, move the GHCB protocol negotiation check from the #VC exception handler to sev_enable() so that all feature detection happens before the first #VC exception. While at it, document why the GHCB page cannot be setup from load_stage2_idt(). [ bp: Massage commit message. ] Signed-off-by: Brijesh Singh <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2022-04-06x86/sev: Define the Linux-specific guest termination reasonsBrijesh Singh1-3/+3
The GHCB specification defines the reason code for reason set 0. The reason codes defined in the set 0 do not cover all possible causes for a guest to request termination. The reason sets 1 to 255 are reserved for the vendor-specific codes. Reserve the reason set 1 for the Linux guest. Define the error codes for reason set 1 so that one can have meaningful termination reasons and thus better guest failure diagnosis. While at it, change sev_es_terminate() to accept a reason set parameter. [ bp: Massage commit message. ] Signed-off-by: Brijesh Singh <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Venu Busireddy <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2022-04-06x86/compressed/64: Detect/setup SEV/SME features earlier during bootMichael Roth4-53/+60
With upcoming SEV-SNP support, SEV-related features need to be initialized earlier during boot, at the same point the initial #VC handler is set up, so that the SEV-SNP CPUID table can be utilized during the initial feature checks. Also, SEV-SNP feature detection will rely on EFI helper functions to scan the EFI config table for the Confidential Computing blob, and so would need to be implemented at least partially in C. Currently set_sev_encryption_mask() is used to initialize the sev_status and sme_me_mask globals that advertise what SEV/SME features are available in a guest. Rename it to sev_enable() to better reflect that (SME is only enabled in the case of SEV guests in the boot/compressed kernel), and move it to just after the stage1 #VC handler is set up so that it can be used to initialize SEV-SNP as well in future patches. While at it, re-implement it as C code so that all SEV feature detection can be better consolidated with upcoming SEV-SNP feature detection, which will also be in C. The 32-bit entry path remains unchanged, as it never relied on the set_sev_encryption_mask() initialization to begin with. [ bp: Massage commit message. ] Signed-off-by: Michael Roth <[email protected]> Signed-off-by: Brijesh Singh <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2022-04-06x86/boot: Use MSR read/write helpers instead of inline assemblyMichael Roth1-10/+7
Update all C code to use the new boot_rdmsr()/boot_wrmsr() helpers instead of relying on inline assembly. Suggested-by: Borislav Petkov <[email protected]> Signed-off-by: Michael Roth <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2022-03-26Merge tag 'memcpy-v5.18-rc1' of ↵Linus Torvalds1-1/+2
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull FORTIFY_SOURCE updates from Kees Cook: "This series consists of two halves: - strict compile-time buffer size checking under FORTIFY_SOURCE for the memcpy()-family of functions (for extensive details and rationale, see the first commit) - enabling FORTIFY_SOURCE for Clang, which has had many overlapping bugs that we've finally worked past" * tag 'memcpy-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: fortify: Add Clang support fortify: Make sure strlen() may still be used as a constant expression fortify: Use __diagnose_as() for better diagnostic coverage fortify: Make pointer arguments const Compiler Attributes: Add __diagnose_as for Clang Compiler Attributes: Add __overloadable for Clang Compiler Attributes: Add __pass_object_size for Clang fortify: Replace open-coded __gnu_inline attribute fortify: Update compile-time tests for Clang 14 fortify: Detect struct member overflows in memset() at compile-time fortify: Detect struct member overflows in memmove() at compile-time fortify: Detect struct member overflows in memcpy() at compile-time
2022-02-22x86: clean up symbol aliasingMark Rutland2-4/+2
Now that we have SYM_FUNC_ALIAS() and SYM_FUNC_ALIAS_WEAK(), use those to simplify the definition of function aliases across arch/x86. For clarity, where there are multiple annotations such as EXPORT_SYMBOL(), I've tried to keep annotations grouped by symbol. For example, where a function has a name and an alias which are both exported, this is organised as: SYM_FUNC_START(func) ... asm insns ... SYM_FUNC_END(func) EXPORT_SYMBOL(func) SYM_FUNC_ALIAS(alias, func) EXPORT_SYMBOL(alias) Where there are only aliases and no exports or other annotations, I have not bothered with line spacing, e.g. SYM_FUNC_START(func) ... asm insns ... SYM_FUNC_END(func) SYM_FUNC_ALIAS(alias, func) The tools/perf/ copies of memset_64.S and memset_64.S are updated likewise to avoid the build system complaining these are mismatched: | Warning: Kernel ABI header at 'tools/arch/x86/lib/memcpy_64.S' differs from latest version at 'arch/x86/lib/memcpy_64.S' | diff -u tools/arch/x86/lib/memcpy_64.S arch/x86/lib/memcpy_64.S | Warning: Kernel ABI header at 'tools/arch/x86/lib/memset_64.S' differs from latest version at 'arch/x86/lib/memset_64.S' | diff -u tools/arch/x86/lib/memset_64.S arch/x86/lib/memset_64.S There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <[email protected]> Acked-by: Ard Biesheuvel <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Acked-by: Mark Brown <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Jiri Slaby <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Will Deacon <[email protected]>
