Merge tag 'random-6.12-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:
 "Originally I'd planned on sending each of the vDSO getrandom()
  architecture ports to their respective arch trees. But as we started
  to work on this, we found lots of interesting issues in the shared
  code and infrastructure, the fixes for which the various archs needed
  to base their work.

  So in the end, this turned into a nice collaborative effort fixing up
  issues and porting to 5 new architectures -- arm64, powerpc64,
  powerpc32, s390x, and loongarch64 -- with everybody pitching in and
  commenting on each other's code. It was a fun development cycle.

  This contains:

   - Numerous fixups to the vDSO selftest infrastructure, getting it
     running successfully on more platforms, and fixing bugs in it.

   - Additions to the vDSO getrandom & chacha selftests. Basically every
     time manual review unearthed a bug in a revision of an arch patch,
     or an ambiguity, the tests were augmented.

     By the time the last arch was submitted for review, s390x, v1 of
     the series was essentially fine right out of the gate.

   - Fixes to the the generic C implementation of vDSO getrandom, to
     build and run successfully on all archs, decoupling it from
     assumptions we had (unintentionally) made on x86_64 that didn't
     carry through to the other architectures.

   - Port of vDSO getrandom to LoongArch64, from Xi Ruoyao and acked by
     Huacai Chen.

   - Port of vDSO getrandom to ARM64, from Adhemerval Zanella and acked
     by Will Deacon.

   - Port of vDSO getrandom to PowerPC, in both 32-bit and 64-bit
     varieties, from Christophe Leroy and acked by Michael Ellerman.

   - Port of vDSO getrandom to S390X from Heiko Carstens, the arch
     maintainer.

  While it'd be natural for there to be things to fix up over the course
  of the development cycle, these patches got a decent amount of review
  from a fairly diverse crew of folks on the mailing lists, and, for the
  most part, they've been cooking in linux-next, which has been helpful
  for ironing out build issues.

  In terms of architectures, I think that mostly takes care of the
  important 64-bit archs with hardware still being produced and running
  production loads in settings where vDSO getrandom is likely to help.

  Arguably there's still RISC-V left, and we'll see for 6.13 whether
  they find it useful and submit a port"

* tag 'random-6.12-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (47 commits)
  selftests: vDSO: check cpu caps before running chacha test
  s390/vdso: Wire up getrandom() vdso implementation
  s390/vdso: Move vdso symbol handling to separate header file
  s390/vdso: Allow alternatives in vdso code
  s390/module: Provide find_section() helper
  s390/facility: Let test_facility() generate static branch if possible
  s390/alternatives: Remove ALT_FACILITY_EARLY
  s390/facility: Disable compile time optimization for decompressor code
  selftests: vDSO: fix vdso_config for s390
  selftests: vDSO: fix ELF hash table entry size for s390x
  powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO64
  powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32
  powerpc/vdso: Refactor CFLAGS for CVDSO build
  powerpc/vdso32: Add crtsavres
  mm: Define VM_DROPPABLE for powerpc/32
  powerpc/vdso: Fix VDSO data access when running in a non-root time namespace
  selftests: vDSO: don't include generated headers for chacha test
  arm64: vDSO: Wire up getrandom() vDSO implementation
  arm64: alternative: make alternative_has_cap_likely() VDSO compatible
  selftests: vDSO: also test counter in vdso_test_chacha
  ...

4 files changed, 78 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/mman.h b/arch/powerpc/include/asm/mman.h
index 17a77d47ed6d..42a51a993d94 100644
--- a/arch/powerpc/include/asm/mman.h
+++ b/arch/powerpc/include/asm/mman.h
@@ -6,7 +6,7 @@
 
 #include <uapi/asm/mman.h>
 
-#ifdef CONFIG_PPC64
+#if defined(CONFIG_PPC64) && !defined(BUILD_VDSO)
 
