[PATCH v3 0/5] Wire up getrandom() vDSO implementation on powerpc

[PATCH v3 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

In order to run selftests, some fixes are needed, see
https://lore.kernel.org/linuxppc-dev/6c5da802e72befecfa09046c489aa45d934d611f.1725020674.git.christophe.leroy@csgroup.eu/

Those selftest fixes are independant and are not required to apply
and use this series.

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 PPC32
  powerpc/vdso: Wire up getrandom() vDSO implementation on PPC64

 arch/powerpc/Kconfig                         |   1 +
 arch/powerpc/include/asm/asm-compat.h        |   8 +
 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 | 299 +++++++++++++++++++
 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        |   4 +
 19 files changed, 492 insertions(+), 42 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 v3 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.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
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

Re: [PATCH v3 1/5] mm: Define VM_DROPPABLE for powerpc/32

[Michael Ellerman]

Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> 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.

Also, there can't be any existing users of VM_SAO on 32-bit, because PROT_SAO
(which maps to VM_SAO) is only accepted on CPUs that support SAO, and
those CPUs are all 64-bit.

cheers

[PATCH v3 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 v3 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 v3 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on PPC32

[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

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v3:
- Preserve r13, implies saving r5 on stack
- Split PPC64 implementation out.
---
 arch/powerpc/Kconfig                         |   1 +
 arch/powerpc/include/asm/asm-compat.h        |   8 +
 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            |  12 +-
 arch/powerpc/kernel/vdso/getrandom.S         |  50 +++++
 arch/powerpc/kernel/vdso/vdso32.lds.S        |   1 +
 arch/powerpc/kernel/vdso/vgetrandom-chacha.S | 201 +++++++++++++++++++
 arch/powerpc/kernel/vdso/vgetrandom.c        |  14 ++
 tools/arch/powerpc/vdso                      |   1 +
 tools/testing/selftests/vDSO/Makefile        |   4 +
 13 files changed, 353 insertions(+), 2 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..54b270ef18b1 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 PPC32
 	#
 	# Please keep this list sorted alphabetically.
 	#
diff --git a/arch/powerpc/include/asm/asm-compat.h b/arch/powerpc/include/asm/asm-compat.h
index b0b209c1df50..cce8c31b1b33 100644
--- a/arch/powerpc/include/asm/asm-compat.h
+++ b/arch/powerpc/include/asm/asm-compat.h
@@ -59,4 +59,12 @@
 