2022-02-13fortify: Detect struct member overflows in memmove() at compile-timeKees Cook1-1/+2
As done for memcpy(), also update memmove() to use the same tightened compile-time checks under CONFIG_FORTIFY_SOURCE. Signed-off-by: Kees Cook <[email protected]>
2022-01-19Merge tag 'kbuild-v5.17' of ↵Linus Torvalds1-6/+6
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - Add new kconfig target 'make mod2noconfig', which will be useful to speed up the build and test iteration. - Raise the minimum supported version of LLVM to 11.0.0 - Refactor certs/Makefile - Change the format of include/config/auto.conf to stop double-quoting string type CONFIG options. - Fix ARCH=sh builds in dash - Separate compression macros for general purposes (cmd_bzip2 etc.) and the ones for decompressors (cmd_bzip2_with_size etc.) - Misc Makefile cleanups * tag 'kbuild-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits) kbuild: add cmd_file_size arch: decompressor: remove useless vmlinux.bin.all-y kbuild: rename cmd_{bzip2,lzma,lzo,lz4,xzkern,zstd22} kbuild: drop $(size_append) from cmd_zstd sh: rename suffix-y to suffix_y doc: kbuild: fix default in `imply` table microblaze: use built-in function to get CPU_{MAJOR,MINOR,REV} certs: move scripts/extract-cert to certs/ kbuild: do not quote string values in include/config/auto.conf kbuild: do not include include/config/auto.conf from shell scripts certs: simplify $(srctree)/ handling and remove config_filename macro kbuild: stop using config_filename in scripts/Makefile.modsign certs: remove misleading comments about GCC PR certs: refactor file cleaning certs: remove unneeded -I$(srctree) option for system_certificates.o certs: unify duplicated cmd_extract_certs and improve the log certs: use $< and $@ to simplify the key generation rule kbuild: remove headers_check stub kbuild: move headers_check.pl to usr/include/ certs: use if_changed to re-generate the key when the key type is changed ...
2022-01-14kbuild: rename cmd_{bzip2,lzma,lzo,lz4,xzkern,zstd22}Masahiro Yamada1-6/+6
GZIP-compressed files end with 4 byte data that represents the size of the original input. The decompressors (the self-extracting kernel) exploit it to know the vmlinux size beforehand. To mimic the GZIP's trailer, Kbuild provides cmd_{bzip2,lzma,lzo,lz4,xzkern,zstd22}. Unfortunately these macros are used everywhere despite the appended size data is only useful for the decompressors. There is no guarantee that such hand-crafted trailers are safely ignored. In fact, the kernel refuses compressed initramdfs with the garbage data. That is why usr/Makefile overrides size_append to make it no-op. To limit the use of such broken compressed files, this commit renames the existing macros as follows: cmd_bzip2 --> cmd_bzip2_with_size cmd_lzma --> cmd_lzma_with_size cmd_lzo --> cmd_lzo_with_size cmd_lz4 --> cmd_lz4_with_size cmd_xzkern --> cmd_xzkern_with_size cmd_zstd22 --> cmd_zstd22_with_size To keep the decompressors working, I updated the following Makefiles accordingly: arch/arm/boot/compressed/Makefile arch/h8300/boot/compressed/Makefile arch/mips/boot/compressed/Makefile arch/parisc/boot/compressed/Makefile arch/s390/boot/compressed/Makefile arch/sh/boot/compressed/Makefile arch/x86/boot/compressed/Makefile I reused the current macro names for the normal usecases; they produce the compressed data in the proper format. I did not touch the following: arch/arc/boot/Makefile arch/arm64/boot/Makefile arch/csky/boot/Makefile arch/mips/boot/Makefile arch/riscv/boot/Makefile arch/sh/boot/Makefile kernel/Makefile This means those Makefiles will stop appending the size data. I dropped the 'override size_append' hack from usr/Makefile. Signed-off-by: Masahiro Yamada <[email protected]> Reviewed-by: Nicolas Schier <[email protected]>
2022-01-12Merge tag 'x86_core_for_v5.17_rc1' of ↵Linus Torvalds3-8/+8
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 core updates from Borislav Petkov: - Get rid of all the .fixup sections because this generates misleading/wrong stacktraces and confuse RELIABLE_STACKTRACE and LIVEPATCH as the backtrace misses the function which is being fixed up. - Add Straight Line Speculation mitigation support which uses a new compiler switch -mharden-sls= which sticks an INT3 after a RET or an indirect branch in order to block speculation after them. Reportedly, CPUs do speculate behind such insns. - The usual set of cleanups and improvements * tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits) x86/entry_32: Fix segment exceptions objtool: Remove .fixup handling x86: Remove .fixup section x86/word-at-a-time: Remove .fixup usage x86/usercopy: Remove .fixup usage x86/usercopy_32: Simplify __copy_user_intel_nocache() x86/sgx: Remove .fixup usage x86/checksum_32: Remove .fixup usage x86/vmx: Remove .fixup usage x86/kvm: Remove .fixup usage x86/segment: Remove .fixup usage x86/fpu: Remove .fixup usage x86/xen: Remove .fixup usage x86/uaccess: Remove .fixup usage x86/futex: Remove .fixup usage x86/msr: Remove .fixup usage x86/extable: Extend extable functionality x86/entry_32: Remove .fixup usage x86/entry_64: Remove .fixup usage x86/copy_mc_64: Remove .fixup usage ...
