[PATCH v2 1/4] ppc64le: Revert "powerpc: Optimized strncmp for power10" (CVE-2025-5745)
Siddhesh Poyarekar
siddhesh@gotplt.org
Mon Jun 16 21:58:08 GMT 2025
I verified that the reverts are clean by applying these commits and then
running this command:
git log --pretty=oneline HEAD~4..HEAD | awk '{print $1}' |
while read ref; do
diff -u \
<(git show -R --color=never \
$(git show $ref | sed -n 's/This reverts commit \(.*\)/\1/p')) \
<(git show --color=never $ref) | less;
done
and confirmed that barring minor differences in Makefile contexts (which
is expected), they are all straight reverts.
Thanks,
Sid
On 2025-06-16 16:20, Carlos O'Donell wrote:
> This reverts commit 23f0d81608d0ca6379894ef81670cf30af7fd081
>
> Reason for revert: Power10 strncmp clobbers non-volatile vector
> registers (Bug 33060)
>
> Tested on ppc64le with no regressions.
> ---
OK.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
> .../powerpc/powerpc64/le/power10/strncmp.S | 271 ------------------
> sysdeps/powerpc/powerpc64/multiarch/Makefile | 2 +-
> .../powerpc64/multiarch/ifunc-impl-list.c | 3 -
> .../powerpc64/multiarch/strncmp-power10.S | 25 --
> sysdeps/powerpc/powerpc64/multiarch/strncmp.c | 4 -
> 5 files changed, 1 insertion(+), 304 deletions(-)
> delete mode 100644 sysdeps/powerpc/powerpc64/le/power10/strncmp.S
> delete mode 100644 sysdeps/powerpc/powerpc64/multiarch/strncmp-power10.S
>
> diff --git a/sysdeps/powerpc/powerpc64/le/power10/strncmp.S b/sysdeps/powerpc/powerpc64/le/power10/strncmp.S
> deleted file mode 100644
> index 10700dd400..0000000000
> --- a/sysdeps/powerpc/powerpc64/le/power10/strncmp.S
> +++ /dev/null
> @@ -1,271 +0,0 @@
> -/* Optimized strncmp implementation for PowerPC64/POWER10.
> - Copyright (C) 2024-2025 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library; if not, see
> - <https://www.gnu.org/licenses/>. */
> -
> -#include <sysdep.h>
> -
> -/* Implements the function
> -
> - int [r3] strncmp (const char *s1 [r3], const char *s2 [r4], size_t [r5] n)
> -
> - The implementation uses unaligned doubleword access to avoid specialized
> - code paths depending of data alignment for first 32 bytes and uses
> - vectorised loops after that. */
> -
> -#ifndef STRNCMP
> -# define STRNCMP strncmp
> -#endif
> -
> -/* TODO: Change this to actual instructions when minimum binutils is upgraded
> - to 2.27. Macros are defined below for these newer instructions in order
> - to maintain compatibility. */
> -
> -#define LXVP(xtp,dq,ra) \
> - .long(((6)<<(32-6)) \
> - | ((((xtp)-32)>>1)<<(32-10)) \
> - | ((1)<<(32-11)) \
> - | ((ra)<<(32-16)) \
> - | dq)
> -
> -#define COMPARE_16(vreg1,vreg2,offset) \
> - lxv vreg1+32,offset(r3); \
> - lxv vreg2+32,offset(r4); \
> - vcmpnezb. v7,vreg1,vreg2; \
> - bne cr6,L(different); \
> - cmpldi cr7,r5,16; \
> - ble cr7,L(ret0); \
> - addi r5,r5,-16;
> -
> -#define COMPARE_32(vreg1,vreg2,offset,label1,label2) \
> - LXVP(vreg1+32,offset,r3); \
> - LXVP(vreg2+32,offset,r4); \
> - vcmpnezb. v7,vreg1+1,vreg2+1; \
> - bne cr6,L(label1); \
> - vcmpnezb. v7,vreg1,vreg2; \
> - bne cr6,L(label2); \
> - cmpldi cr7,r5,32; \
> - ble cr7,L(ret0); \