 #endif
 
+#ifdef __BIG_ENDIAN__
+#define LWZX_LE	stringify_in_c(lwbrx)
+#define STWX_LE	stringify_in_c(stwbrx)
+#else
+#define LWZX_LE	stringify_in_c(lwzx)
+#define STWX_LE	stringify_in_c(stwx)
+#endif
+
 #endif /* _ASM_POWERPC_ASM_COMPAT_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..fa0b9b3b51af 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
@@ -25,7 +31,7 @@ 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
@@ -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..a3475b9e8c10
--- /dev/null
+++ b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
@@ -0,0 +1,201 @@
+/* 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>
+
+.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 16+a1 16+b1 16+c1 16+d1 16+a2 16+b2 16+c2 16+d2 \
+		      16+a3 16+b3 16+c3 16+d3 16+a4 16+b4 16+c4 16+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)
+	stwu	r1, -96(r1)
+	stw	r5, 20(r1)
+	stmw	r14, 24(r1)
+	li	r31, 4
+	LWZX_LE	r14, 0, r5
+	LWZX_LE	r15, r31, r5
+	mr	r0, r6
+
+	lwz	r5, 0(r4)
+	lwz	r6, 4(r4)
+	lwz	r7, 8(r4)
+	lwz	r8, 12(r4)
+	lwz	r9, 16(r4)
+	lwz	r10, 20(r4)
+	lwz	r11, 24(r4)
+	lwz	r12, 28(r4)
+
+	li	r4, 4
+.Lblock:
+	li	r31, 10
+
+	lis	r16, 0x6170
+	lis	r17, 0x3320
+	lis	r18, 0x7962
+	lis	r19, 0x6b20
+	addi	r16, r16, 0x7865
+	addi	r17, r17, 0x646e
+	addi	r18, r18, 0x2d32
+	addi	r19, r19, 0x6574
+
+	mtctr	r31
+
+	mr	r20, r5
+	mr	r21, r6
+	mr	r22, r7
+	mr	r23, r8
+	mr	r24, r9
+	mr	r25, r10
+	mr	r26, r11
+	mr	r27, r12
+
+	mr	r28, r14
+	mr	r29, r15
+	li	r30, 0
+	li	r31, 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	r16, r16, 0x6170
+	addis	r17, r17, 0x3320
+	addis	r18, r18, 0x7962
+	addis	r19, r19, 0x6b20
+	addi	r16, r16, 0x7865
+	addi	r17, r17, 0x646e
+	addi	r18, r18, 0x2d32
+	addi	r19, r19, 0x6574
+
+	add	r20, r20, r5
+	add	r21, r21, r6
+	add	r22, r22, r7
+	add	r23, r23, r8
+	add	r24, r24, r9
+	add	r25, r25, r10
+	add	r26, r26, r11
+	add	r27, r27, r12
+
+	add	r28, r28, r14
+	add	r29, r29, r15
+
+	STWX_LE	r16, 0, r3
+	STWX_LE	r17, r4, r3
+	addi	r3, r3, 8
+	STWX_LE	r18, 0, r3
+	STWX_LE	r19, r4, r3
+	addi	r3, r3, 8
+	STWX_LE	r20, 0, r3
+	STWX_LE	r21, r4, r3
+	addi	r3, r3, 8
+	STWX_LE	r22, 0, r3
+	STWX_LE	r23, r4, r3
+	addi	r3, r3, 8
+	STWX_LE	r24, 0, r3
+	STWX_LE	r25, r4, r3
+	addi	r3, r3, 8
+	STWX_LE	r26, 0, r3
+	STWX_LE	r27, r4, r3
+	addi	r3, r3, 8
+	STWX_LE	r28, 0, r3
+	STWX_LE	r29, r4, r3
+	addi	r3, r3, 8
+	STWX_LE	r30, 0, r3
+	STWX_LE	r31, r4, r3
+	addi	r3, r3, 8
+
+	addic	r14, r14, 1
+	addze	r15, r15
+
+	subic.	r0, r0, 1	/* subi. can't use r0 as source */
+	bne	.Lblock
+
+	lwz	r5, 20(r1)
+	STWX_LE	r14, 0, r5
+	STWX_LE	r15, r4, r5
+
+	li	r6, 0
+	li	r7, 0
+	li	r8, 0
+	li	r9, 0
+	li	r10, 0
+	li	r11, 0
+	li	r12, 0
+
+	lmw	r14, 24(r1)
+	addi	r1, r1, 96
+	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..d31004bf8f55
--- /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 e21e78aae24d..e57dcefa1988 100644
--- a/tools/testing/selftests/vDSO/Makefile
+++ b/tools/testing/selftests/vDSO/Makefile
@@ -14,6 +14,10 @@ ifeq ($(uname_M),x86_64)
 TEST_GEN_PROGS += vdso_test_getrandom
 TEST_GEN_PROGS += vdso_test_chacha
 endif
+ifeq ($(ARCH),powerpc)
+TEST_GEN_PROGS += vdso_test_getrandom
+TEST_GEN_PROGS += vdso_test_chacha
+endif
 
 CFLAGS := -std=gnu99
 
-- 
2.44.0

Re: [PATCH v3 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on PPC32

[Jason A. Donenfeld]

On Fri, Aug 30, 2024 at 05:57:08PM +0200, Christophe Leroy wrote:
> + *	r5: 8-byte counter input/output (saved on stack)
> + *
> + *	r14-r15: counter
> + */
> +SYM_FUNC_START(__arch_chacha20_blocks_nostack)
> +	stwu	r1, -96(r1)
> +	stw	r5, 20(r1)
> +	stmw	r14, 24(r1)
> +	li	r31, 4
> +	LWZX_LE	r14, 0, r5
> +	LWZX_LE	r15, r31, r5

Why swap endian on the counter?