2022-01-11Merge tag 'efi-next-for-v5.17' of ↵Linus Torvalds1-3/+11
git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi Pull EFI updates from Ard Biesheuvel: - support taking the measurement of the initrd when loaded via the LoadFile2 protocol - kobject API cleanup from Greg - some header file whitespace fixes * tag 'efi-next-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi: efi: use default_groups in kobj_type efi/libstub: measure loaded initrd info into the TPM efi/libstub: consolidate initrd handling across architectures efi/libstub: x86/mixed: increase supported argument count efi/libstub: add prototype of efi_tcg2_protocol::hash_log_extend_event() include/linux/efi.h: Remove unneeded whitespaces before tabs
2022-01-10Merge tag 'x86_build_for_v5.17_rc1' of ↵Linus Torvalds1-2/+5
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 build fix from Borislav Petkov: "A fix for cross-compiling the compressed stub on arm64 with clang" * tag 'x86_build_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/boot/compressed: Move CLANG_FLAGS to beginning of KBUILD_CFLAGS
2021-12-23x86/boot/compressed: Move CLANG_FLAGS to beginning of KBUILD_CFLAGSNathan Chancellor1-2/+5
When cross compiling i386_defconfig on an arm64 host with clang, there are a few instances of '-Waddress-of-packed-member' and '-Wgnu-variable-sized-type-not-at-end' in arch/x86/boot/compressed/, which should both be disabled with the cc-disable-warning calls in that directory's Makefile, which indicates that cc-disable-warning is failing at the point of testing these flags. The cc-disable-warning calls fail because at the point that the flags are tested, KBUILD_CFLAGS has '-march=i386' without $(CLANG_FLAGS), which has the '--target=' flag to tell clang what architecture it is targeting. Without the '--target=' flag, the host architecture (arm64) is used and i386 is not a valid value for '-march=' in that case. This error can be seen by adding some logging to try-run: clang-14: error: the clang compiler does not support '-march=i386' Invoking the compiler has to succeed prior to calling cc-option or cc-disable-warning in order to accurately test whether or not the flag is supported; if it doesn't, the requested flag can never be added to the compiler flags. Move $(CLANG_FLAGS) to the beginning of KBUILD_FLAGS so that any new flags that might be added in the future can be accurately tested. Fixes: d5cbd80e302d ("x86/boot: Add $(CLANG_FLAGS) to compressed KBUILD_CFLAGS") Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2021-12-08x86: Prepare asm files for straight-line-speculationPeter Zijlstra3-8/+8
Replace all ret/retq instructions with RET in preparation of making RET a macro. Since AS is case insensitive it's a big no-op without RET defined. find arch/x86/ -name \*.S | while read file do sed -i 's/\<ret[q]*\>/RET/' $file done Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2021-11-21efi/libstub: x86/mixed: increase supported argument countArd Biesheuvel1-3/+11
Increase the number of arguments supported by mixed mode calls, so that we will be able to call into the TCG2 protocol to measure the initrd and extend the associated PCR. This involves the TCG2 protocol's hash_log_extend_event() method, which takes five arguments, three of which are u64 and need to be split, producing a total of 8 outgoing Signed-off-by: Ard Biesheuvel <[email protected]> Signed-off-by: Ilias Apalodimas <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Ard Biesheuvel <[email protected]>
2021-11-15x86/sev: Shorten GHCB terminate macro namesBrijesh Singh1-3/+3
Shorten macro names for improved readability. Suggested-by: Borislav Petkov <[email protected]> Signed-off-by: Brijesh Singh <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Venu Busireddy <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-11-02Merge tag 'x86_core_for_v5.16_rc1' of ↵Linus Torvalds3-4/+5
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 core updates from Borislav Petkov: - Do not #GP on userspace use of CLI/STI but pretend it was a NOP to keep old userspace from breaking. Adjust the corresponding iopl selftest to that. - Improve stack overflow warnings to say which stack got overflowed and raise the exception stack sizes to 2 pages since overflowing the single page of exception stack is very easy to do nowadays with all the tracing machinery enabled. With that, rip out the custom mapping of AMD SEV's too. - A bunch of changes in preparation for FGKASLR like supporting more than 64K section headers in the relocs tool, correct ORC lookup table size to cover the whole kernel .text and other adjustments. * tag 'x86_core_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: selftests/x86/iopl: Adjust to the faked iopl CLI/STI usage vmlinux.lds.h: Have ORC lookup cover entire _etext - _stext x86/boot/compressed: Avoid duplicate malloc() implementations x86/boot: Allow a "silent" kaslr random byte fetch x86/tools/relocs: Support >64K section headers x86/sev: Make the #VC exception stacks part of the default stacks storage x86: Increase exception stack sizes x86/mm/64: Improve stack overflow warnings x86/iopl: Fake iopl(3) CLI/STI usage
