[PATCH v5 0/5] Wire up getrandom() vDSO implementation on powerpc

[PATCH v5 0/5] Wire up getrandom() vDSO implementation on powerpc

[Christophe Leroy]

This series wires up getrandom() vDSO implementation on powerpc.

Tested on PPC32 on real hardware.
Tested on PPC64 (both BE and LE) on QEMU:

Performance on powerpc 885:
	~# ./vdso_test_getrandom bench-single
	   vdso: 25000000 times in 62.938002291 seconds
	   libc: 25000000 times in 535.581916866 seconds
	syscall: 25000000 times in 531.525042806 seconds

Performance on powerpc 8321:
	~# ./vdso_test_getrandom bench-single
	   vdso: 25000000 times in 16.899318858 seconds
	   libc: 25000000 times in 131.050596522 seconds
	syscall: 25000000 times in 129.794790389 seconds

Performance on QEMU pseries:
	~ # ./vdso_test_getrandom bench-single
	   vdso: 25000000 times in 4.977777162 seconds
	   libc: 25000000 times in 75.516749981 seconds
	syscall: 25000000 times in 86.842242014 seconds

Changes in v5:
- The split between last two patches is not anymore PPC32/PPC64 but VDSO32/VDSO64
- Removed the stub returning ENOSYS
- Using meaningfull names for registers
- Restored symbolic link that disappeared in v4

Changes in v4:
- Rebased on recent random git tree (963233ff0133) (The new tree includes selftests fixes)
- Read/write counter in native byte order
- Don't use anymore compat macros to write output
- Fixed selftests build failure with patch 4 (without patch 5) on little endian on PPC64
- Implement a __kernel_getrandom() stub returning ENOSYS on ppc64 in patch 4 (without patch 5) to make selftests happy.

Changes in v3:
- Rebased on recent random git tree (0c7e00e22c21)
- Fixed build failures reported by robots around VM_DROPPABLE
- Fixed crash on PPC64 due to clobbered r13 by not using r13 anymore (saving it was not enough for signals).
- Split final patch in two, first for PPC32, second for PPC64
- Moved selftest fixes out of this series

Changes in v2:
- Define VM_DROPPABLE for powerpc/32
- Fixes generic vDSO getrandom headers to enable CONFIG_COMPAT build.
- Fixed size of generation counter
- Fixed selftests to work on non x86 architectures

Christophe Leroy (5):
  mm: Define VM_DROPPABLE for powerpc/32
  powerpc/vdso32: Add crtsavres
  powerpc/vdso: Refactor CFLAGS for CVDSO build
  powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32
  powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO64

 arch/powerpc/Kconfig                         |   1 +
 arch/powerpc/include/asm/mman.h              |   2 +-
 arch/powerpc/include/asm/vdso/getrandom.h    |  54 +++
 arch/powerpc/include/asm/vdso/vsyscall.h     |   6 +
 arch/powerpc/include/asm/vdso_datapage.h     |   2 +
 arch/powerpc/kernel/asm-offsets.c            |   1 +
 arch/powerpc/kernel/vdso/Makefile            |  57 +--
 arch/powerpc/kernel/vdso/getrandom.S         |  58 +++
 arch/powerpc/kernel/vdso/gettimeofday.S      |  13 -
 arch/powerpc/kernel/vdso/vdso32.lds.S        |   1 +
 arch/powerpc/kernel/vdso/vdso64.lds.S        |   1 +
 arch/powerpc/kernel/vdso/vgetrandom-chacha.S | 365 +++++++++++++++++++
 arch/powerpc/kernel/vdso/vgetrandom.c        |  14 +
 fs/proc/task_mmu.c                           |   4 +-
 include/linux/mm.h                           |   4 +-
 include/trace/events/mmflags.h               |   4 +-
 tools/arch/powerpc/vdso                      |   1 +
 tools/testing/selftests/vDSO/Makefile        |   2 +-
 18 files changed, 547 insertions(+), 43 deletions(-)
 create mode 100644 arch/powerpc/include/asm/vdso/getrandom.h
 create mode 100644 arch/powerpc/kernel/vdso/getrandom.S
 create mode 100644 arch/powerpc/kernel/vdso/vgetrandom-chacha.S
 create mode 100644 arch/powerpc/kernel/vdso/vgetrandom.c
 create mode 120000 tools/arch/powerpc/vdso

-- 
2.44.0

[PATCH v5 1/5] mm: Define VM_DROPPABLE for powerpc/32

[Christophe Leroy]

Commit 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always
lazily freeable mappings") only adds VM_DROPPABLE for 64 bits
architectures.

In order to also use the getrandom vDSO implementation on powerpc/32,
use VM_ARCH_1 for VM_DROPPABLE on powerpc/32. This is possible because
VM_ARCH_1 is used for VM_SAO on powerpc and VM_SAO is only for
powerpc/64. It is used in combination with PROT_SAO in some parts of
code that are restricted to CONFIG_PPC64 through #ifdefs, it is
therefore possible to define VM_SAO for CONFIG_PPC64 only.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v4: Added more details in commit message following comment from Michael.
v3: Fixed build failure reported by robots.
---
 fs/proc/task_mmu.c             | 4 +++-
 include/linux/mm.h             | 4 +++-
 include/trace/events/mmflags.h | 4 ++--
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 5f171ad7b436..3a07e13e2f81 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -987,8 +987,10 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
 #ifdef CONFIG_X86_USER_SHADOW_STACK
 		[ilog2(VM_SHADOW_STACK)] = "ss",
 #endif
-#ifdef CONFIG_64BIT
+#if defined(CONFIG_64BIT) || defined(CONFIG_PPC32)
 		[ilog2(VM_DROPPABLE)] = "dp",
+#endif
+#ifdef CONFIG_64BIT
 		[ilog2(VM_SEALED)] = "sl",
 #endif
 	};
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6549d0979b28..028847f39442 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -359,7 +359,7 @@ extern unsigned int kobjsize(const void *objp);
 
 #if defined(CONFIG_X86)
 # define VM_PAT		VM_ARCH_1	/* PAT reserves whole VMA at once (x86) */
-#elif defined(CONFIG_PPC)
+#elif defined(CONFIG_PPC64)
 # define VM_SAO		VM_ARCH_1	/* Strong Access Ordering (powerpc) */
 #elif defined(CONFIG_PARISC)
 # define VM_GROWSUP	VM_ARCH_1
@@ -409,6 +409,8 @@ extern unsigned int kobjsize(const void *objp);
 #ifdef CONFIG_64BIT
 #define VM_DROPPABLE_BIT	40
 #define VM_DROPPABLE		BIT(VM_DROPPABLE_BIT)
+#elif defined(CONFIG_PPC32)
+#define VM_DROPPABLE		VM_ARCH_1
 #else
 #define VM_DROPPABLE		VM_NONE
 #endif
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index b63d211bd141..37265977d524 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -143,7 +143,7 @@ IF_HAVE_PG_ARCH_X(arch_3)
 
 #if defined(CONFIG_X86)
 #define __VM_ARCH_SPECIFIC_1 {VM_PAT,     "pat"           }
-#elif defined(CONFIG_PPC)
+#elif defined(CONFIG_PPC64)
 #define __VM_ARCH_SPECIFIC_1 {VM_SAO,     "sao"           }
 #elif defined(CONFIG_PARISC)
 #define __VM_ARCH_SPECIFIC_1 {VM_GROWSUP,	"growsup"	}
@@ -165,7 +165,7 @@ IF_HAVE_PG_ARCH_X(arch_3)
 # define IF_HAVE_UFFD_MINOR(flag, name)
 #endif
 
-#ifdef CONFIG_64BIT
+#if defined(CONFIG_64BIT) || defined(CONFIG_PPC32)
 # define IF_HAVE_VM_DROPPABLE(flag, name) {flag, name},
 #else
 # define IF_HAVE_VM_DROPPABLE(flag, name)
-- 
2.44.0

[PATCH v5 2/5] powerpc/vdso32: Add crtsavres

[Christophe Leroy]

Commit 08c18b63d965 ("powerpc/vdso32: Add missing _restgpr_31_x to fix
build failure") added _restgpr_31_x to the vdso for gettimeofday, but
the work on getrandom shows that we will need more of those functions.

Remove _restgpr_31_x and link in crtsavres.o so that we get all
save/restore functions when optimising the kernel for size.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/vdso/Makefile       |  5 ++++-
 arch/powerpc/kernel/vdso/gettimeofday.S | 13 -------------
 2 files changed, 4 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index 1425b6edc66b..c07a425b8f78 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -43,6 +43,7 @@ else
 endif
 
 targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday-32.o
+targets += crtsavres-32.o
 obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
 targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o
 obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
@@ -68,7 +69,7 @@ targets += vdso64.lds
 CPPFLAGS_vdso64.lds += -P -C
 
 # link rule for the .so file, .lds has to be first
-$(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o FORCE
+$(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o $(obj)/crtsavres-32.o FORCE
 	$(call if_changed,vdso32ld_and_check)
 $(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o FORCE
 	$(call if_changed,vdso64ld_and_check)
@@ -76,6 +77,8 @@ $(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o
 # assembly rules for the .S files
 $(obj-vdso32): %-32.o: %.S FORCE
 	$(call if_changed_dep,vdso32as)
+$(obj)/crtsavres-32.o: %-32.o: $(srctree)/arch/powerpc/lib/crtsavres.S FORCE
+	$(call if_changed_dep,vdso32as)
 $(obj)/vgettimeofday-32.o: %-32.o: %.c FORCE
 	$(call if_changed_dep,vdso32cc)
 $(obj-vdso64): %-64.o: %.S FORCE
diff --git a/arch/powerpc/kernel/vdso/gettimeofday.S b/arch/powerpc/kernel/vdso/gettimeofday.S
index 48fc6658053a..67254ac9c8bb 100644
--- a/arch/powerpc/kernel/vdso/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso/gettimeofday.S
@@ -118,16 +118,3 @@ V_FUNCTION_END(__kernel_clock_getres)
 V_FUNCTION_BEGIN(__kernel_time)
 	cvdso_call __c_kernel_time call_time=1
 V_FUNCTION_END(__kernel_time)
-
-/* Routines for restoring integer registers, called by the compiler.  */
-/* Called with r11 pointing to the stack header word of the caller of the */
-/* function, just beyond the end of the integer restore area.  */
-#ifndef __powerpc64__
-_GLOBAL(_restgpr_31_x)
-_GLOBAL(_rest32gpr_31_x)
-	lwz	r0,4(r11)
-	lwz	r31,-4(r11)
-	mtlr	r0
-	mr	r1,r11
-	blr
-#endif
-- 
2.44.0

[PATCH v5 3/5] powerpc/vdso: Refactor CFLAGS for CVDSO build

[Christophe Leroy]