Re: [PATCH v3 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on PPC32

[Christophe Leroy]

Le 30/08/2024 à 18:14, Jason A. Donenfeld a écrit :
> On Fri, Aug 30, 2024 at 05:57:08PM +0200, Christophe Leroy wrote:
>> + *	r5: 8-byte counter input/output (saved on stack)
>> + *
>> + *	r14-r15: counter
>> + */
>> +SYM_FUNC_START(__arch_chacha20_blocks_nostack)
>> +	stwu	r1, -96(r1)
>> +	stw	r5, 20(r1)
>> +	stmw	r14, 24(r1)
>> +	li	r31, 4
>> +	LWZX_LE	r14, 0, r5
>> +	LWZX_LE	r15, r31, r5
> 
> Why swap endian on the counter?

Unlike the keys, the counter is passed to the function as an u8*, not as 
a u64*, so I thought it was raw data in little endian order, same as 
when using Sodium. Is it wrong ?

Christophe

Re: [PATCH v3 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on PPC32

[Christophe Leroy]

Le 30/08/2024 à 18:42, Christophe Leroy a écrit :
> 
> 
> Le 30/08/2024 à 18:14, Jason A. Donenfeld a écrit :
>> On Fri, Aug 30, 2024 at 05:57:08PM +0200, Christophe Leroy wrote:
>>> + *    r5: 8-byte counter input/output (saved on stack)
>>> + *
>>> + *    r14-r15: counter
>>> + */
>>> +SYM_FUNC_START(__arch_chacha20_blocks_nostack)
>>> +    stwu    r1, -96(r1)
>>> +    stw    r5, 20(r1)
>>> +    stmw    r14, 24(r1)
>>> +    li    r31, 4
>>> +    LWZX_LE    r14, 0, r5
>>> +    LWZX_LE    r15, r31, r5
>>
>> Why swap endian on the counter?
> 
> Unlike the keys, the counter is passed to the function as an u8*, not as 
> a u64*, so I thought it was raw data in little endian order, same as 
> when using Sodium. Is it wrong ?

Hum ..... I looked again and it seems it is already a u32 *. Looks like 
I mis-read the 8-byte comment. Or I did it right in the begining then I 
swapped it at the same time as I swapped the keys after my first test 
when the selftest was using Sodium. I can't remember. I'll fix it.

Christophe

Re: [PATCH v3 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on PPC32

[Jason A. Donenfeld]

On Fri, Aug 30, 2024 at 05:57:08PM +0200, Christophe Leroy wrote:
> @@ -14,6 +14,10 @@ ifeq ($(uname_M),x86_64)
>  TEST_GEN_PROGS += vdso_test_getrandom
>  TEST_GEN_PROGS += vdso_test_chacha
>  endif
> +ifeq ($(ARCH),powerpc)
> +TEST_GEN_PROGS += vdso_test_getrandom
> +TEST_GEN_PROGS += vdso_test_chacha
> +endif

FYI, as of [1], you should now be able to add powerpc to the filter list
instead of having to duplicate a new stanza:

[1] https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git/commit/?id=bbaae98172ed284fc0d5d39cc0d68f5d06164f06

Re: [PATCH v3 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on PPC32

[Christophe Leroy]