2021-10-27x86/boot/compressed: Avoid duplicate malloc() implementationsKees Cook3-4/+5
The early malloc() and free() implementation in include/linux/decompress/mm.h (which is also included by the static decompressors) is static. This is fine when the only thing interested in using malloc() is the decompression code, but the x86 early boot environment may use malloc() in a couple places, leading to a potential collision when the static copies of the available memory region ("malloc_ptr") gets reset to the global "free_mem_ptr" value. As it happened, the existing usage pattern was accidentally safe because each user did 1 malloc() and 1 free() before returning and were not nested: extract_kernel() (misc.c) choose_random_location() (kaslr.c) mem_avoid_init() handle_mem_options() malloc() ... free() ... parse_elf() (misc.c) malloc() ... free() Once the future FGKASLR series is added, however, it will insert additional malloc() calls local to fgkaslr.c in the middle of parse_elf()'s malloc()/free() pair: parse_elf() (misc.c) malloc() if (...) { layout_randomized_image(output, &ehdr, phdrs); malloc() <- boom ... else layout_image(output, &ehdr, phdrs); free() To avoid collisions, there must be a single implementation of malloc(). Adjust include/linux/decompress/mm.h so that visibility can be controlled, provide prototypes in misc.h, and implement the functions in misc.c. This also results in a small size savings: $ size vmlinux.before vmlinux.after text data bss dec hex filename 8842314 468 178320 9021102 89a6ae vmlinux.before 8842240 468 178320 9021028 89a664 vmlinux.after Signed-off-by: Kees Cook <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2021-09-25lib/string: Move helper functions out of string.cKees Cook2-0/+4
The core functions of string.c are those that may be implemented by per-architecture functions, or overloaded by FORTIFY_SOURCE. As a result, it needs to be built with __NO_FORTIFY. Without this, macros will collide with function declarations. This was accidentally working due to -ffreestanding (on some architectures). Make this deterministic by explicitly setting __NO_FORTIFY and move all the helper functions into string_helpers.c so that they gain the fortification coverage they had been missing. Cc: Andrew Morton <[email protected]> Cc: Nick Desaulniers <[email protected]> Cc: Andy Lavr <[email protected]> Cc: Nathan Chancellor <[email protected]> Cc: Alexey Dobriyan <[email protected]> Cc: Stephen Rothwell <[email protected]> Cc: Bartosz Golaszewski <[email protected]> Acked-by: Andy Shevchenko <[email protected]> Signed-off-by: Kees Cook <[email protected]>
2021-08-30Merge tag 'x86_cleanups_for_v5.15' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cleanups from Borislav Petkov: "The usual round of minor cleanups and fixes" * tag 'x86_cleanups_for_v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/kaslr: Have process_mem_region() return a boolean x86/power: Fix kernel-doc warnings in cpu.c x86/mce/inject: Replace deprecated CPU-hotplug functions. x86/microcode: Replace deprecated CPU-hotplug functions. x86/mtrr: Replace deprecated CPU-hotplug functions. x86/mmiotrace: Replace deprecated CPU-hotplug functions.
2021-08-24x86/kaslr: Have process_mem_region() return a booleanJing Yangyang1-1/+1
Fix the following coccicheck warning: ./arch/x86/boot/compressed/kaslr.c:671:10-11:WARNING:return of 0/1 in function 'process_mem_region' with return type bool Generated by: scripts/coccinelle/misc/boolreturn.cocci Reported-by: Zeal Robot <[email protected]> Signed-off-by: Jing Yangyang <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-08-21x86/efi: Restore Firmware IDT before calling ExitBootServices()Joerg Roedel2-9/+24
Commit 79419e13e808 ("x86/boot/compressed/64: Setup IDT in startup_32 boot path") introduced an IDT into the 32-bit boot path of the decompressor stub. But the IDT is set up before ExitBootServices() is called, and some UEFI firmwares rely on their own IDT. Save the firmware IDT on boot and restore it before calling into EFI functions to fix boot failures introduced by above commit. Fixes: 79419e13e808 ("x86/boot/compressed/64: Setup IDT in startup_32 boot path") Reported-by: Fabio Aiuto <[email protected]> Signed-off-by: Joerg Roedel <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Acked-by: Ard Biesheuvel <[email protected]> Cc: [email protected] # 5.13+ Link: https://lkml.kernel.org/r/[email protected]
2021-05-12x86/boot/compressed: Enable -WundefNick Desaulniers3-2/+3