In order to avoid two much duplication when we add new VDSO
functionnalities in C like getrandom, refactor common CFLAGS.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v3: Also refactor removed flags
---
 arch/powerpc/kernel/vdso/Makefile | 32 +++++++++++++------------------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index c07a425b8f78..67fe79d26fae 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -10,28 +10,11 @@ obj-vdso64 = sigtramp64-64.o gettimeofday-64.o datapage-64.o cacheflush-64.o not
 
 ifneq ($(c-gettimeofday-y),)
   CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
-  CFLAGS_vgettimeofday-32.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
-  CFLAGS_vgettimeofday-32.o += $(call cc-option, -fno-stack-protector)
-  CFLAGS_vgettimeofday-32.o += -DDISABLE_BRANCH_PROFILING
-  CFLAGS_vgettimeofday-32.o += -ffreestanding -fasynchronous-unwind-tables
-  CFLAGS_REMOVE_vgettimeofday-32.o = $(CC_FLAGS_FTRACE)
-  CFLAGS_REMOVE_vgettimeofday-32.o += -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc
-  # This flag is supported by clang for 64-bit but not 32-bit so it will cause
-  # an unused command line flag warning for this file.
-  ifdef CONFIG_CC_IS_CLANG
-  CFLAGS_REMOVE_vgettimeofday-32.o += -fno-stack-clash-protection
-  endif
-  CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y)
-  CFLAGS_vgettimeofday-64.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
-  CFLAGS_vgettimeofday-64.o += $(call cc-option, -fno-stack-protector)
-  CFLAGS_vgettimeofday-64.o += -DDISABLE_BRANCH_PROFILING
-  CFLAGS_vgettimeofday-64.o += -ffreestanding -fasynchronous-unwind-tables
-  CFLAGS_REMOVE_vgettimeofday-64.o = $(CC_FLAGS_FTRACE)
 # Go prior to 1.16.x assumes r30 is not clobbered by any VDSO code. That used to be true
 # by accident when the VDSO was hand-written asm code, but may not be now that the VDSO is
 # compiler generated. To avoid breaking Go tell GCC not to use r30. Impact on code
 # generation is minimal, it will just use r29 instead.
-  CFLAGS_vgettimeofday-64.o += $(call cc-option, -ffixed-r30)
+  CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y) $(call cc-option, -ffixed-r30)
 endif
 
 # Build rules
@@ -49,6 +32,11 @@ targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o
 obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
 
 ccflags-y := -fno-common -fno-builtin
+ccflags-y += $(DISABLE_LATENT_ENTROPY_PLUGIN)
+ccflags-y += $(call cc-option, -fno-stack-protector)
+ccflags-y += -DDISABLE_BRANCH_PROFILING
+ccflags-y += -ffreestanding -fasynchronous-unwind-tables
+ccflags-remove-y := $(CC_FLAGS_FTRACE)
 ldflags-y := -Wl,--hash-style=both -nostdlib -shared -z noexecstack $(CLANG_FLAGS)
 ldflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld)
 ldflags-$(CONFIG_LD_ORPHAN_WARN) += -Wl,--orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
@@ -57,6 +45,12 @@ ldflags-$(CONFIG_LD_ORPHAN_WARN) += -Wl,--orphan-handling=$(CONFIG_LD_ORPHAN_WAR
 ldflags-y += $(filter-out $(CC_AUTO_VAR_INIT_ZERO_ENABLER) $(CC_FLAGS_FTRACE) -Wa$(comma)%, $(KBUILD_CFLAGS))
 
 CC32FLAGS := -m32
+CC32FLAGSREMOVE := -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc
+  # This flag is supported by clang for 64-bit but not 32-bit so it will cause
+  # an unused command line flag warning for this file.
+ifdef CONFIG_CC_IS_CLANG
+CC32FLAGSREMOVE += -fno-stack-clash-protection
+endif
 LD32FLAGS := -Wl,-soname=linux-vdso32.so.1
 AS32FLAGS := -D__VDSO32__
 
@@ -105,7 +99,7 @@ quiet_cmd_vdso32ld_and_check = VDSO32L $@
 quiet_cmd_vdso32as = VDSO32A $@
       cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) $(AS32FLAGS) -c -o $@ $<
 quiet_cmd_vdso32cc = VDSO32C $@
-      cmd_vdso32cc = $(VDSOCC) $(c_flags) $(CC32FLAGS) -c -o $@ $<
+      cmd_vdso32cc = $(VDSOCC) $(filter-out $(CC32FLAGSREMOVE), $(c_flags)) $(CC32FLAGS) -c -o $@ $<
 
 quiet_cmd_vdso64ld_and_check = VDSO64L $@
       cmd_vdso64ld_and_check = $(VDSOCC) $(ldflags-y) $(LD64FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^); $(cmd_vdso_check)
-- 
2.44.0

[PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Christophe Leroy]

To be consistent with other VDSO functions, the function is called
__kernel_getrandom()

__arch_chacha20_blocks_nostack() fonction is implemented basically
with 32 bits operations. It performs 4 QUARTERROUND operations in
parallele. There are enough registers to avoid using the stack:

On input:
	r3: output bytes
	r4: 32-byte key input
	r5: 8-byte counter input/output
	r6: number of 64-byte blocks to write to output

During operation:
	stack: pointer to counter (r5) and non-volatile registers (r14-131)
	r0: counter of blocks (initialised with r6)
	r4: Value '4' after key has been read, used for indexing
	r5-r12: key
	r14-r15: block counter
	r16-r31: chacha state

At the end:
	r0, r6-r12: Zeroised
	r5, r14-r31: Restored

Performance on powerpc 885 (using kernel selftest):
	~# ./vdso_test_getrandom bench-single
	   vdso: 25000000 times in 62.938002291 seconds
	   libc: 25000000 times in 535.581916866 seconds
	syscall: 25000000 times in 531.525042806 seconds

Performance on powerpc 8321 (using kernel selftest):
	~# ./vdso_test_getrandom bench-single
	   vdso: 25000000 times in 16.899318858 seconds
	   libc: 25000000 times in 131.050596522 seconds
	syscall: 25000000 times in 129.794790389 seconds

This first patch adds support for VDSO32. As selftests cannot easily
be generated only for VDSO32, and because the following patch brings
support for VDSO64 anyway, this patch opts out all code in
__arch_chacha20_blocks_nostack() so that vdso_test_chacha will not
fail to compile and will not crash on PPC64/PPC64LE, allthough the
selftest itself will fail.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v5:
- Add back vdso symlink that vanished in v4 after a rebase back and forth with rejected patch "selftests: vDSO: Do not rely on $ARCH for vdso_test_getrandom && vdso_test_chacha"
- Set meaningfull names to registers and constants in chacha assembly
- Add 32 bits LE logic in this patch as well allthought it is only usefull for ppc64le.
- Remove the temporary ppc64 __kernel_getrandom added in v4, selftest will return KSFT_FAIL until following patch, not a big issue.
- Move the -DBUILD_VDSO logic in patch 3 to allow build VDSO32 on ppc64.

v4:
- Counter has native byte order
- Fix selftest build on ppc64le until implemented.
- On ppc64, for now implement __kernel_getrandom to return ENOSYS error
- Use stwbrx directly, not compat macro.

v3:
- Preserve r13, implies saving r5 on stack
- Split PPC64 implementation out.
---
 arch/powerpc/Kconfig                         |   1 +
 arch/powerpc/include/asm/mman.h              |   2 +-
 arch/powerpc/include/asm/vdso/getrandom.h    |  54 ++++
 arch/powerpc/include/asm/vdso/vsyscall.h     |   6 +
 arch/powerpc/include/asm/vdso_datapage.h     |   2 +
 arch/powerpc/kernel/asm-offsets.c            |   1 +
 arch/powerpc/kernel/vdso/Makefile            |  14 +-
 arch/powerpc/kernel/vdso/getrandom.S         |  50 +++
 arch/powerpc/kernel/vdso/vdso32.lds.S        |   1 +
 arch/powerpc/kernel/vdso/vgetrandom-chacha.S | 312 +++++++++++++++++++
 arch/powerpc/kernel/vdso/vgetrandom.c        |  14 +
 tools/arch/powerpc/vdso                      |   1 +
 tools/testing/selftests/vDSO/Makefile        |   2 +-
 13 files changed, 455 insertions(+), 5 deletions(-)
 create mode 100644 arch/powerpc/include/asm/vdso/getrandom.h
 create mode 100644 arch/powerpc/kernel/vdso/getrandom.S
 create mode 100644 arch/powerpc/kernel/vdso/vgetrandom-chacha.S
 create mode 100644 arch/powerpc/kernel/vdso/vgetrandom.c
 create mode 120000 tools/arch/powerpc/vdso

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d7b09b064a8a..e500a59ddecc 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -311,6 +311,7 @@ config PPC
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
 	select TRACE_IRQFLAGS_SUPPORT
+	select VDSO_GETRANDOM			if VDSO32
 	#
 	# Please keep this list sorted alphabetically.
 	#
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..e17500c5237e 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 */
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 23733282de4d..eedb2e04c785 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -335,6 +335,7 @@ int main(void)
 
 	/* datapage offsets for use by vdso */
 	OFFSET(VDSO_DATA_OFFSET, vdso_arch_data, data);
+	OFFSET(VDSO_RNG_DATA_OFFSET, vdso_arch_data, rng_data);
 	OFFSET(CFG_TB_TICKS_PER_SEC, vdso_arch_data, tb_ticks_per_sec);
 #ifdef CONFIG_PPC64
 	OFFSET(CFG_ICACHE_BLOCKSZ, vdso_arch_data, icache_block_size);
diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index 67fe79d26fae..7a4a935406d8 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -8,6 +8,8 @@ include $(srctree)/lib/vdso/Makefile
 obj-vdso32 = sigtramp32-32.o gettimeofday-32.o datapage-32.o cacheflush-32.o note-32.o getcpu-32.o
 obj-vdso64 = sigtramp64-64.o gettimeofday-64.o datapage-64.o cacheflush-64.o note-64.o getcpu-64.o
 
+obj-vdso32 += getrandom-32.o vgetrandom-chacha-32.o
+
 ifneq ($(c-gettimeofday-y),)
   CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
 # Go prior to 1.16.x assumes r30 is not clobbered by any VDSO code. That used to be true
@@ -17,6 +19,10 @@ ifneq ($(c-gettimeofday-y),)
   CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y) $(call cc-option, -ffixed-r30)
 endif
 
+ifneq ($(c-getrandom-y),)
+  CFLAGS_vgetrandom-32.o += -include $(c-getrandom-y)
+endif
+
 # Build rules
 
 ifdef CROSS32_COMPILE
@@ -25,13 +31,13 @@ else
     VDSOCC := $(CC)
 endif
 
-targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday-32.o
+targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday-32.o vgetrandom-32.o
 targets += crtsavres-32.o
 obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
 targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o
 obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
 
-ccflags-y := -fno-common -fno-builtin
+ccflags-y := -fno-common -fno-builtin -DBUILD_VDSO
 ccflags-y += $(DISABLE_LATENT_ENTROPY_PLUGIN)
 ccflags-y += $(call cc-option, -fno-stack-protector)
 ccflags-y += -DDISABLE_BRANCH_PROFILING
@@ -63,7 +69,7 @@ targets += vdso64.lds
 CPPFLAGS_vdso64.lds += -P -C
 