Le 30/08/2024 à 18:17, Jason A. Donenfeld a écrit :
> On Fri, Aug 30, 2024 at 05:57:08PM +0200, Christophe Leroy wrote:
>> @@ -14,6 +14,10 @@ ifeq ($(uname_M),x86_64)
>>   TEST_GEN_PROGS += vdso_test_getrandom
>>   TEST_GEN_PROGS += vdso_test_chacha
>>   endif
>> +ifeq ($(ARCH),powerpc)
>> +TEST_GEN_PROGS += vdso_test_getrandom
>> +TEST_GEN_PROGS += vdso_test_chacha
>> +endif
> 
> FYI, as of [1], you should now be able to add powerpc to the filter list
> instead of having to duplicate a new stanza:
> 
> [1] https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fcrng%2Frandom.git%2Fcommit%2F%3Fid%3Dbbaae98172ed284fc0d5d39cc0d68f5d06164f06&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C4f51736c027a44cc7df908dcc90f46d6%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638606314665557021%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=UtLdKTuEaZVhsguKa7kX1TBJ%2BvvQtl7DmU9hSBeThWo%3D&reserved=0

I'm a bit sceptic with that commit. IIUC you are changing the meaning of 
$ARCH. How does that fit with the $ARCH we give when we cross-build or 
with the ARCH which is set by the top-level Makefile in 
tools/testing/selftests ?

Also, wouldn't there be a way to use scripts/subarch.include instead of 
opencoding ?

Afterall, would it be a problem to build it even for i386 ? It should 
now be ignored anyway with your new commit f78280b1a3ce ("selftests: 
vDSO: skip getrandom test if architecture is unsupported")

Christophe

[PATCH v3 5/5] powerpc/vdso: Wire up getrandom() vDSO implementation on PPC64

[Christophe Leroy]

Extend getrandom() vDSO implementation to powerpc64.

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>
---
v3: New (split out of previous patch)
---
 arch/powerpc/Kconfig                         |  2 +-
 arch/powerpc/include/asm/mman.h              |  2 +-
 arch/powerpc/kernel/vdso/Makefile            | 10 +-
 arch/powerpc/kernel/vdso/getrandom.S         |  8 ++
 arch/powerpc/kernel/vdso/vdso64.lds.S        |  1 +
 arch/powerpc/kernel/vdso/vgetrandom-chacha.S | 98 ++++++++++++++++++++
 6 files changed, 116 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 54b270ef18b1..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 PPC32
+	select VDSO_GETRANDOM
 	#
 	# 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/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index fa0b9b3b51af..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
@@ -34,10 +36,10 @@ 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
+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
@@ -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 a3475b9e8c10..c9d4c5b38242 100644
--- a/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
+++ b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
@@ -79,12 +79,59 @@
  *	r16-r31: state
  */
 SYM_FUNC_START(__arch_chacha20_blocks_nostack)
+#ifdef __powerpc64__
+	std	r5, -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	r5, 20(r1)
+#if defined(CONFIG_CPU_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
+#endif
 	li	r31, 4
 	LWZX_LE	r14, 0, r5
 	LWZX_LE	r15, r31, r5
+#ifdef __powerpc64__
+	rldimi	r14, r15, 32, 0
+#endif
 	mr	r0, r6
 
 	lwz	r5, 0(r4)
@@ -177,13 +224,22 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 	STWX_LE	r31, r4, r3
 	addi	r3, r3, 8
 
+#ifdef __powerpc64__
+	addi	r14, r14, 1
+	srdi	r15, r14, 32
+#else
 	addic	r14, r14, 1
 	addze	r15, r15
+#endif
 
 	subic.	r0, r0, 1	/* subi. can't use r0 as source */
 	bne	.Lblock
 
+#ifdef __powerpc64__
+	ld	r5, -216(r1)
+#else
 	lwz	r5, 20(r1)
+#endif
 	STWX_LE	r14, 0, r5
 	STWX_LE	r15, r4, r5
 
@@ -195,7 +251,49 @@ 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
+#if defined(CONFIG_CPU_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
 	blr
 SYM_FUNC_END(__arch_chacha20_blocks_nostack)
-- 
2.44.0