A discussion around -Wundef showed that there were still a few boolean Kconfigs where #if was used rather than #ifdef to guard different code. Kconfig doesn't define boolean configs, which can result in -Wundef warnings. arch/x86/boot/compressed/Makefile resets the CFLAGS used for this directory, and doesn't re-enable -Wundef as the top level Makefile does. If re-added, with RANDOMIZE_BASE and X86_NEED_RELOCS disabled, the following warnings are visible. arch/x86/boot/compressed/misc.h:82:5: warning: 'CONFIG_RANDOMIZE_BASE' is not defined, evaluates to 0 [-Wundef] ^ arch/x86/boot/compressed/misc.c:175:5: warning: 'CONFIG_X86_NEED_RELOCS' is not defined, evaluates to 0 [-Wundef] ^ Simply fix these and re-enable this warning for this directory. Suggested-by: Nathan Chancellor <[email protected]> Suggested-by: Joe Perches <[email protected]> Signed-off-by: Nick Desaulniers <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Acked-by: Kees Cook <[email protected]> Reviewed-by: Nathan Chancellor <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2021-05-10x86/sev-es: Rename sev-es.{ch} to sev.{ch}Brijesh Singh2-5/+5
SEV-SNP builds upon the SEV-ES functionality while adding new hardware protection. Version 2 of the GHCB specification adds new NAE events that are SEV-SNP specific. Rename the sev-es.{ch} to sev.{ch} so that all SEV* functionality can be consolidated in one place. Signed-off-by: Brijesh Singh <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Acked-by: Joerg Roedel <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-04-27Merge tag 'x86_core_for_v5.13' of ↵Linus Torvalds1-6/+5
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 updates from Borislav Petkov: - Turn the stack canary into a normal __percpu variable on 32-bit which gets rid of the LAZY_GS stuff and a lot of code. - Add an insn_decode() API which all users of the instruction decoder should preferrably use. Its goal is to keep the details of the instruction decoder away from its users and simplify and streamline how one decodes insns in the kernel. Convert its users to it. - kprobes improvements and fixes - Set the maximum DIE per package variable on Hygon - Rip out the dynamic NOP selection and simplify all the machinery around selecting NOPs. Use the simplified NOPs in objtool now too. - Add Xeon Sapphire Rapids to list of CPUs that support PPIN - Simplify the retpolines by folding the entire thing into an alternative now that objtool can handle alternatives with stack ops. Then, have objtool rewrite the call to the retpoline with the alternative which then will get patched at boot time. - Document Intel uarch per models in intel-family.h - Make Sub-NUMA Clustering topology the default and Cluster-on-Die the exception on Intel. * tag 'x86_core_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits) x86, sched: Treat Intel SNC topology as default, COD as exception x86/cpu: Comment Skylake server stepping too x86/cpu: Resort and comment Intel models objtool/x86: Rewrite retpoline thunk calls objtool: Skip magical retpoline .altinstr_replacement objtool: Cache instruction relocs objtool: Keep track of retpoline call sites objtool: Add elf_create_undef_symbol() objtool: Extract elf_symbol_add() objtool: Extract elf_strtab_concat() objtool: Create reloc sections implicitly objtool: Add elf_create_reloc() helper objtool: Rework the elf_rebuild_reloc_section() logic objtool: Fix static_call list generation objtool: Handle per arch retpoline naming objtool: Correctly handle retpoline thunk calls x86/retpoline: Simplify retpolines x86/alternatives: Optimize optimize_nops() x86: Add insn_decode_kernel() x86/kprobes: Move 'inline' to the beginning of the kprobe_is_ss() declaration ...
2021-04-26Merge tag 'x86_build_for_v5.13' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 build updates from Borislav Petkov: "A bunch of clang build fixes and a Kconfig highmem selection fix for 486SX" * tag 'x86_build_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/build: Disable HIGHMEM64G selection for M486SX efi/libstub: Add $(CLANG_FLAGS) to x86 flags x86/boot: Add $(CLANG_FLAGS) to compressed KBUILD_CFLAGS x86/build: Propagate $(CLANG_FLAGS) to $(REALMODE_FLAGS)
2021-04-26Merge tag 'x86_cleanups_for_v5.13' of ↵Linus Torvalds3-4/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull misc x86 cleanups from Borislav Petkov: "Trivial cleanups and fixes all over the place" * tag 'x86_cleanups_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: MAINTAINERS: Remove me from IDE/ATAPI section x86/pat: Do not compile stubbed functions when X86_PAT is off x86/asm: Ensure asm/proto.h can be included stand-alone x86/platform/intel/quark: Fix incorrect kernel-doc comment syntax in files x86/msr: Make locally used functions static x86/cacheinfo: Remove unneeded dead-store initialization x86/process/64: Move cpu_current_top_of_stack out of TSS tools/turbostat: Unmark non-kernel-doc comment x86/syscalls: Fix -Wmissing-prototypes warnings from COND_SYSCALL() x86/fpu/math-emu: Fix function cast warning x86/msr: Fix wr/rdmsr_safe_regs_on_cpu() prototypes x86: Fix various typos in comments, take #2 x86: Remove unusual Unicode characters from comments x86/kaslr: Return boolean values from a function returning bool x86: Fix various typos in comments x86/setup: Remove unused RESERVE_BRK_ARRAY() stacktrace: Move documentation for arch_stack_walk_reliable() to header x86: Remove duplicate TSC DEADLINE MSR definitions
2021-04-26Merge tag 'x86_boot_for_v5.13' of ↵Linus Torvalds1-2/+0