 # link rule for the .so file, .lds has to be first
-$(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o $(obj)/crtsavres-32.o FORCE
+$(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o $(obj)/vgetrandom-32.o $(obj)/crtsavres-32.o FORCE
 	$(call if_changed,vdso32ld_and_check)
 $(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o FORCE
 	$(call if_changed,vdso64ld_and_check)
@@ -75,6 +81,8 @@ $(obj)/crtsavres-32.o: %-32.o: $(srctree)/arch/powerpc/lib/crtsavres.S FORCE
 	$(call if_changed_dep,vdso32as)
 $(obj)/vgettimeofday-32.o: %-32.o: %.c FORCE
 	$(call if_changed_dep,vdso32cc)
+$(obj)/vgetrandom-32.o: %-32.o: %.c FORCE
+	$(call if_changed_dep,vdso32cc)
 $(obj-vdso64): %-64.o: %.S FORCE
 	$(call if_changed_dep,vdso64as)
 $(obj)/vgettimeofday-64.o: %-64.o: %.c FORCE
diff --git a/arch/powerpc/kernel/vdso/getrandom.S b/arch/powerpc/kernel/vdso/getrandom.S
new file mode 100644
index 000000000000..21773ef3fc1d
--- /dev/null
+++ b/arch/powerpc/kernel/vdso/getrandom.S
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Userland implementation of getrandom() for processes
+ * for use in the vDSO
+ *
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy@csgroup.eu>, CS GROUP France
+ */
+#include <asm/processor.h>
+#include <asm/ppc_asm.h>
+#include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
+#include <asm/asm-offsets.h>
+#include <asm/unistd.h>
+
+/*
+ * The macro sets two stack frames, one for the caller and one for the callee
+ * because there are no requirement for the caller to set a stack frame when
+ * calling VDSO so it may have omitted to set one, especially on PPC64
+ */
+
+.macro cvdso_call funct
+  .cfi_startproc
+	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
+  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
+	mflr		r0
+	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
+  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
+	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
+  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
+	get_datapage	r8
+	addi		r8, r8, VDSO_RNG_DATA_OFFSET
+	bl		CFUNC(DOTSYM(\funct))
+	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
+	cmpwi		r3, 0
+	mtlr		r0
+	addi		r1, r1, 2 * PPC_MIN_STKFRM
+  .cfi_restore lr
+  .cfi_def_cfa_offset 0
+	crclr		so
+	bgelr+
+	crset		so
+	neg		r3, r3
+	blr
+  .cfi_endproc
+.endm
+
+	.text
+V_FUNCTION_BEGIN(__kernel_getrandom)
+	cvdso_call __c_kernel_getrandom
+V_FUNCTION_END(__kernel_getrandom)
diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S b/arch/powerpc/kernel/vdso/vdso32.lds.S
index 8f57107000a2..7b41d5d256e8 100644
--- a/arch/powerpc/kernel/vdso/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
@@ -130,6 +130,7 @@ VERSION
 #if defined(CONFIG_PPC64) || !defined(CONFIG_SMP)
 		__kernel_getcpu;
 #endif
+		__kernel_getrandom;
 
 	local: *;
 	};
diff --git a/arch/powerpc/kernel/vdso/vgetrandom-chacha.S b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
new file mode 100644
index 000000000000..ac85788205cb
--- /dev/null
+++ b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
@@ -0,0 +1,312 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy@csgroup.eu>, CS GROUP France
+ */
+
+#include <linux/linkage.h>
+
+#include <asm/ppc_asm.h>
+
+#define	dst_bytes	r3
+#define	key		r4
+#define	counter		r5
+#define	nblocks		r6
+
+#define	idx_r0		r0
+#define	val4		r4
+
+#define	const0		0x61707865
+#define	const1		0x3320646e
+#define	const2		0x79622d32
+#define	const3		0x6b206574
+
+#define	key0		r5
+#define	key1		r6
+#define	key2		r7
+#define	key3		r8
+#define	key4		r9
+#define	key5		r10
+#define	key6		r11
+#define	key7		r12
+
+#define	counter0	r14
+#define	counter1	r15
+
+#define	state0		r16
+#define	state1		r17
+#define	state2		r18
+#define	state3		r19
+#define	state4		r20
+#define	state5		r21
+#define	state6		r22
+#define	state7		r23
+#define	state8		r24
+#define	state9		r25
+#define	state10		r26
+#define	state11		r27
+#define	state12		r28
+#define	state13		r29
+#define	state14		r30
+#define	state15		r31
+
+.macro quarterround4 a1 b1 c1 d1 a2 b2 c2 d2 a3 b3 c3 d3 a4 b4 c4 d4
+	add	\a1, \a1, \b1
+	add	\a2, \a2, \b2
+	add	\a3, \a3, \b3
+	add	\a4, \a4, \b4
+	xor	\d1, \d1, \a1
+	xor	\d2, \d2, \a2
+	xor	\d3, \d3, \a3
+	xor	\d4, \d4, \a4
+	rotlwi	\d1, \d1, 16
+	rotlwi	\d2, \d2, 16
+	rotlwi	\d3, \d3, 16
+	rotlwi	\d4, \d4, 16
+	add	\c1, \c1, \d1
+	add	\c2, \c2, \d2
+	add	\c3, \c3, \d3
+	add	\c4, \c4, \d4
+	xor	\b1, \b1, \c1
+	xor	\b2, \b2, \c2
+	xor	\b3, \b3, \c3
+	xor	\b4, \b4, \c4
+	rotlwi	\b1, \b1, 12
+	rotlwi	\b2, \b2, 12
+	rotlwi	\b3, \b3, 12
+	rotlwi	\b4, \b4, 12
+	add	\a1, \a1, \b1
+	add	\a2, \a2, \b2
+	add	\a3, \a3, \b3
+	add	\a4, \a4, \b4
+	xor	\d1, \d1, \a1
+	xor	\d2, \d2, \a2
+	xor	\d3, \d3, \a3
+	xor	\d4, \d4, \a4
+	rotlwi	\d1, \d1, 8
+	rotlwi	\d2, \d2, 8
+	rotlwi	\d3, \d3, 8
+	rotlwi	\d4, \d4, 8
+	add	\c1, \c1, \d1
+	add	\c2, \c2, \d2
+	add	\c3, \c3, \d3
+	add	\c4, \c4, \d4
+	xor	\b1, \b1, \c1
+	xor	\b2, \b2, \c2
+	xor	\b3, \b3, \c3
+	xor	\b4, \b4, \c4
+	rotlwi	\b1, \b1, 7
+	rotlwi	\b2, \b2, 7
+	rotlwi	\b3, \b3, 7
+	rotlwi	\b4, \b4, 7
+.endm
+
+#define QUARTERROUND4(a1,b1,c1,d1,a2,b2,c2,d2,a3,b3,c3,d3,a4,b4,c4,d4) \
+	quarterround4 state##a1 state##b1 state##c1 state##d1 \
+		      state##a2 state##b2 state##c2 state##d2 \
+		      state##a3 state##b3 state##c3 state##d3 \
+		      state##a4 state##b4 state##c4 state##d4
+
+/*
+ * Very basic 32 bits implementation of ChaCha20. Produces a given positive number
+ * of blocks of output with a nonce of 0, taking an input key and 8-byte
+ * counter. Importantly does not spill to the stack. Its arguments are:
+ *
+ *	r3: output bytes
+ *	r4: 32-byte key input
+ *	r5: 8-byte counter input/output (saved on stack)
+ *	r6: number of 64-byte blocks to write to output
+ *
+ *	r0: counter of blocks (initialised with r6)
+ *	r4: Value '4' after key has been read.
+ *	r5-r12: key
+ *	r14-r15: counter
+ *	r16-r31: state
+ */
+SYM_FUNC_START(__arch_chacha20_blocks_nostack)
+#ifdef __powerpc64__
+#else
+	stwu	r1, -96(r1)
+	stw	counter, 20(r1)
+#ifdef __BIG_ENDIAN__
+	stmw	r14, 24(r1)
+#else
+	stw	r14, 24(r1)
+	stw	r15, 28(r1)
+	stw	r16, 32(r1)
+	stw	r17, 36(r1)
+	stw	r18, 40(r1)
+	stw	r19, 44(r1)
+	stw	r20, 48(r1)
+	stw	r21, 52(r1)
+	stw	r22, 56(r1)
+	stw	r23, 60(r1)
+	stw	r24, 64(r1)
+	stw	r25, 68(r1)
+	stw	r26, 72(r1)
+	stw	r27, 76(r1)
+	stw	r28, 80(r1)
+	stw	r29, 84(r1)
+	stw	r30, 88(r1)
+	stw	r31, 92(r1)
+#endif
+
+	lwz	counter0, 0(counter)
+	lwz	counter1, 4(counter)
+	mr	idx_r0, nblocks
+	subi	dst_bytes, dst_bytes, 4
+
+	lwz	key0, 0(key)
+	lwz	key1, 4(key)
+	lwz	key2, 8(key)
+	lwz	key3, 12(key)
+	lwz	key4, 16(key)
+	lwz	key5, 20(key)
+	lwz	key6, 24(key)
+	lwz	key7, 28(key)
+
+	li	val4, 4
+.Lblock:
+	li	r31, 10
+
+	lis	state0, const0@ha
+	lis	state1, const1@ha
+	lis	state2, const2@ha
+	lis	state3, const3@ha
+	addi	state0, state0, const0@l
+	addi	state1, state1, const1@l
+	addi	state2, state2, const2@l
+	addi	state3, state3, const3@l
+
+	mtctr	r31
+
+	mr	state4, key0
+	mr	state5, key1
+	mr	state6, key2
+	mr	state7, key3
+	mr	state8, key4
+	mr	state9, key5
+	mr	state10, key6
+	mr	state11, key7
+
+	mr	state12, counter0
+	mr	state13, counter1
+
+	li	state14, 0
+	li	state15, 0
+
+.Lpermute:
+	QUARTERROUND4( 0, 4, 8,12, 1, 5, 9,13, 2, 6,10,14, 3, 7,11,15)
+	QUARTERROUND4( 0, 5,10,15, 1, 6,11,12, 2, 7, 8,13, 3, 4, 9,14)
+
+	bdnz	.Lpermute
+
+	addis	state0, state0, const0@ha
+	addis	state1, state1, const1@ha
+	addis	state2, state2, const2@ha
+	addis	state3, state3, const3@ha
+	addi	state0, state0, const0@l
+	addi	state1, state1, const1@l
+	addi	state2, state2, const2@l
+	addi	state3, state3, const3@l
+
+	add	state4, state4, key0
+	add	state5, state5, key1
+	add	state6, state6, key2
+	add	state7, state7, key3
+	add	state8, state8, key4
+	add	state9, state9, key5
+	add	state10, state10, key6
+	add	state11, state11, key7
+
+	add	state12, state12, counter0
+	add	state13, state13, counter1
+
+#ifdef __BIG_ENDIAN__
+	stwbrx	state0, val4, dst_bytes
+	addi	dst_bytes, dst_bytes, 8
+	stwbrx	state1, 0, dst_bytes
+	stwbrx	state2, val4, dst_bytes
+	addi	dst_bytes, dst_bytes, 8
+	stwbrx	state3, 0, dst_bytes
+	stwbrx	state4, val4, dst_bytes
+	addi	dst_bytes, dst_bytes, 8
+	stwbrx	state5, 0, dst_bytes
+	stwbrx	state6, val4, dst_bytes
+	addi	dst_bytes, dst_bytes, 8
+	stwbrx	state7, 0, dst_bytes
+	stwbrx	state8, val4, dst_bytes
+	addi	dst_bytes, dst_bytes, 8
+	stwbrx	state9, 0, dst_bytes
+	stwbrx	state10, val4, dst_bytes
+	addi	dst_bytes, dst_bytes, 8
+	stwbrx	state11, 0, dst_bytes
+	stwbrx	state12, val4, dst_bytes
+	addi	dst_bytes, dst_bytes, 8
+	stwbrx	state13, 0, dst_bytes
+	stwbrx	state14, val4, dst_bytes
+	addi	dst_bytes, dst_bytes, 8
+	stwbrx	state15, 0, dst_bytes
+#else
+	stw	state0, 4(dst_bytes)
+	stw	state1, 8(dst_bytes)
+	stw	state2, 12(dst_bytes)
+	stw	state3, 16(dst_bytes)
+	stw	state4, 20(dst_bytes)
+	stw	state5, 24(dst_bytes)
+	stw	state6, 28(dst_bytes)
+	stw	state7, 32(dst_bytes)
+	stw	state8, 36(dst_bytes)
+	stw	state9, 40(dst_bytes)
+	stw	state10, 44(dst_bytes)
+	stw	state11, 48(dst_bytes)
+	stw	state12, 52(dst_bytes)
+	stw	state13, 56(dst_bytes)
+	stw	state14, 60(dst_bytes)
+	stwu	state15, 64(dst_bytes)
+#endif
+
+	subic.	idx_r0, idx_r0, 1	/* subi. can't use r0 as source */
+
+	addic	counter0, counter0, 1
+	addze	counter1, counter1
+
+	bne	.Lblock
+
+	lwz	counter, 20(r1)
+	stw	counter0, 0(counter)
+	stw	counter1, 4(counter)
+
+	li	r6, 0
+	li	r7, 0
+	li	r8, 0
+	li	r9, 0
+	li	r10, 0
+	li	r11, 0
+	li	r12, 0
+
+#ifdef __BIG_ENDIAN__
+	lmw	r14, 24(r1)
+#else
+	lwz	r14, 24(r1)
+	lwz	r15, 28(r1)
+	lwz	r16, 32(r1)
+	lwz	r17, 36(r1)
+	lwz	r18, 40(r1)
+	lwz	r19, 44(r1)
+	lwz	r20, 48(r1)
+	lwz	r21, 52(r1)
+	lwz	r22, 56(r1)
+	lwz	r23, 60(r1)
+	lwz	r24, 64(r1)
+	lwz	r25, 68(r1)
+	lwz	r26, 72(r1)
+	lwz	r27, 76(r1)
+	lwz	r28, 80(r1)
+	lwz	r29, 84(r1)
+	lwz	r30, 88(r1)
+	lwz	r31, 92(r1)
+#endif
+	addi	r1, r1, 96
+#endif	/* __powerpc64__ */
+	blr
+SYM_FUNC_END(__arch_chacha20_blocks_nostack)
diff --git a/arch/powerpc/kernel/vdso/vgetrandom.c b/arch/powerpc/kernel/vdso/vgetrandom.c
new file mode 100644
index 000000000000..5f855d45fb7b
--- /dev/null
+++ b/arch/powerpc/kernel/vdso/vgetrandom.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Powerpc userspace implementation of getrandom()
+ *
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy@csgroup.eu>, CS GROUP France
+ */
+#include <linux/time.h>
+#include <linux/types.h>
+
+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)
+{
+	return __cvdso_getrandom_data(vd, buffer, len, flags, opaque_state, opaque_len);
+}
diff --git a/tools/arch/powerpc/vdso b/tools/arch/powerpc/vdso
new file mode 120000
index 000000000000..4e676d1d1cb4
--- /dev/null
+++ b/tools/arch/powerpc/vdso
@@ -0,0 +1 @@
+../../../arch/powerpc/kernel/vdso
\ No newline at end of file
diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
index 04930125035e..853e669d8643 100644
--- a/tools/testing/selftests/vDSO/Makefile
+++ b/tools/testing/selftests/vDSO/Makefile
@@ -9,7 +9,7 @@ ifeq ($(ARCH),$(filter $(ARCH),x86 x86_64))
 TEST_GEN_PROGS += vdso_standalone_test_x86
 endif
 TEST_GEN_PROGS += vdso_test_correctness
-ifeq ($(ARCH)$(CONFIG_X86_32),$(filter $(ARCH)$(CONFIG_X86_32),x86 x86_64 loongarch))
+ifeq ($(ARCH)$(CONFIG_X86_32),$(filter $(ARCH)$(CONFIG_X86_32),x86 x86_64 loongarch powerpc))
 TEST_GEN_PROGS += vdso_test_getrandom
 TEST_GEN_PROGS += vdso_test_chacha
 endif
-- 
2.44.0

