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

Madhavan Srinivasan <maddy@xxxxxxxxxxxxx> · Wed, 4 Sep 2024 17:16:21 +0530

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@xxxxxxxxxxxxx>

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