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 boot updates from Borislav Petkov: "Consolidation and cleanup of the early memory reservations, along with a couple of gcc11 warning fixes" * tag 'x86_boot_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/setup: Move trim_snb_memory() later in setup_arch() to fix boot hangs x86/setup: Merge several reservations of start of memory x86/setup: Consolidate early memory reservations x86/boot/compressed: Avoid gcc-11 -Wstringop-overread warning x86/boot/tboot: Avoid Wstringop-overread-warning
2021-03-26x86/boot: Add $(CLANG_FLAGS) to compressed KBUILD_CFLAGSNathan Chancellor1-0/+1
When cross compiling x86 on an ARM machine with clang, there are several errors along the lines of: arch/x86/include/asm/string_64.h:27:10: error: invalid output constraint '=&c' in asm This happens because the compressed boot Makefile reassigns KBUILD_CFLAGS and drops the clang flags that set the target architecture ('--target=') and the path to the GNU cross tools ('--prefix='), meaning that the host architecture is targeted. These flags are available as $(CLANG_FLAGS) from the main Makefile so add them to the compressed boot folder's KBUILD_CFLAGS so that cross compiling works as expected. Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Acked-by: Ard Biesheuvel <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-03-23x86/boot/compressed: Avoid gcc-11 -Wstringop-overread warningArnd Bergmann1-2/+0
GCC gets confused by the comparison of a pointer to an integer literal, with the assumption that this is an offset from a NULL pointer and that dereferencing it is invalid: In file included from arch/x86/boot/compressed/misc.c:18: In function ‘parse_elf’, inlined from ‘extract_kernel’ at arch/x86/boot/compressed/misc.c:442:2: arch/x86/boot/compressed/../string.h:15:23: error: ‘__builtin_memcpy’ reading 64 bytes from a region of size 0 [-Werror=stringop-overread] 15 | #define memcpy(d,s,l) __builtin_memcpy(d,s,l) | ^~~~~~~~~~~~~~~~~~~~~~~ arch/x86/boot/compressed/misc.c:283:9: note: in expansion of macro ‘memcpy’ 283 | memcpy(&ehdr, output, sizeof(ehdr)); | ^~~~~~ I could not find any good workaround for this, but as this is only a warning for a failure during early boot, removing the line entirely works around the warning. Signed-off-by: Arnd Bergmann <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Martin Sebor <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2021-03-21x86: Fix various typos in comments, take #2Ingo Molnar2-2/+2
Fix another ~42 single-word typos in arch/x86/ code comments, missed a few in the first pass, in particular in .S files. Signed-off-by: Ingo Molnar <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Bjorn Helgaas <[email protected]> Cc: [email protected]
2021-03-19x86/kaslr: Return boolean values from a function returning boolJiapeng Chong1-2/+2
Fix the following coccicheck warnings: ./arch/x86/boot/compressed/kaslr.c:642:10-11: WARNING: return of 0/1 in function 'process_mem_region' with return type bool. Reported-by: Abaci Robot <[email protected]> Signed-off-by: Jiapeng Chong <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/1615283963-67277-1-git-send-email-jiapeng.chong@linux.alibaba.com
2021-03-18x86/sev-es: Replace open-coded hlt-loops with sev_es_terminate()Joerg Roedel1-9/+3
There are a few places left in the SEV-ES C code where hlt loops and/or terminate requests are implemented. Replace them all with calls to sev_es_terminate(). Signed-off-by: Joerg Roedel <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-03-18x86/boot/compressed/64: Check SEV encryption in the 32-bit boot-pathJoerg Roedel1-0/+83
Check whether the hypervisor reported the correct C-bit when running as an SEV guest. Using a wrong C-bit position could be used to leak sensitive data from the guest to the hypervisor. Signed-off-by: Joerg Roedel <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-03-18x86/boot/compressed/64: Add CPUID sanity check to 32-bit boot-pathJoerg Roedel1-0/+28
The 32-bit #VC handler has no GHCB and can only handle CPUID exit codes. It is needed by the early boot code to handle #VC exceptions raised in verify_cpu() and to get the position of the C-bit. But the CPUID information comes from the hypervisor which is untrusted and might return results which trick the guest into the no-SEV boot path with no C-bit set in the page-tables. All data written to memory would then be unencrypted and could leak sensitive data to the hypervisor. Add sanity checks to the 32-bit boot #VC handler to make sure the hypervisor does not pretend that SEV is not enabled. Signed-off-by: Joerg Roedel <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-03-18x86/boot/compressed/64: Add 32-bit boot #VC handlerJoerg Roedel2-1/+101
Add a #VC exception handler which is used when the kernel still executes in protected mode. This boot-path already uses CPUID, which will cause #VC exceptions in an SEV-ES guest. Signed-off-by: Joerg Roedel <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-03-18x86/boot/compressed/64: Setup IDT in startup_32 boot pathJoerg Roedel1-0/+72