[PATCH v5 5/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO64

[Christophe Leroy]

Extend getrandom() vDSO implementation to VDSO64

Tested on QEMU on both ppc64_defconfig and ppc64le_defconfig.

The results are not precise as it is QEMU on an x86 laptop, but
no need to be precise to see the benefit.

~ # ./vdso_test_getrandom bench-single
   vdso: 25000000 times in 4.977777162 seconds
   libc: 25000000 times in 75.516749981 seconds
syscall: 25000000 times in 86.842242014 seconds

~ # ./vdso_test_getrandom bench-single
   vdso: 25000000 times in 6.473814156 seconds
   libc: 25000000 times in 73.875109463 seconds
syscall: 25000000 times in 71.805066229 seconds

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v5:
- VDSO32 for both PPC32 and PPC64 is in previous patch. This patch have the logic for VDSO64.

v4:
- Use __BIG_ENDIAN__ which is defined by GCC instead of CONFIG_CPU_BIG_ENDIAN which is unknown by selftests
- Implement a cleaner/smaller output copy for little endian instead of keeping compat macro.

v3: New (split out of previous patch)
---
 arch/powerpc/Kconfig                         |  2 +-
 arch/powerpc/kernel/vdso/Makefile            |  8 ++-
 arch/powerpc/kernel/vdso/getrandom.S         |  8 +++
 arch/powerpc/kernel/vdso/vdso64.lds.S        |  1 +
 arch/powerpc/kernel/vdso/vgetrandom-chacha.S | 53 ++++++++++++++++++++
 5 files changed, 69 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e500a59ddecc..b45452ac4a73 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -311,7 +311,7 @@ config PPC
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
 	select TRACE_IRQFLAGS_SUPPORT
-	select VDSO_GETRANDOM			if VDSO32
+	select VDSO_GETRANDOM
 	#
 	# Please keep this list sorted alphabetically.
 	#
diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index 7a4a935406d8..56fb1633529a 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -9,6 +9,7 @@ obj-vdso32 = sigtramp32-32.o gettimeofday-32.o datapage-32.o cacheflush-32.o not
 obj-vdso64 = sigtramp64-64.o gettimeofday-64.o datapage-64.o cacheflush-64.o note-64.o getcpu-64.o
 
 obj-vdso32 += getrandom-32.o vgetrandom-chacha-32.o
+obj-vdso64 += getrandom-64.o vgetrandom-chacha-64.o
 
 ifneq ($(c-gettimeofday-y),)
   CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
@@ -21,6 +22,7 @@ endif
 
 ifneq ($(c-getrandom-y),)
   CFLAGS_vgetrandom-32.o += -include $(c-getrandom-y)
+  CFLAGS_vgetrandom-64.o += -include $(c-getrandom-y) $(call cc-option, -ffixed-r30)
 endif
 
 # Build rules
@@ -34,7 +36,7 @@ endif
 targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday-32.o vgetrandom-32.o
 targets += crtsavres-32.o
 obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
-targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o
+targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o vgetrandom-64.o
 obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
 
 ccflags-y := -fno-common -fno-builtin -DBUILD_VDSO
@@ -71,7 +73,7 @@ CPPFLAGS_vdso64.lds += -P -C
 # link rule for the .so file, .lds has to be first
 $(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o $(obj)/vgetrandom-32.o $(obj)/crtsavres-32.o FORCE
 	$(call if_changed,vdso32ld_and_check)
-$(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o FORCE
+$(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o $(obj)/vgetrandom-64.o FORCE
 	$(call if_changed,vdso64ld_and_check)
 
 # assembly rules for the .S files
@@ -87,6 +89,8 @@ $(obj-vdso64): %-64.o: %.S FORCE
 	$(call if_changed_dep,vdso64as)
 $(obj)/vgettimeofday-64.o: %-64.o: %.c FORCE
 	$(call if_changed_dep,cc_o_c)
+$(obj)/vgetrandom-64.o: %-64.o: %.c FORCE
+	$(call if_changed_dep,cc_o_c)
 
 # Generate VDSO offsets using helper script
 gen-vdso32sym := $(src)/gen_vdso32_offsets.sh
diff --git a/arch/powerpc/kernel/vdso/getrandom.S b/arch/powerpc/kernel/vdso/getrandom.S
index 21773ef3fc1d..a957cd2b2b03 100644
--- a/arch/powerpc/kernel/vdso/getrandom.S
+++ b/arch/powerpc/kernel/vdso/getrandom.S
@@ -27,10 +27,18 @@
   .cfi_adjust_cfa_offset PPC_MIN_STKFRM
 	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
   .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
+#ifdef __powerpc64__
+	PPC_STL		r2, PPC_MIN_STKFRM + STK_GOT(r1)
+  .cfi_rel_offset r2, PPC_MIN_STKFRM + STK_GOT
+#endif
 	get_datapage	r8
 	addi		r8, r8, VDSO_RNG_DATA_OFFSET
 	bl		CFUNC(DOTSYM(\funct))
 	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
+#ifdef __powerpc64__
+	PPC_LL		r2, PPC_MIN_STKFRM + STK_GOT(r1)
+  .cfi_restore r2
+#endif
 	cmpwi		r3, 0
 	mtlr		r0
 	addi		r1, r1, 2 * PPC_MIN_STKFRM
diff --git a/arch/powerpc/kernel/vdso/vdso64.lds.S b/arch/powerpc/kernel/vdso/vdso64.lds.S
index 400819258c06..9481e4b892ed 100644
--- a/arch/powerpc/kernel/vdso/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso64.lds.S
@@ -123,6 +123,7 @@ VERSION
 		__kernel_sigtramp_rt64;
 		__kernel_getcpu;
 		__kernel_time;
+		__kernel_getrandom;
 
 	local: *;
 	};
diff --git a/arch/powerpc/kernel/vdso/vgetrandom-chacha.S b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
index ac85788205cb..7f9061a9e8b4 100644
--- a/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
+++ b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
@@ -124,6 +124,26 @@
  */
 SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 #ifdef __powerpc64__
+	std	counter, -216(r1)
+
+	std	r14, -144(r1)
+	std	r15, -136(r1)
+	std	r16, -128(r1)
+	std	r17, -120(r1)
+	std	r18, -112(r1)
+	std	r19, -104(r1)
+	std	r20, -96(r1)
+	std	r21, -88(r1)
+	std	r22, -80(r1)
+	std	r23, -72(r1)
+	std	r24, -64(r1)
+	std	r25, -56(r1)
+	std	r26, -48(r1)
+	std	r27, -40(r1)
+	std	r28, -32(r1)
+	std	r29, -24(r1)
+	std	r30, -16(r1)
+	std	r31, -8(r1)
 #else
 	stwu	r1, -96(r1)
 	stw	counter, 20(r1)
@@ -149,9 +169,13 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 	stw	r30, 88(r1)
 	stw	r31, 92(r1)
 #endif
+#endif	/* __powerpc64__ */
 
 	lwz	counter0, 0(counter)
 	lwz	counter1, 4(counter)
+#ifdef __powerpc64__
+	rldimi	counter0, counter1, 32, 0
+#endif
 	mr	idx_r0, nblocks
 	subi	dst_bytes, dst_bytes, 4
 
@@ -267,12 +291,21 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 
 	subic.	idx_r0, idx_r0, 1	/* subi. can't use r0 as source */
 
+#ifdef __powerpc64__
+	addi	counter0, counter0, 1
+	srdi	counter1, counter0, 32
+#else
 	addic	counter0, counter0, 1
 	addze	counter1, counter1
+#endif
 
 	bne	.Lblock
 
+#ifdef __powerpc64__
+	ld	counter, -216(r1)
+#else
 	lwz	counter, 20(r1)
+#endif
 	stw	counter0, 0(counter)
 	stw	counter1, 4(counter)
 
@@ -284,6 +317,26 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 	li	r11, 0
 	li	r12, 0
 
+#ifdef __powerpc64__
+	ld	r14, -144(r1)
+	ld	r15, -136(r1)
+	ld	r16, -128(r1)
+	ld	r17, -120(r1)
+	ld	r18, -112(r1)
+	ld	r19, -104(r1)
+	ld	r20, -96(r1)
+	ld	r21, -88(r1)
+	ld	r22, -80(r1)
+	ld	r23, -72(r1)
+	ld	r24, -64(r1)
+	ld	r25, -56(r1)
+	ld	r26, -48(r1)
+	ld	r27, -40(r1)
+	ld	r28, -32(r1)
+	ld	r29, -24(r1)
+	ld	r30, -16(r1)
+	ld	r31, -8(r1)
+#else
 #ifdef __BIG_ENDIAN__
 	lmw	r14, 24(r1)
 #else
-- 
2.44.0

Re: [PATCH v5 5/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO64

[Madhavan Srinivasan]

On 9/3/24 12:47 AM, Christophe Leroy wrote:
> Extend getrandom() vDSO implementation to VDSO64
>
> Tested on QEMU on both ppc64_defconfig and ppc64le_defconfig.
>
> The results are not precise as it is QEMU on an x86 laptop, but
> no need to be precise to see the benefit.
>
> ~ # ./vdso_test_getrandom bench-single
>     vdso: 25000000 times in 4.977777162 seconds
>     libc: 25000000 times in 75.516749981 seconds
> syscall: 25000000 times in 86.842242014 seconds
>
> ~ # ./vdso_test_getrandom bench-single
>     vdso: 25000000 times in 6.473814156 seconds
>     libc: 25000000 times in 73.875109463 seconds
> syscall: 25000000 times in 71.805066229 seconds

Tried the patchset on top of

https://kernel.googlesource.com/pub/scm/linux/kernel/git/crng/random.git
(commit 963233ff013377bc2aa0d641b9efbb7fd4c2b72c (origin/master, 
origin/HEAD, master))

Results from a Power9 (PowerNV)
# ./vdso_test_getrandom bench-single
    vdso: 25000000 times in 0.787943615 seconds
    libc: 25000000 times in 14.101887252 seconds
    syscall: 25000000 times in 14.047475082 seconds

Impressive, thanks for enabling it.