 #include <asm/cputable.h>
 #include <linux/mm.h>
diff --git a/arch/powerpc/include/asm/vdso/getrandom.h b/arch/powerpc/include/asm/vdso/getrandom.h
new file mode 100644
index 000000000000..501d6bb14e8a
--- /dev/null
+++ b/arch/powerpc/include/asm/vdso/getrandom.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy@csgroup.eu>, CS GROUP France
+ */
+#ifndef _ASM_POWERPC_VDSO_GETRANDOM_H
+#define _ASM_POWERPC_VDSO_GETRANDOM_H
+
+#ifndef __ASSEMBLY__
+
+static __always_inline int do_syscall_3(const unsigned long _r0, const unsigned long _r3,
+					const unsigned long _r4, const unsigned long _r5)
+{
+	register long r0 asm("r0") = _r0;
+	register unsigned long r3 asm("r3") = _r3;
+	register unsigned long r4 asm("r4") = _r4;
+	register unsigned long r5 asm("r5") = _r5;
+	register int ret asm ("r3");
+
+	asm volatile(
+		"       sc\n"
+		"	bns+	1f\n"
+		"	neg	%0, %0\n"
+		"1:\n"
+	: "=r" (ret), "+r" (r4), "+r" (r5), "+r" (r0)
+	: "r" (r3)
+	: "memory", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "cr0", "ctr");
+
+	return ret;
+}
+
+/**
+ * getrandom_syscall - Invoke the getrandom() syscall.
+ * @buffer:	Destination buffer to fill with random bytes.
+ * @len:	Size of @buffer in bytes.
+ * @flags:	Zero or more GRND_* flags.
+ * Returns:	The number of bytes written to @buffer, or a negative value indicating an error.
+ */
+static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags)
+{
+	return do_syscall_3(__NR_getrandom, (unsigned long)buffer,
+			    (unsigned long)len, (unsigned long)flags);
+}
+
+static __always_inline struct vdso_rng_data *__arch_get_vdso_rng_data(void)
+{
+	return NULL;
+}
+
+ssize_t __c_kernel_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state,
+			     size_t opaque_len, const struct vdso_rng_data *vd);
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* _ASM_POWERPC_VDSO_GETRANDOM_H */
diff --git a/arch/powerpc/include/asm/vdso/vsyscall.h b/arch/powerpc/include/asm/vdso/vsyscall.h
index 48cf23f1e273..92f480d8cc6d 100644
--- a/arch/powerpc/include/asm/vdso/vsyscall.h
+++ b/arch/powerpc/include/asm/vdso/vsyscall.h
@@ -17,6 +17,12 @@ struct vdso_data *__arch_get_k_vdso_data(void)
 }
 #define __arch_get_k_vdso_data __arch_get_k_vdso_data
 
+static __always_inline
+struct vdso_rng_data *__arch_get_k_vdso_rng_data(void)
+{
+	return &vdso_data->rng_data;
+}
+
 /* The asm-generic header needs to be included after the definitions above */
 #include <asm-generic/vdso/vsyscall.h>
 
diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index a585c8e538ff..248dee138f7b 100644
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -83,6 +83,7 @@ struct vdso_arch_data {
 	__u32 compat_syscall_map[SYSCALL_MAP_SIZE];	/* Map of compat syscalls */
 
 	struct vdso_data data[CS_BASES];
+	struct vdso_rng_data rng_data;
 };
 
 #else /* CONFIG_PPC64 */
@@ -95,6 +96,7 @@ struct vdso_arch_data {
 	__u32 syscall_map[SYSCALL_MAP_SIZE]; /* Map of syscalls */
 	__u32 compat_syscall_map[0];	/* No compat syscalls on PPC32 */
 	struct vdso_data data[CS_BASES];
+	struct vdso_rng_data rng_data;
 };
 
 #endif /* CONFIG_PPC64 */
@@ -111,6 +113,21 @@ extern struct vdso_arch_data *vdso_data;
 	addi	\ptr, \ptr, (_vdso_datapage - 999b)@l
 .endm
 
+#include <asm/asm-offsets.h>
+#include <asm/page.h>
+
+.macro get_realdatapage ptr scratch
+	get_datapage \ptr
+#ifdef CONFIG_TIME_NS
+	lwz	\scratch, VDSO_CLOCKMODE_OFFSET(\ptr)
+	xoris	\scratch, \scratch, VDSO_CLOCKMODE_TIMENS@h
+	xori	\scratch, \scratch, VDSO_CLOCKMODE_TIMENS@l
+	cntlzw	\scratch, \scratch
+	rlwinm	\scratch, \scratch, PAGE_SHIFT - 5, 1 << PAGE_SHIFT
+	add	\ptr, \ptr, \scratch
+#endif
+.endm
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __KERNEL__ */