This boot path needs exception handling when it is used with SEV-ES. Setup an IDT and provide a helper function to write IDT entries for use in 32-bit protected mode. Signed-off-by: Joerg Roedel <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-03-18x86/boot/compressed/64: Reload CS in startup_32Joerg Roedel1-1/+8
Exception handling in the startup_32 boot path requires the CS selector to be correctly set up. Reload it from the current GDT. Signed-off-by: Joerg Roedel <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-03-18x86/sev: Do not require Hypervisor CPUID bit for SEV guestsJoerg Roedel1-6/+0
A malicious hypervisor could disable the CPUID intercept for an SEV or SEV-ES guest and trick it into the no-SEV boot path, where it could potentially reveal secrets. This is not an issue for SEV-SNP guests, as the CPUID intercept can't be disabled for those. Remove the Hypervisor CPUID bit check from the SEV detection code to protect against this kind of attack and add a Hypervisor bit equals zero check to the SME detection path to prevent non-encrypted guests from trying to enable SME. This handles the following cases: 1) SEV(-ES) guest where CPUID intercept is disabled. The guest will still see leaf 0x8000001f and the SEV bit. It can retrieve the C-bit and boot normally. 2) Non-encrypted guests with intercepted CPUID will check the SEV_STATUS MSR and find it 0 and will try to enable SME. This will fail when the guest finds MSR_K8_SYSCFG to be zero, as it is emulated by KVM. But we can't rely on that, as there might be other hypervisors which return this MSR with bit 23 set. The Hypervisor bit check will prevent that the guest tries to enable SME in this case. 3) Non-encrypted guests on SEV capable hosts with CPUID intercept disabled (by a malicious hypervisor) will try to boot into the SME path. This will fail, but it is also not considered a problem because non-encrypted guests have no protection against the hypervisor anyway. [ bp: s/non-SEV/non-encrypted/g ] Signed-off-by: Joerg Roedel <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Acked-by: Tom Lendacky <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-03-18x86/boot/compressed/64: Cleanup exception handling before booting kernelJoerg Roedel3-5/+22
Disable the exception handling before booting the kernel to make sure any exceptions that happen during early kernel boot are not directed to the pre-decompression code. Signed-off-by: Joerg Roedel <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2021-03-15x86/boot/compressed/sev-es: Convert to insn_decode()Borislav Petkov1-6/+5
Other than simplifying the code there should be no functional changes resulting from this. Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-12-24Merge tag 'efi_updates_for_v5.11' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull EFI updates from Borislav Petkov: "These got delayed due to a last minute ia64 build issue which got fixed in the meantime. EFI updates collected by Ard Biesheuvel: - Don't move BSS section around pointlessly in the x86 decompressor - Refactor helper for discovering the EFI secure boot mode - Wire up EFI secure boot to IMA for arm64 - Some fixes for the capsule loader - Expose the RT_PROP table via the EFI test module - Relax DT and kernel placement restrictions on ARM with a few followup fixes: - fix the build breakage on IA64 caused by recent capsule loader changes - suppress a type mismatch build warning in the expansion of EFI_PHYS_ALIGN on ARM" * tag 'efi_updates_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: efi: arm: force use of unsigned type for EFI_PHYS_ALIGN efi: ia64: disable the capsule loader efi: stub: get rid of efi_get_max_fdt_addr() efi/efi_test: read RuntimeServicesSupported efi: arm: reduce minimum alignment of uncompressed kernel efi: capsule: clean scatter-gather entries from the D-cache efi: capsule: use atomic kmap for transient sglist mappings efi: x86/xen: switch to efi_get_secureboot_mode helper arm64/ima: add ima_arch support ima: generalize x86/EFI arch glue for other EFI architectures efi: generalize efi_get_secureboot efi/libstub: EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER should not default to yes efi/x86: Only copy the compressed kernel image in efi_relocate_kernel() efi/libstub/x86: simplify efi_is_native()
2020-12-22kasan, x86, s390: update undef CONFIG_KASANAndrey Konovalov1-0/+1
With the intoduction of hardware tag-based KASAN some kernel checks of this kind: ifdef CONFIG_KASAN will be updated to: if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) x86 and s390 use a trick to #undef CONFIG_KASAN for some of the code that isn't linked with KASAN runtime and shouldn't have any KASAN annotations. Also #undef CONFIG_KASAN_GENERIC with CONFIG_KASAN. Link: https://lkml.kernel.org/r/9d84bfaaf8fabe0fc89f913c9e420a30bd31a260.1606161801.