Tested-by: Madhavan Srinivasan <maddy@linux.ibm.com>

> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
> v5:
> - VDSO32 for both PPC32 and PPC64 is in previous patch. This patch have the logic for VDSO64.
>
> v4:
> - Use __BIG_ENDIAN__ which is defined by GCC instead of CONFIG_CPU_BIG_ENDIAN which is unknown by selftests
> - Implement a cleaner/smaller output copy for little endian instead of keeping compat macro.
>
> v3: New (split out of previous patch)
> ---
>   arch/powerpc/Kconfig                         |  2 +-
>   arch/powerpc/kernel/vdso/Makefile            |  8 ++-
>   arch/powerpc/kernel/vdso/getrandom.S         |  8 +++
>   arch/powerpc/kernel/vdso/vdso64.lds.S        |  1 +
>   arch/powerpc/kernel/vdso/vgetrandom-chacha.S | 53 ++++++++++++++++++++
>   5 files changed, 69 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index e500a59ddecc..b45452ac4a73 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -311,7 +311,7 @@ config PPC
>   	select SYSCTL_EXCEPTION_TRACE
>   	select THREAD_INFO_IN_TASK
>   	select TRACE_IRQFLAGS_SUPPORT
> -	select VDSO_GETRANDOM			if VDSO32
> +	select VDSO_GETRANDOM
>   	#
>   	# Please keep this list sorted alphabetically.
>   	#
> diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
> index 7a4a935406d8..56fb1633529a 100644
> --- a/arch/powerpc/kernel/vdso/Makefile
> +++ b/arch/powerpc/kernel/vdso/Makefile
> @@ -9,6 +9,7 @@ obj-vdso32 = sigtramp32-32.o gettimeofday-32.o datapage-32.o cacheflush-32.o not
>   obj-vdso64 = sigtramp64-64.o gettimeofday-64.o datapage-64.o cacheflush-64.o note-64.o getcpu-64.o
>   
>   obj-vdso32 += getrandom-32.o vgetrandom-chacha-32.o
> +obj-vdso64 += getrandom-64.o vgetrandom-chacha-64.o
>   
>   ifneq ($(c-gettimeofday-y),)
>     CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
> @@ -21,6 +22,7 @@ endif
>   
>   ifneq ($(c-getrandom-y),)
>     CFLAGS_vgetrandom-32.o += -include $(c-getrandom-y)
> +  CFLAGS_vgetrandom-64.o += -include $(c-getrandom-y) $(call cc-option, -ffixed-r30)
>   endif
>   
>   # Build rules
> @@ -34,7 +36,7 @@ endif
>   targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday-32.o vgetrandom-32.o
>   targets += crtsavres-32.o
>   obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
> -targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o
> +targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o vgetrandom-64.o
>   obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
>   
>   ccflags-y := -fno-common -fno-builtin -DBUILD_VDSO
> @@ -71,7 +73,7 @@ CPPFLAGS_vdso64.lds += -P -C
>   # link rule for the .so file, .lds has to be first
>   $(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o $(obj)/vgetrandom-32.o $(obj)/crtsavres-32.o FORCE
>   	$(call if_changed,vdso32ld_and_check)
> -$(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o FORCE
> +$(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o $(obj)/vgetrandom-64.o FORCE
>   	$(call if_changed,vdso64ld_and_check)
>   
>   # assembly rules for the .S files
> @@ -87,6 +89,8 @@ $(obj-vdso64): %-64.o: %.S FORCE
>   	$(call if_changed_dep,vdso64as)
>   $(obj)/vgettimeofday-64.o: %-64.o: %.c FORCE
>   	$(call if_changed_dep,cc_o_c)
> +$(obj)/vgetrandom-64.o: %-64.o: %.c FORCE
> +	$(call if_changed_dep,cc_o_c)
>   
>   # Generate VDSO offsets using helper script
>   gen-vdso32sym := $(src)/gen_vdso32_offsets.sh
> diff --git a/arch/powerpc/kernel/vdso/getrandom.S b/arch/powerpc/kernel/vdso/getrandom.S
> index 21773ef3fc1d..a957cd2b2b03 100644
> --- a/arch/powerpc/kernel/vdso/getrandom.S
> +++ b/arch/powerpc/kernel/vdso/getrandom.S
> @@ -27,10 +27,18 @@
>     .cfi_adjust_cfa_offset PPC_MIN_STKFRM
>   	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
>     .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
> +#ifdef __powerpc64__
> +	PPC_STL		r2, PPC_MIN_STKFRM + STK_GOT(r1)
> +  .cfi_rel_offset r2, PPC_MIN_STKFRM + STK_GOT
> +#endif
>   	get_datapage	r8
>   	addi		r8, r8, VDSO_RNG_DATA_OFFSET
>   	bl		CFUNC(DOTSYM(\funct))
>   	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> +#ifdef __powerpc64__
> +	PPC_LL		r2, PPC_MIN_STKFRM + STK_GOT(r1)
> +  .cfi_restore r2
> +#endif
>   	cmpwi		r3, 0
>   	mtlr		r0
>   	addi		r1, r1, 2 * PPC_MIN_STKFRM
> diff --git a/arch/powerpc/kernel/vdso/vdso64.lds.S b/arch/powerpc/kernel/vdso/vdso64.lds.S
> index 400819258c06..9481e4b892ed 100644
> --- a/arch/powerpc/kernel/vdso/vdso64.lds.S
> +++ b/arch/powerpc/kernel/vdso/vdso64.lds.S
> @@ -123,6 +123,7 @@ VERSION
>   		__kernel_sigtramp_rt64;
>   		__kernel_getcpu;
>   		__kernel_time;
> +		__kernel_getrandom;
>   
>   	local: *;
>   	};
> diff --git a/arch/powerpc/kernel/vdso/vgetrandom-chacha.S b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
> index ac85788205cb..7f9061a9e8b4 100644
> --- a/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
> +++ b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
> @@ -124,6 +124,26 @@
>    */
>   SYM_FUNC_START(__arch_chacha20_blocks_nostack)
>   #ifdef __powerpc64__
> +	std	counter, -216(r1)
> +
> +	std	r14, -144(r1)
> +	std	r15, -136(r1)
> +	std	r16, -128(r1)
> +	std	r17, -120(r1)
> +	std	r18, -112(r1)
> +	std	r19, -104(r1)
> +	std	r20, -96(r1)
> +	std	r21, -88(r1)
> +	std	r22, -80(r1)
> +	std	r23, -72(r1)
> +	std	r24, -64(r1)
> +	std	r25, -56(r1)
> +	std	r26, -48(r1)
> +	std	r27, -40(r1)
> +	std	r28, -32(r1)
> +	std	r29, -24(r1)
> +	std	r30, -16(r1)
> +	std	r31, -8(r1)
>   #else
>   	stwu	r1, -96(r1)
>   	stw	counter, 20(r1)
> @@ -149,9 +169,13 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
>   	stw	r30, 88(r1)
>   	stw	r31, 92(r1)
>   #endif
> +#endif	/* __powerpc64__ */
>   
>   	lwz	counter0, 0(counter)
>   	lwz	counter1, 4(counter)
> +#ifdef __powerpc64__
> +	rldimi	counter0, counter1, 32, 0
> +#endif
>   	mr	idx_r0, nblocks
>   	subi	dst_bytes, dst_bytes, 4
>   
> @@ -267,12 +291,21 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
>   
>   	subic.	idx_r0, idx_r0, 1	/* subi. can't use r0 as source */
>   
> +#ifdef __powerpc64__
> +	addi	counter0, counter0, 1
> +	srdi	counter1, counter0, 32
> +#else
>   	addic	counter0, counter0, 1
>   	addze	counter1, counter1
> +#endif
>   
>   	bne	.Lblock
>   
> +#ifdef __powerpc64__
> +	ld	counter, -216(r1)
> +#else
>   	lwz	counter, 20(r1)
> +#endif
>   	stw	counter0, 0(counter)
>   	stw	counter1, 4(counter)
>   
> @@ -284,6 +317,26 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
>   	li	r11, 0
>   	li	r12, 0
>   
> +#ifdef __powerpc64__
> +	ld	r14, -144(r1)
> +	ld	r15, -136(r1)
> +	ld	r16, -128(r1)
> +	ld	r17, -120(r1)
> +	ld	r18, -112(r1)
> +	ld	r19, -104(r1)
> +	ld	r20, -96(r1)
> +	ld	r21, -88(r1)
> +	ld	r22, -80(r1)
> +	ld	r23, -72(r1)
> +	ld	r24, -64(r1)
> +	ld	r25, -56(r1)
> +	ld	r26, -48(r1)
> +	ld	r27, -40(r1)
> +	ld	r28, -32(r1)
> +	ld	r29, -24(r1)
> +	ld	r30, -16(r1)
> +	ld	r31, -8(r1)
> +#else
>   #ifdef __BIG_ENDIAN__
>   	lmw	r14, 24(r1)
>   #else

Re: [PATCH v5 0/5] Wire up getrandom() vDSO implementation on powerpc

[Jason A. Donenfeld]

Hi Christophe, Michael,

On Mon, Sep 02, 2024 at 09:17:17PM +0200, Christophe Leroy wrote:
> This series wires up getrandom() vDSO implementation on powerpc.
> 
> Tested on PPC32 on real hardware.
> Tested on PPC64 (both BE and LE) on QEMU:
> 
> Performance on powerpc 885:
> 	~# ./vdso_test_getrandom bench-single
> 	   vdso: 25000000 times in 62.938002291 seconds
> 	   libc: 25000000 times in 535.581916866 seconds
> 	syscall: 25000000 times in 531.525042806 seconds
> 
> Performance on powerpc 8321:
> 	~# ./vdso_test_getrandom bench-single
> 	   vdso: 25000000 times in 16.899318858 seconds
> 	   libc: 25000000 times in 131.050596522 seconds
> 	syscall: 25000000 times in 129.794790389 seconds
> 
> Performance on QEMU pseries:
> 	~ # ./vdso_test_getrandom bench-single
> 	   vdso: 25000000 times in 4.977777162 seconds
> 	   libc: 25000000 times in 75.516749981 seconds
> 	syscall: 25000000 times in 86.842242014 seconds

Looking good. I have no remaining nits on this patchset; it looks good
to me.

A review from Michael would be nice though (in addition to the necessary
"Ack" I need to commit this to my tree), because there are a lot of PPC
particulars that I don't know enough about to review properly. For
example, you use -ffixed-r30 on PPC64. I'm sure there's a good reason
for this, but I don't know enough to assess it. And cvdso_call I have no
idea what's going on. Etc.

But anyway, awesome work, and I look forward to the final stretches.

