diff options
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 6 | ||||
| -rw-r--r-- | arch/powerpc/kernel/security.c | 57 | ||||
| -rw-r--r-- | arch/powerpc/kernel/time.c | 6 | ||||
| -rw-r--r-- | arch/powerpc/kernel/vmlinux.lds.S | 37 |
4 files changed, 69 insertions, 37 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 6467bdab8d40..3fd3ef352e3f 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -537,6 +537,7 @@ flush_count_cache: /* Save LR into r9 */ mflr r9 + // Flush the link stack .rept 64 bl .+4 .endr @@ -546,6 +547,11 @@ flush_count_cache: .balign 32 /* Restore LR */ 1: mtlr r9 + + // If we're just flushing the link stack, return here +3: nop + patch_site 3b patch__flush_link_stack_return + li r9,0x7fff mtctr r9 diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c index 7cfcb294b11c..bd91dceb7010 100644 --- a/arch/powerpc/kernel/security.c +++ b/arch/powerpc/kernel/security.c @@ -24,6 +24,7 @@ enum count_cache_flush_type { COUNT_CACHE_FLUSH_HW = 0x4, }; static enum count_cache_flush_type count_cache_flush_type = COUNT_CACHE_FLUSH_NONE; +static bool link_stack_flush_enabled; bool barrier_nospec_enabled; static bool no_nospec; @@ -212,11 +213,19 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c if (ccd) seq_buf_printf(&s, "Indirect branch cache disabled"); + + if (link_stack_flush_enabled) + seq_buf_printf(&s, ", Software link stack flush"); + } else if (count_cache_flush_type != COUNT_CACHE_FLUSH_NONE) { seq_buf_printf(&s, "Mitigation: Software count cache flush"); if (count_cache_flush_type == COUNT_CACHE_FLUSH_HW) seq_buf_printf(&s, " (hardware accelerated)"); + + if (link_stack_flush_enabled) + seq_buf_printf(&s, ", Software link stack flush"); + } else if (btb_flush_enabled) { seq_buf_printf(&s, "Mitigation: Branch predictor state flush"); } else { @@ -377,18 +386,49 @@ static __init int stf_barrier_debugfs_init(void) device_initcall(stf_barrier_debugfs_init); #endif /* CONFIG_DEBUG_FS */ +static void no_count_cache_flush(void) +{ + count_cache_flush_type = COUNT_CACHE_FLUSH_NONE; + pr_info("count-cache-flush: software flush disabled.\n"); +} + static void toggle_count_cache_flush(bool enable) { - if (!enable || !security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) { + if (!security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE) && + !security_ftr_enabled(SEC_FTR_FLUSH_LINK_STACK)) + enable = false; + + if (!enable) { patch_instruction_site(&patch__call_flush_count_cache, PPC_INST_NOP); - count_cache_flush_type = COUNT_CACHE_FLUSH_NONE; - pr_info("count-cache-flush: software flush disabled.\n"); +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE + patch_instruction_site(&patch__call_kvm_flush_link_stack, PPC_INST_NOP); +#endif + pr_info("link-stack-flush: software flush disabled.\n"); + link_stack_flush_enabled = false; + no_count_cache_flush(); return; } + // This enables the branch from _switch to flush_count_cache patch_branch_site(&patch__call_flush_count_cache, (u64)&flush_count_cache, BRANCH_SET_LINK); +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE + // This enables the branch from guest_exit_cont to kvm_flush_link_stack + patch_branch_site(&patch__call_kvm_flush_link_stack, + (u64)&kvm_flush_link_stack, BRANCH_SET_LINK); +#endif + + pr_info("link-stack-flush: software flush enabled.\n"); + link_stack_flush_enabled = true; + + // If we just need to flush the link stack, patch an early return + if (!security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) { + patch_instruction_site(&patch__flush_link_stack_return, PPC_INST_BLR); + no_count_cache_flush(); + return; + } + if (!security_ftr_enabled(SEC_FTR_BCCTR_FLUSH_ASSIST)) { count_cache_flush_type = COUNT_CACHE_FLUSH_SW; pr_info("count-cache-flush: full software flush sequence enabled.