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <[email protected]> Signed-off-by: Vincenzo Frascino <[email protected]> Reviewed-by: Marco Elver <[email protected]> Acked-by: Vasily Gorbik <[email protected]> Reviewed-by: Alexander Potapenko <[email protected]> Tested-by: Vincenzo Frascino <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Branislav Rankov <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Evgenii Stepanov <[email protected]> Cc: Kevin Brodsky <[email protected]> Cc: Will Deacon <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2020-12-14Merge tag 'x86_cleanups_for_v5.11' of ↵Linus Torvalds2-14/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cleanups from Borislav Petkov: "Another branch with a nicely negative diffstat, just the way I like 'em: - Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in the end (Gabriel Krisman Bertazi) - All kinds of minor cleanups all over the tree" * tag 'x86_cleanups_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) x86/ia32_signal: Propagate __user annotation properly x86/alternative: Update text_poke_bp() kernel-doc comment x86/PCI: Make a kernel-doc comment a normal one x86/asm: Drop unused RDPID macro x86/boot/compressed/64: Use TEST %reg,%reg instead of CMP $0,%reg x86/head64: Remove duplicate include x86/mm: Declare 'start' variable where it is used x86/head/64: Remove unused GET_CR2_INTO() macro x86/boot: Remove unused finalize_identity_maps() x86/uaccess: Document copy_from_user_nmi() x86/dumpstack: Make show_trace_log_lvl() static x86/mtrr: Fix a kernel-doc markup x86/setup: Remove unused MCA variables x86, libnvdimm/test: Remove COPY_MC_TEST x86: Reclaim TIF_IA32 and TIF_X32 x86/mm: Convert mmu context ia32_compat into a proper flags field x86/elf: Use e_machine to check for x32/ia32 in setup_additional_pages() elf: Expose ELF header on arch_setup_additional_pages() x86/elf: Use e_machine to select start_thread for x32 elf: Expose ELF header in compat_start_thread() ...
2020-12-06Merge tag 'x86-urgent-2020-12-06' of ↵Linus Torvalds1-3/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Thomas Gleixner: "A set of fixes for x86: - Make the AMD L3 QoS code and data priorization enable/disable mechanism work correctly. The control bit was only set/cleared on one of the CPUs in a L3 domain, but it has to be modified on all CPUs in the domain. The initial documentation was not clear about this, but the updated one from Oct 2020 spells it out. - Fix an off by one in the UV platform detection code which causes the UV hubs to be identified wrongly. The chip revisions start at 1 not at 0. - Fix a long standing bug in the evaluation of prefixes in the uprobes code which fails to handle repeated prefixes properly. The aggregate size of the prefixes can be larger than the bytes array but the code blindly iterated over the aggregate size beyond the array boundary. Add a macro to handle this case properly and use it at the affected places" * tag 'x86-urgent-2020-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/sev-es: Use new for_each_insn_prefix() macro to loop over prefixes bytes x86/insn-eval: Use new for_each_insn_prefix() macro to loop over prefixes bytes x86/uprobes: Do not use prefixes.nbytes when looping over prefixes.bytes x86/platform/uv: Fix UV4 hub revision adjustment x86/resctrl: Fix AMD L3 QOS CDP enable/disable
2020-12-06x86/sev-es: Use new for_each_insn_prefix() macro to loop over prefixes bytesMasami Hiramatsu1-3/+2
Since insn.prefixes.nbytes can be bigger than the size of insn.prefixes.bytes[] when a prefix is repeated, the proper check must be: insn.prefixes.bytes[i] != 0 and i < 4 instead of using insn.prefixes.nbytes. Use the new for_each_insn_prefix() macro which does it correctly. Debugged by Kees Cook <[email protected]>. [ bp: Massage commit message. ] Fixes: 25189d08e516 ("x86/sev-es: Add support for handling IOIO exceptions") Reported-by: [email protected] Signed-off-by: Masami Hiramatsu <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/160697106089.3146288.2052422845039649176.stgit@devnote2
2020-12-01kbuild: Hoist '--orphan-handling' into KconfigNathan Chancellor1-1/+3
Currently, '--orphan-handling=warn' is spread out across four different architectures in their respective Makefiles, which makes it a little unruly to deal with in case it needs to be disabled for a specific linker version (in this case, ld.lld 10.0.1). To make it easier to control this, hoist this warning into Kconfig and the main Makefile so that disabling it is simpler, as the warning will only be enabled in a couple places (main Makefile and a couple of compressed boot folders that blow away LDFLAGS_vmlinx) and making it conditional is easier due to Kconfig syntax. One small additional benefit of this is saving a call to ld-option on incremental builds because we will have already evaluated it for CONFIG_LD_ORPHAN_WARN. To keep the list of supported architectures the same, introduce CONFIG_ARCH_WANT_LD_ORPHAN_WARN, which an architecture can select to gain this automatically after all of the sections are specified and size asserted. A special thanks to Kees Cook for the help text on this config. Link: https://github.com/ClangBuiltLinux/linux/issues/1187 Acked-by: Kees Cook <[email protected]> Acked-by: Michael Ellerman <[email protected]> (powerpc) Reviewed-by: Nick Desaulniers <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]>