Jason

Re: [PATCH v5 0/5] Wire up getrandom() vDSO implementation on powerpc

[Christophe Leroy]

Le 04/09/2024 à 16:16, Jason A. Donenfeld a écrit :
> Hi Christophe, Michael,
> 
> On Mon, Sep 02, 2024 at 09:17:17PM +0200, Christophe Leroy wrote:
>> This series wires up getrandom() vDSO implementation on powerpc.
>>
>> Tested on PPC32 on real hardware.
>> Tested on PPC64 (both BE and LE) on QEMU:
>>
>> Performance on powerpc 885:
>> 	~# ./vdso_test_getrandom bench-single
>> 	   vdso: 25000000 times in 62.938002291 seconds
>> 	   libc: 25000000 times in 535.581916866 seconds
>> 	syscall: 25000000 times in 531.525042806 seconds
>>
>> Performance on powerpc 8321:
>> 	~# ./vdso_test_getrandom bench-single
>> 	   vdso: 25000000 times in 16.899318858 seconds
>> 	   libc: 25000000 times in 131.050596522 seconds
>> 	syscall: 25000000 times in 129.794790389 seconds
>>
>> Performance on QEMU pseries:
>> 	~ # ./vdso_test_getrandom bench-single
>> 	   vdso: 25000000 times in 4.977777162 seconds
>> 	   libc: 25000000 times in 75.516749981 seconds
>> 	syscall: 25000000 times in 86.842242014 seconds
> 
> Looking good. I have no remaining nits on this patchset; it looks good
> to me.
> 
> A review from Michael would be nice though (in addition to the necessary
> "Ack" I need to commit this to my tree), because there are a lot of PPC
> particulars that I don't know enough about to review properly. For
> example, you use -ffixed-r30 on PPC64. I'm sure there's a good reason
> for this, but I don't know enough to assess it. And cvdso_call I have no
> idea what's going on. Etc.

You can learn a bit more about cvdso_call in commit ce7d8056e38b 
("powerpc/vdso: Prepare for switching VDSO to generic C implementation.")

About the fixed-r30, you can learn more in commit a88603f4b92e 
("powerpc/vdso: Don't use r30 to avoid breaking Go lang")


> 
> But anyway, awesome work, and I look forward to the final stretches.

Thanks, looking forward to getting this series applied.

Christophe

Re: [PATCH v5 0/5] Wire up getrandom() vDSO implementation on powerpc

[Michael Ellerman]

"Jason A. Donenfeld" <Jason@zx2c4.com> writes:
> Hi Christophe, Michael,
>
> On Mon, Sep 02, 2024 at 09:17:17PM +0200, Christophe Leroy wrote:
>> This series wires up getrandom() vDSO implementation on powerpc.
>> 
>> Tested on PPC32 on real hardware.
>> Tested on PPC64 (both BE and LE) on QEMU:
>> 
>> Performance on powerpc 885:
>> 	~# ./vdso_test_getrandom bench-single
>> 	   vdso: 25000000 times in 62.938002291 seconds
>> 	   libc: 25000000 times in 535.581916866 seconds
>> 	syscall: 25000000 times in 531.525042806 seconds
>> 
>> Performance on powerpc 8321:
>> 	~# ./vdso_test_getrandom bench-single
>> 	   vdso: 25000000 times in 16.899318858 seconds
>> 	   libc: 25000000 times in 131.050596522 seconds
>> 	syscall: 25000000 times in 129.794790389 seconds
>> 
>> Performance on QEMU pseries:
>> 	~ # ./vdso_test_getrandom bench-single
>> 	   vdso: 25000000 times in 4.977777162 seconds
>> 	   libc: 25000000 times in 75.516749981 seconds
>> 	syscall: 25000000 times in 86.842242014 seconds
>
> Looking good. I have no remaining nits on this patchset; it looks good
> to me.
>
> A review from Michael would be nice though (in addition to the necessary
> "Ack" I need to commit this to my tree), because there are a lot of PPC
> particulars that I don't know enough about to review properly. For
> example, you use -ffixed-r30 on PPC64. I'm sure there's a good reason
> for this, but I don't know enough to assess it. And cvdso_call I have no
> idea what's going on. Etc.
 
It all looks good to me, and has survived some testing. Let's get it
merged and get some wider test coverage.

There is an existing comment in the a/p/vdso/Makefile about the
fixed-r30 thing, tldr is it's a workaround to avoid breaking old
versions of Go.

For the series:

Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

If you can include Maddy's test results from Power9 in the change log
for patch 5 that'd be nice.

cheers

Re: [PATCH v5 0/5] Wire up getrandom() vDSO implementation on powerpc

[Jason A. Donenfeld]

On Thu, Sep 05, 2024 at 10:18:40PM +1000, Michael Ellerman wrote:
> There is an existing comment in the a/p/vdso/Makefile about the
> fixed-r30 thing, tldr is it's a workaround to avoid breaking old
> versions of Go.

Thanks. Indeed, following Christophe's links yesterday, I tumbled down
that rabbit hole for a bit. Interesting how ABIs ossify unintentionally.


> For the series:
> 
> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

Excellent, queued up now.

> If you can include Maddy's test results from Power9 in the change log
> for patch 5 that'd be nice.

Was my plan exactly. I replaced the QEMU result with the PowerNV one.

Jason

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Jason A. Donenfeld]

> +/*
> + * The macro sets two stack frames, one for the caller and one for the callee
> + * because there are no requirement for the caller to set a stack frame when
> + * calling VDSO so it may have omitted to set one, especially on PPC64
> + */
> +
> +.macro cvdso_call funct
> +  .cfi_startproc
> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> +	mflr		r0
> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> +	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> +  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
> +	get_datapage	r8
> +	addi		r8, r8, VDSO_RNG_DATA_OFFSET
> +	bl		CFUNC(DOTSYM(\funct))
> +	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> +	cmpwi		r3, 0
> +	mtlr		r0
> +	addi		r1, r1, 2 * PPC_MIN_STKFRM
> +  .cfi_restore lr
> +  .cfi_def_cfa_offset 0
> +	crclr		so
> +	bgelr+
> +	crset		so
> +	neg		r3, r3
> +	blr
> +  .cfi_endproc
> +.endm

You wrote in an earlier email that this worked with time namespaces, but
in my testing that doesn't seem to be the case.

From my test harness [1]:

Normal single thread
   vdso: 25000000 times in 12.494133131 seconds
   libc: 25000000 times in 69.594625188 seconds
syscall: 25000000 times in 67.349243972 seconds
Time namespace single thread
   vdso: 25000000 times in 71.673057436 seconds
   libc: 25000000 times in 71.712774121 seconds
syscall: 25000000 times in 66.902318080 seconds

I'm seeing this on ppc, ppc64, and ppc64le.

Can you figure out what's going on and send a fix, which I'll squash
into this commit?

Jason

[1] https://git.zx2c4.com/linux-rng/commit/?h=jd/vdso-test-harness

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Jason A. Donenfeld]

On Thu, Sep 05, 2024 at 06:13:29PM +0200, Jason A. Donenfeld wrote:
> > +/*
> > + * The macro sets two stack frames, one for the caller and one for the callee
> > + * because there are no requirement for the caller to set a stack frame when
> > + * calling VDSO so it may have omitted to set one, especially on PPC64
> > + */
> > +
> > +.macro cvdso_call funct
> > +  .cfi_startproc
> > +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > +	mflr		r0
> > +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > +	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > +  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
> > +	get_datapage	r8
> > +	addi		r8, r8, VDSO_RNG_DATA_OFFSET
> > +	bl		CFUNC(DOTSYM(\funct))
> > +	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > +	cmpwi		r3, 0
> > +	mtlr		r0
> > +	addi		r1, r1, 2 * PPC_MIN_STKFRM
> > +  .cfi_restore lr
> > +  .cfi_def_cfa_offset 0
> > +	crclr		so
> > +	bgelr+
> > +	crset		so
> > +	neg		r3, r3
> > +	blr
> > +  .cfi_endproc
> > +.endm
> 
> You wrote in an earlier email that this worked with time namespaces, but
> in my testing that doesn't seem to be the case.
> 
> From my test harness [1]:
> 
> Normal single thread
>    vdso: 25000000 times in 12.494133131 seconds
>    libc: 25000000 times in 69.594625188 seconds
> syscall: 25000000 times in 67.349243972 seconds
> Time namespace single thread
>    vdso: 25000000 times in 71.673057436 seconds
>    libc: 25000000 times in 71.712774121 seconds
> syscall: 25000000 times in 66.902318080 seconds
> 
> I'm seeing this on ppc, ppc64, and ppc64le.
> 
> Can you figure out what's going on and send a fix, which I'll squash
> into this commit?

Also, FYI, I've verified that things do work on x86_64, loongarch64,
arm64, and arm64_be. It's just the ppc archs that are broken. So this
test _is_ a good one.

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Christophe Leroy]

Le 05/09/2024 à 18:13, Jason A. Donenfeld a écrit :
>> +/*
>> + * The macro sets two stack frames, one for the caller and one for the callee
>> + * because there are no requirement for the caller to set a stack frame when
>> + * calling VDSO so it may have omitted to set one, especially on PPC64
>> + */
>> +
>> +.macro cvdso_call funct
>> +  .cfi_startproc
>> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
>> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
>> +	mflr		r0
>> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
>> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
>> +	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
>> +  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
>> +	get_datapage	r8
>> +	addi		r8, r8, VDSO_RNG_DATA_OFFSET
>> +	bl		CFUNC(DOTSYM(\funct))
>> +	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
>> +	cmpwi		r3, 0
>> +	mtlr		r0
>> +	addi		r1, r1, 2 * PPC_MIN_STKFRM
>> +  .cfi_restore lr
>> +  .cfi_def_cfa_offset 0
>> +	crclr		so
>> +	bgelr+
>> +	crset		so
>> +	neg		r3, r3
>> +	blr
>> +  .cfi_endproc
>> +.endm
> 
> You wrote in an earlier email that this worked with time namespaces, but
> in my testing that doesn't seem to be the case.

Did I write that ? I can't remember and neither can I remember testing 
it with time namespaces.

> 
>  From my test harness [1]:
> 
> Normal single thread
>     vdso: 25000000 times in 12.494133131 seconds
>     libc: 25000000 times in 69.594625188 seconds
> syscall: 25000000 times in 67.349243972 seconds
> Time namespace single thread
>     vdso: 25000000 times in 71.673057436 seconds
>     libc: 25000000 times in 71.712774121 seconds
> syscall: 25000000 times in 66.902318080 seconds
> 
> I'm seeing this on ppc, ppc64, and ppc64le.

What is the command to use to test with time namespace ?

> 
> Can you figure out what's going on and send a fix, which I'll squash
> into this commit?

Sure

> 
> Jason
> 
> [1] https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.zx2c4.com%2Flinux-rng%2Fcommit%2F%3Fh%3Djd%2Fvdso-test-harness&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C59fa9061064945c73a1608dccdc5b51c%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638611496253413014%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=ZUJqhcnZL7SYkuXUIt9Nlo46sZj26VYW%2F8I%2BrBLRpBE%3D&reserved=0

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Xi Ruoyao]

On Thu, 2024-09-05 at 18:55 +0200, Christophe Leroy wrote:
> > Normal single thread
> >      vdso: 25000000 times in 12.494133131 seconds
> >      libc: 25000000 times in 69.594625188 seconds
> > syscall: 25000000 times in 67.349243972 seconds
> > Time namespace single thread
> >      vdso: 25000000 times in 71.673057436 seconds
> >      libc: 25000000 times in 71.712774121 seconds
> > syscall: 25000000 times in 66.902318080 seconds
> > 
> > I'm seeing this on ppc, ppc64, and ppc64le.
> 
> What is the command to use to test with time namespace ?