\n"); @@ -407,11 +447,20 @@ void setup_count_cache_flush(void) if (no_spectrev2 || cpu_mitigations_off()) { if (security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED) || security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED)) - pr_warn("Spectre v2 mitigations not under software control, can't disable\n"); + pr_warn("Spectre v2 mitigations not fully under software control, can't disable\n"); enable = false; } + /* + * There's no firmware feature flag/hypervisor bit to tell us we need to + * flush the link stack on context switch. So we set it here if we see + * either of the Spectre v2 mitigations that aim to protect userspace. + */ + if (security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED) || + security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) + security_ftr_set(SEC_FTR_FLUSH_LINK_STACK); + toggle_count_cache_flush(enable); } diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 694522308cd5..84827da01d45 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -338,7 +338,7 @@ static unsigned long vtime_delta(struct task_struct *tsk, return stime; } -void vtime_account_system(struct task_struct *tsk) +void vtime_account_kernel(struct task_struct *tsk) { unsigned long stime, stime_scaled, steal_time; struct cpu_accounting_data *acct = get_accounting(tsk); @@ -366,7 +366,7 @@ void vtime_account_system(struct task_struct *tsk) #endif } } -EXPORT_SYMBOL_GPL(vtime_account_system); +EXPORT_SYMBOL_GPL(vtime_account_kernel); void vtime_account_idle(struct task_struct *tsk) { @@ -395,7 +395,7 @@ static void vtime_flush_scaled(struct task_struct *tsk, /* * Account the whole cputime accumulated in the paca * Must be called with interrupts disabled. - * Assumes that vtime_account_system/idle() has been called + * Assumes that vtime_account_kernel/idle() has been called * recently (i.e. since the last entry from usermode) so that * get_paca()->user_time_scaled is up to date. */ diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 060a1acd7c6d..8834220036a5 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -6,6 +6,8 @@ #endif #define BSS_FIRST_SECTIONS *(.bss.prominit) +#define EMITS_PT_NOTE +#define RO_EXCEPTION_TABLE_ALIGN 0 #include <asm/page.h> #include <asm-generic/vmlinux.lds.h> @@ -18,22 +20,8 @@ ENTRY(_stext) PHDRS { - kernel PT_LOAD FLAGS(7); /* RWX */ - notes PT_NOTE FLAGS(0); - dummy PT_NOTE FLAGS(0); - - /* binutils < 2.18 has a bug that makes it misbehave when taking an - ELF file with all segments at load address 0 as input. This - happens when running "strip" on vmlinux, because of the AT() magic - in this linker script. People using GCC >= 4.2 won't run into - this problem, because the "build-id" support will put some data - into the "notes" segment (at a non-zero load address). - - To work around this, we force some data into both the "dummy" - segment and the kernel segment, so the dummy segment will get a - non-zero load address. It's not enough to always create the - "notes" segment, since if nothing gets assigned to it, its load - address will be zero. */ + text PT_LOAD FLAGS(7); /* RWX */ + note PT_NOTE FLAGS(0); } #ifdef CONFIG_PPC64 @@ -77,7 +65,7 @@ SECTIONS #else /* !CONFIG_PPC64 */ HEAD_TEXT #endif - } :kernel + } :text __head_end = .; @@ -126,7 +114,7 @@ SECTIONS __got2_end = .; #endif /* CONFIG_PPC32 */ - } :kernel + } :text . = ALIGN(ETEXT_ALIGN_SIZE); _etext = .; @@ -175,17 +163,6 @@ SECTIONS __stop__btb_flush_fixup = .; } #endif - EXCEPTION_TABLE(0) - - NOTES :kernel :notes - - /* The dummy segment contents for the bug workaround mentioned above - near PHDRS. */ - .dummy : AT(ADDR(.dummy) - LOAD_OFFSET) { - LONG(0) - LONG(0) - LONG(0) - } :kernel :dummy /* * Init sections discarded at runtime @@ -200,7 +177,7 @@ SECTIONS #ifdef CONFIG_PPC64 *(.tramp.ftrace.init); #endif - } :kernel + } :text /* .exit.text is discarded at runtime, not link time, * to deal with references from __bug_table |