Assuming user namespace and time namespace are available:

$ unshare -r -T --boottime $((365*24*3600))

It'll start a new shell where you are pretended to be the root (i.e. the
root in the separated user namespace).  Then:

# uptime
 00:57:17 up 365 days, 57 min,  2 users,  load average: 0.19, 0.30, 0.32

So in the separated time namespace the system is pretended to have been
booted for 1 year.  Now:

# /path/to/linux.git/tools/testing/selftests/vDSO/vdso_test_getrandom bench_single
   vdso: 25000000 times in 0.419125373 seconds
   libc: 25000000 times in 5.985498234 seconds
syscall: 25000000 times in 5.993506773 seconds

This is on x86_64, indicating vDSO getrandom is fine for x86_64 in a
separated time namespace.

If user namespace isn't available (disabled building the kernel or
disabled by the security policy of some distros) use

$ sudo unshare -T --boottime $((365*24*3600))

to create the time namespace instead.  But note that with this approach
you'll be operating as the real root user and be careful not to break
things.

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Jason A. Donenfeld]

On Thu, Sep 05, 2024 at 06:55:27PM +0200, Christophe Leroy wrote:
> 
> 
> Le 05/09/2024 à 18:13, Jason A. Donenfeld a écrit :
> >> +/*
> >> + * The macro sets two stack frames, one for the caller and one for the callee
> >> + * because there are no requirement for the caller to set a stack frame when
> >> + * calling VDSO so it may have omitted to set one, especially on PPC64
> >> + */
> >> +
> >> +.macro cvdso_call funct
> >> +  .cfi_startproc
> >> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> >> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> >> +	mflr		r0
> >> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> >> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> >> +	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> >> +  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
> >> +	get_datapage	r8
> >> +	addi		r8, r8, VDSO_RNG_DATA_OFFSET
> >> +	bl		CFUNC(DOTSYM(\funct))
> >> +	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> >> +	cmpwi		r3, 0
> >> +	mtlr		r0
> >> +	addi		r1, r1, 2 * PPC_MIN_STKFRM
> >> +  .cfi_restore lr
> >> +  .cfi_def_cfa_offset 0
> >> +	crclr		so
> >> +	bgelr+
> >> +	crset		so
> >> +	neg		r3, r3
> >> +	blr
> >> +  .cfi_endproc
> >> +.endm
> > 
> > You wrote in an earlier email that this worked with time namespaces, but
> > in my testing that doesn't seem to be the case.
> 
> Did I write that ? I can't remember and neither can I remember testing 
> it with time namespaces.

It's possible I confused you with someone else? Hum. Anyway...

> >  From my test harness [1]:
> > 
> > Normal single thread
> >     vdso: 25000000 times in 12.494133131 seconds
> >     libc: 25000000 times in 69.594625188 seconds
> > syscall: 25000000 times in 67.349243972 seconds
> > Time namespace single thread
> >     vdso: 25000000 times in 71.673057436 seconds
> >     libc: 25000000 times in 71.712774121 seconds
> > syscall: 25000000 times in 66.902318080 seconds
> > 
> > I'm seeing this on ppc, ppc64, and ppc64le.
> 
> What is the command to use to test with time namespace ?

Look at the C in the commit I linked.

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Jason A. Donenfeld]

On Thu, Sep 05, 2024 at 07:03:34PM +0200, Jason A. Donenfeld wrote:
> On Thu, Sep 05, 2024 at 06:55:27PM +0200, Christophe Leroy wrote:
> > 
> > 
> > Le 05/09/2024 à 18:13, Jason A. Donenfeld a écrit :
> > >> +/*
> > >> + * The macro sets two stack frames, one for the caller and one for the callee
> > >> + * because there are no requirement for the caller to set a stack frame when
> > >> + * calling VDSO so it may have omitted to set one, especially on PPC64
> > >> + */
> > >> +
> > >> +.macro cvdso_call funct
> > >> +  .cfi_startproc
> > >> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > >> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > >> +	mflr		r0
> > >> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > >> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > >> +	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > >> +  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
> > >> +	get_datapage	r8
> > >> +	addi		r8, r8, VDSO_RNG_DATA_OFFSET
> > >> +	bl		CFUNC(DOTSYM(\funct))
> > >> +	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > >> +	cmpwi		r3, 0
> > >> +	mtlr		r0
> > >> +	addi		r1, r1, 2 * PPC_MIN_STKFRM
> > >> +  .cfi_restore lr
> > >> +  .cfi_def_cfa_offset 0
> > >> +	crclr		so
> > >> +	bgelr+
> > >> +	crset		so
> > >> +	neg		r3, r3
> > >> +	blr
> > >> +  .cfi_endproc
> > >> +.endm
> > > 
> > > You wrote in an earlier email that this worked with time namespaces, but
> > > in my testing that doesn't seem to be the case.
> > 
> > Did I write that ? I can't remember and neither can I remember testing 
> > it with time namespaces.
> 
> It's possible I confused you with someone else? Hum. Anyway...
> 
> > >  From my test harness [1]:
> > > 
> > > Normal single thread
> > >     vdso: 25000000 times in 12.494133131 seconds
> > >     libc: 25000000 times in 69.594625188 seconds
> > > syscall: 25000000 times in 67.349243972 seconds
> > > Time namespace single thread
> > >     vdso: 25000000 times in 71.673057436 seconds
> > >     libc: 25000000 times in 71.712774121 seconds
> > > syscall: 25000000 times in 66.902318080 seconds
> > > 
> > > I'm seeing this on ppc, ppc64, and ppc64le.
> > 
> > What is the command to use to test with time namespace ?
> 
> Look at the C in the commit I linked.

The below also seems to work well for testing on x86. I'll clean that up
and send a patch to the list.

diff --git a/tools/testing/selftests/vDSO/vdso_test_getrandom.c b/tools/testing/selftests/vDSO/vdso_test_getrandom.c
index 8866b65a4605..4df80f769aa7 100644
--- a/tools/testing/selftests/vDSO/vdso_test_getrandom.c
+++ b/tools/testing/selftests/vDSO/vdso_test_getrandom.c
@@ -16,8 +16,11 @@
 #include <sys/mman.h>
 #include <sys/random.h>
 #include <sys/syscall.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
 #include <sys/types.h>
 #include <linux/random.h>
+#include <linux/ptrace.h>

 #include "../kselftest.h"
 #include "parse_vdso.h"
@@ -239,9 +242,10 @@ static void fill(void)
 static void kselftest(void)
 {
 	uint8_t weird_size[1263];
+	pid_t child;

 	ksft_print_header();
-	ksft_set_plan(1);
+	ksft_set_plan(2);

 	for (size_t i = 0; i < 1000; ++i) {
 		ssize_t ret = vgetrandom(weird_size, sizeof(weird_size), 0);
@@ -250,6 +254,39 @@ static void kselftest(void)
 	}

 	ksft_test_result_pass("getrandom: PASS\n");
+
+	assert(unshare(CLONE_NEWTIME) == 0);
+	child = fork();
+	assert(child >= 0);
+
+	if (!child) {
+		vgetrandom_init();
+		child = getpid();
+		assert(ptrace(PTRACE_TRACEME, 0, NULL, NULL) == 0);
+		assert(kill(child, SIGSTOP) == 0);
+		assert(vgetrandom(weird_size, sizeof(weird_size), 0) == sizeof(weird_size));
+		_exit(0);
+	}
+	for (;;) {
+		struct ptrace_syscall_info info = { 0 };
+		int status, ret;
+		assert(waitpid(child, &status, 0) >= 0);
+		if (WIFEXITED(status))
+			break;
+		assert(WIFSTOPPED(status));
+		if (WSTOPSIG(status) == SIGSTOP)
+			assert(ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACESYSGOOD) == 0);
+		else if (WSTOPSIG(status) == SIGTRAP | 0x80) {
+			assert(ptrace(PTRACE_GET_SYSCALL_INFO, child, sizeof(info), &info) > 0);
+			if (info.entry.nr == __NR_getrandom &&
+			    ((void *)info.entry.args[0] == &weird_size && info.entry.args[1] == sizeof(weird_size)))
+				exit(KSFT_FAIL);
+		}
+		assert(ptrace(PTRACE_SYSCALL, child, 0, 0) == 0);
+	}
+
+	ksft_test_result_pass("getrandom timens: PASS\n");
+
 	exit(KSFT_PASS);
 }

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Jason A. Donenfeld]

On Thu, Sep 05, 2024 at 06:13:29PM +0200, Jason A. Donenfeld wrote:
> > +/*
> > + * The macro sets two stack frames, one for the caller and one for the callee
> > + * because there are no requirement for the caller to set a stack frame when
> > + * calling VDSO so it may have omitted to set one, especially on PPC64
> > + */
> > +
> > +.macro cvdso_call funct
> > +  .cfi_startproc
> > +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > +	mflr		r0
> > +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > +	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > +  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
> > +	get_datapage	r8
> > +	addi		r8, r8, VDSO_RNG_DATA_OFFSET
> > +	bl		CFUNC(DOTSYM(\funct))
> > +	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > +	cmpwi		r3, 0
> > +	mtlr		r0
> > +	addi		r1, r1, 2 * PPC_MIN_STKFRM
> > +  .cfi_restore lr
> > +  .cfi_def_cfa_offset 0
> > +	crclr		so
> > +	bgelr+
> > +	crset		so
> > +	neg		r3, r3
> > +	blr
> > +  .cfi_endproc
> > +.endm
> 
> Can you figure out what's going on and send a fix, which I'll squash
> into this commit?

This doesn't work, but I wonder if something like it is what we want. I
need to head out for the day, but here's what I've got. It's all wrong
but might be of interest.

diff --git a/arch/powerpc/include/asm/vdso/getrandom.h b/arch/powerpc/include/asm/vdso/getrandom.h
index 501d6bb14e8a..acb271709d30 100644
--- a/arch/powerpc/include/asm/vdso/getrandom.h
+++ b/arch/powerpc/include/asm/vdso/getrandom.h
@@ -47,7 +47,8 @@ static __always_inline struct vdso_rng_data *__arch_get_vdso_rng_data(void)
 }

 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);
+			     size_t opaque_len, const struct vdso_data *vd,
+			     const struct vdso_rng_data *vrd);

 #endif /* !__ASSEMBLY__ */

diff --git a/arch/powerpc/kernel/vdso/getrandom.S b/arch/powerpc/kernel/vdso/getrandom.S
index a957cd2b2b03..bc49eb87cfd1 100644
--- a/arch/powerpc/kernel/vdso/getrandom.S
+++ b/arch/powerpc/kernel/vdso/getrandom.S
@@ -32,7 +32,7 @@
   .cfi_rel_offset r2, PPC_MIN_STKFRM + STK_GOT
 #endif
 	get_datapage	r8
-	addi		r8, r8, VDSO_RNG_DATA_OFFSET
+	addi		r9, r8, VDSO_RNG_DATA_OFFSET
 	bl		CFUNC(DOTSYM(\funct))
 	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
 #ifdef __powerpc64__
diff --git a/arch/powerpc/kernel/vdso/vgetrandom.c b/arch/powerpc/kernel/vdso/vgetrandom.c
index 5f855d45fb7b..408c76036868 100644
--- a/arch/powerpc/kernel/vdso/vgetrandom.c
+++ b/arch/powerpc/kernel/vdso/vgetrandom.c
@@ -8,7 +8,10 @@
 #include <linux/types.h>

 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)
+			     size_t opaque_len, const struct vdso_data *vd,
+			     const struct vdso_rng_data *vrd)
 {
-	return __cvdso_getrandom_data(vd, buffer, len, flags, opaque_state, opaque_len);
+	if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
+		vrd = (void *)vrd + (1UL << CONFIG_PAGE_SHIFT);
+	return __cvdso_getrandom_data(vrd, buffer, len, flags, opaque_state, opaque_len);
 }

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Jason A. Donenfeld]

On Thu, Sep 05, 2024 at 10:41:40PM +0200, Jason A. Donenfeld wrote:
> On Thu, Sep 05, 2024 at 06:13:29PM +0200, Jason A. Donenfeld wrote:
> > > +/*
> > > + * The macro sets two stack frames, one for the caller and one for the callee
> > > + * because there are no requirement for the caller to set a stack frame when
> > > + * calling VDSO so it may have omitted to set one, especially on PPC64
> > > + */
> > > +
> > > +.macro cvdso_call funct
> > > +  .cfi_startproc
> > > +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > > +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > > +	mflr		r0
> > > +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > > +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > > +	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > > +  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
> > > +	get_datapage	r8
> > > +	addi		r8, r8, VDSO_RNG_DATA_OFFSET
> > > +	bl		CFUNC(DOTSYM(\funct))
> > > +	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > > +	cmpwi		r3, 0
> > > +	mtlr		r0
> > > +	addi		r1, r1, 2 * PPC_MIN_STKFRM
> > > +  .cfi_restore lr
> > > +  .cfi_def_cfa_offset 0
> > > +	crclr		so
> > > +	bgelr+
> > > +	crset		so
> > > +	neg		r3, r3
> > > +	blr
> > > +  .cfi_endproc
> > > +.endm
> > 
> > Can you figure out what's going on and send a fix, which I'll squash
> > into this commit?
> 
> This doesn't work, but I wonder if something like it is what we want. I
> need to head out for the day, but here's what I've got. It's all wrong
> but might be of interest.

Oh, I just got one small detail wrong before. The below actually works,
and uses the same strategy as on arm64.

Let me know if you'd like me to fix up this commit with the below patch,
or if you have another way you'd like to go about it.

diff --git a/arch/powerpc/include/asm/vdso/getrandom.h b/arch/powerpc/include/asm/vdso/getrandom.h
index 501d6bb14e8a..acb271709d30 100644
--- a/arch/powerpc/include/asm/vdso/getrandom.h
+++ b/arch/powerpc/include/asm/vdso/getrandom.h
@@ -47,7 +47,8 @@ static __always_inline struct vdso_rng_data *__arch_get_vdso_rng_data(void)
 }

 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);
+			     size_t opaque_len, const struct vdso_data *vd,
+			     const struct vdso_rng_data *vrd);

 #endif /* !__ASSEMBLY__ */

diff --git a/arch/powerpc/kernel/vdso/getrandom.S b/arch/powerpc/kernel/vdso/getrandom.S
index a957cd2b2b03..64cc1fad3ccc 100644
--- a/arch/powerpc/kernel/vdso/getrandom.S
+++ b/arch/powerpc/kernel/vdso/getrandom.S
@@ -32,7 +32,8 @@
   .cfi_rel_offset r2, PPC_MIN_STKFRM + STK_GOT
 #endif
 	get_datapage	r8
-	addi		r8, r8, VDSO_RNG_DATA_OFFSET
+	addi		r9, r8, VDSO_RNG_DATA_OFFSET
+	addi		r8, r8, VDSO_DATA_OFFSET
 	bl		CFUNC(DOTSYM(\funct))
 	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
 #ifdef __powerpc64__
diff --git a/arch/powerpc/kernel/vdso/vgetrandom.c b/arch/powerpc/kernel/vdso/vgetrandom.c
index 5f855d45fb7b..408c76036868 100644
--- a/arch/powerpc/kernel/vdso/vgetrandom.c
+++ b/arch/powerpc/kernel/vdso/vgetrandom.c
@@ -8,7 +8,10 @@
 #include <linux/types.h>

 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)
+			     size_t opaque_len, const struct vdso_data *vd,
+			     const struct vdso_rng_data *vrd)
 {
-	return __cvdso_getrandom_data(vd, buffer, len, flags, opaque_state, opaque_len);
+	if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
+		vrd = (void *)vrd + (1UL << CONFIG_PAGE_SHIFT);
+	return __cvdso_getrandom_data(vrd, buffer, len, flags, opaque_state, opaque_len);
 }

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Jason A. Donenfeld]

On Fri, Sep 06, 2024 at 04:48:28AM +0200, Jason A. Donenfeld wrote:
> On Thu, Sep 05, 2024 at 10:41:40PM +0200, Jason A. Donenfeld wrote:
> > On Thu, Sep 05, 2024 at 06:13:29PM +0200, Jason A. Donenfeld wrote:
> > > > +/*
> > > > + * The macro sets two stack frames, one for the caller and one for the callee
> > > > + * because there are no requirement for the caller to set a stack frame when
> > > > + * calling VDSO so it may have omitted to set one, especially on PPC64
> > > > + */
> > > > +
> > > > +.macro cvdso_call funct
> > > > +  .cfi_startproc
> > > > +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > > > +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > > > +	mflr		r0
> > > > +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
> > > > +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
> > > > +	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > > > +  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
> > > > +	get_datapage	r8
> > > > +	addi		r8, r8, VDSO_RNG_DATA_OFFSET
> > > > +	bl		CFUNC(DOTSYM(\funct))
> > > > +	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> > > > +	cmpwi		r3, 0
> > > > +	mtlr		r0
> > > > +	addi		r1, r1, 2 * PPC_MIN_STKFRM
> > > > +  .cfi_restore lr
> > > > +  .cfi_def_cfa_offset 0
> > > > +	crclr		so
> > > > +	bgelr+
> > > > +	crset		so
> > > > +	neg		r3, r3
> > > > +	blr
> > > > +  .cfi_endproc
> > > > +.endm
> > > 
> > > Can you figure out what's going on and send a fix, which I'll squash
> > > into this commit?
> > 
> > This doesn't work, but I wonder if something like it is what we want. I
> > need to head out for the day, but here's what I've got. It's all wrong
> > but might be of interest.
> 
> Oh, I just got one small detail wrong before. The below actually works,
> and uses the same strategy as on arm64.
> 
> Let me know if you'd like me to fix up this commit with the below patch,
> or if you have another way you'd like to go about it.

And here's the much shorter version in assembly, which maybe you prefer.
Also works, and is a bit less invasive than the other thing.

diff --git a/arch/powerpc/kernel/vdso/getrandom.S b/arch/powerpc/kernel/vdso/getrandom.S
index a957cd2b2b03..070daba2d547 100644
--- a/arch/powerpc/kernel/vdso/getrandom.S
+++ b/arch/powerpc/kernel/vdso/getrandom.S
@@ -32,6 +32,14 @@
   .cfi_rel_offset r2, PPC_MIN_STKFRM + STK_GOT
 #endif
 	get_datapage	r8
+#ifdef CONFIG_TIME_NS
+	lis		r10, 0x7fff
+	ori		r10, r10, 0xffff
+	lwz		r9, VDSO_DATA_OFFSET + 4(r8)
+	cmpw		r9, r10
+	bne		+8
+	addi		r8, r8, (1 << CONFIG_PAGE_SHIFT)
+#endif
 	addi		r8, r8, VDSO_RNG_DATA_OFFSET
 	bl		CFUNC(DOTSYM(\funct))
 	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)

Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

[Christophe Leroy]

Hi Jason,

Le 06/09/2024 à 05:24, Jason A. Donenfeld a écrit :
> On Fri, Sep 06, 2024 at 04:48:28AM +0200, Jason A. Donenfeld wrote:
>> On Thu, Sep 05, 2024 at 10:41:40PM +0200, Jason A. Donenfeld wrote:
>>> On Thu, Sep 05, 2024 at 06:13:29PM +0200, Jason A. Donenfeld wrote:
>>>>> +/*
>>>>> + * The macro sets two stack frames, one for the caller and one for the callee
>>>>> + * because there are no requirement for the caller to set a stack frame when
>>>>> + * calling VDSO so it may have omitted to set one, especially on PPC64
>>>>> + */
>>>>> +
>>>>> +.macro cvdso_call funct
>>>>> +  .cfi_startproc
>>>>> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
>>>>> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
>>>>> +	mflr		r0
>>>>> +	PPC_STLU	r1, -PPC_MIN_STKFRM(r1)
>>>>> +  .cfi_adjust_cfa_offset PPC_MIN_STKFRM
>>>>> +	PPC_STL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
>>>>> +  .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
>>>>> +	get_datapage	r8
>>>>> +	addi		r8, r8, VDSO_RNG_DATA_OFFSET
>>>>> +	bl		CFUNC(DOTSYM(\funct))
>>>>> +	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
>>>>> +	cmpwi		r3, 0
>>>>> +	mtlr		r0
>>>>> +	addi		r1, r1, 2 * PPC_MIN_STKFRM
>>>>> +  .cfi_restore lr
>>>>> +  .cfi_def_cfa_offset 0
>>>>> +	crclr		so
>>>>> +	bgelr+
>>>>> +	crset		so
>>>>> +	neg		r3, r3
>>>>> +	blr
>>>>> +  .cfi_endproc
>>>>> +.endm
>>>>
>>>> Can you figure out what's going on and send a fix, which I'll squash
>>>> into this commit?
>>>
>>> This doesn't work, but I wonder if something like it is what we want. I
>>> need to head out for the day, but here's what I've got. It's all wrong
>>> but might be of interest.
>>
>> Oh, I just got one small detail wrong before. The below actually works,
>> and uses the same strategy as on arm64.
>>
>> Let me know if you'd like me to fix up this commit with the below patch,
>> or if you have another way you'd like to go about it.
> 
> And here's the much shorter version in assembly, which maybe you prefer.
> Also works, and is a bit less invasive than the other thing.
> 
> diff --git a/arch/powerpc/kernel/vdso/getrandom.S b/arch/powerpc/kernel/vdso/getrandom.S
> index a957cd2b2b03..070daba2d547 100644
> --- a/arch/powerpc/kernel/vdso/getrandom.S
> +++ b/arch/powerpc/kernel/vdso/getrandom.S
> @@ -32,6 +32,14 @@
>     .cfi_rel_offset r2, PPC_MIN_STKFRM + STK_GOT
>   #endif
>   	get_datapage	r8
> +#ifdef CONFIG_TIME_NS
> +	lis		r10, 0x7fff
> +	ori		r10, r10, 0xffff
> +	lwz		r9, VDSO_DATA_OFFSET + 4(r8)
> +	cmpw		r9, r10
> +	bne		+8
> +	addi		r8, r8, (1 << CONFIG_PAGE_SHIFT)
> +#endif
>   	addi		r8, r8, VDSO_RNG_DATA_OFFSET
>   	bl		CFUNC(DOTSYM(\funct))
>   	PPC_LL		r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
> 

Thanks for looking.

I came to more or less the same solutions thnt you with the following 
that seems to work:

diff --git a/arch/powerpc/kernel/vdso/vgetrandom.c 
b/arch/powerpc/kernel/vdso/vgetrandom.c
index 5f855d45fb7b..9705344d39d0 100644
--- a/arch/powerpc/kernel/vdso/vgetrandom.c
+++ b/arch/powerpc/kernel/vdso/vgetrandom.c
@@ -4,11 +4,19 @@
   *
   * Copyright (C) 2024 Christophe Leroy <christophe.leroy@csgroup.eu>, 
CS GROUP France
   */
+#include <linux/container_of.h>
  #include <linux/time.h>
  #include <linux/types.h>

+#include <asm/vdso_datapage.h>
+
  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)
  {
+	struct vdso_arch_data *arch_data = container_of(vd, struct 
vdso_arch_data, rng_data);
+
+	if (IS_ENABLED(CONFIG_TIME_NS) && arch_data->data[0].clock_mode == 
VDSO_CLOCKMODE_TIMENS)
+		vd = (void *)vd + (1UL << CONFIG_PAGE_SHIFT);
+
  	return __cvdso_getrandom_data(vd, buffer, len, flags, opaque_state, 
opaque_len);
  }


However, if we have this problem with __kernel_getrandom, don't we also 
have it with: ?
		__kernel_get_syscall_map;
		__kernel_get_tbfreq;
		__kernel_sync_dicache;

If they are also affected, then get_page macro is the place to fix.

I will check all of this now and keep you updated before noon (Paris Time).

Christophe