> - addi r5,r5,-32;
> -
> -#define TAIL_FIRST_16B(vreg1,vreg2) \
> - vctzlsbb r6,v7; \
> - cmpld cr7,r5,r6; \
> - ble cr7,L(ret0); \
> - vextubrx r5,r6,vreg1; \
> - vextubrx r4,r6,vreg2; \
> - subf r3,r4,r5; \
> - blr;
> -
> -#define TAIL_SECOND_16B(vreg1,vreg2) \
> - vctzlsbb r6,v7; \
> - addi r0,r6,16; \
> - cmpld cr7,r5,r0; \
> - ble cr7,L(ret0); \
> - vextubrx r5,r6,vreg1; \
> - vextubrx r4,r6,vreg2; \
> - subf r3,r4,r5; \
> - blr;
> -
> -#define CHECK_N_BYTES(reg1,reg2,len_reg) \
> - sldi r6,len_reg,56; \
> - lxvl 32+v4,reg1,r6; \
> - lxvl 32+v5,reg2,r6; \
> - add reg1,reg1,len_reg; \
> - add reg2,reg2,len_reg; \
> - vcmpnezb v7,v4,v5; \
> - vctzlsbb r6,v7; \
> - cmpld cr7,r6,len_reg; \
> - blt cr7,L(different); \
> - cmpld cr7,r5,len_reg; \
> - ble cr7,L(ret0); \
> - sub r5,r5,len_reg; \
> -
> - /* TODO: change this to .machine power10 when the minimum required
> - binutils allows it. */
> - .machine power9
> -ENTRY_TOCLESS (STRNCMP, 4)
> - /* Check if size is 0. */
> - cmpdi cr0,r5,0
> - beq cr0,L(ret0)
> - andi. r7,r3,4095
> - andi. r8,r4,4095
> - cmpldi cr0,r7,4096-16
> - cmpldi cr1,r8,4096-16
> - bgt cr0,L(crosses)
> - bgt cr1,L(crosses)
> - COMPARE_16(v4,v5,0)
> - addi r3,r3,16
> - addi r4,r4,16
> -
> -L(crosses):
> - andi. r7,r3,15
> - subfic r7,r7,16 /* r7(nalign1) = 16 - (str1 & 15). */
> - andi. r9,r4,15
> - subfic r8,r9,16 /* r8(nalign2) = 16 - (str2 & 15). */
> - cmpld cr7,r7,r8
> - beq cr7,L(same_aligned)
> - blt cr7,L(nalign1_min)
> -
> - /* nalign2 is minimum and s2 pointer is aligned. */
> - CHECK_N_BYTES(r3,r4,r8)
> - /* Are we on the 64B hunk which crosses a page? */
> - andi. r10,r3,63 /* Determine offset into 64B hunk. */
> - andi. r8,r3,15 /* The offset into the 16B hunk. */
> - neg r7,r3
> - andi. r9,r7,15 /* Number of bytes after a 16B cross. */
> - rlwinm. r7,r7,26,0x3F /* ((r4-4096))>>6&63. */
> - beq L(compare_64_pagecross)
> - mtctr r7
> - b L(compare_64B_unaligned)
> -
> - /* nalign1 is minimum and s1 pointer is aligned. */
> -L(nalign1_min):
> - CHECK_N_BYTES(r3,r4,r7)
> - /* Are we on the 64B hunk which crosses a page? */
> - andi. r10,r4,63 /* Determine offset into 64B hunk. */
> - andi. r8,r4,15 /* The offset into the 16B hunk. */
> - neg r7,r4
> - andi. r9,r7,15 /* Number of bytes after a 16B cross. */
> - rlwinm. r7,r7,26,0x3F /* ((r4-4096))>>6&63. */
> - beq L(compare_64_pagecross)
> - mtctr r7
> -
> - .p2align 5
> -L(compare_64B_unaligned):
> - COMPARE_16(v4,v5,0)
> - COMPARE_16(v4,v5,16)
> - COMPARE_16(v4,v5,32)
> - COMPARE_16(v4,v5,48)
> - addi r3,r3,64
> - addi r4,r4,64
> - bdnz L(compare_64B_unaligned)
> -
> - /* Cross the page boundary of s2, carefully. Only for first
> - iteration we have to get the count of 64B blocks to be checked.
> - From second iteration and beyond, loop counter is always 63. */
> -L(compare_64_pagecross):
> - li r11, 63
> - mtctr r11
> - cmpldi r10,16
> - ble L(cross_4)
> - cmpldi r10,32
> - ble L(cross_3)
> - cmpldi r10,48
> - ble L(cross_2)
> -L(cross_1):
> - CHECK_N_BYTES(r3,r4,r9)
> - CHECK_N_BYTES(r3,r4,r8)
> - COMPARE_16(v4,v5,0)
> - COMPARE_16(v4,v5,16)
> - COMPARE_16(v4,v5,32)
> - addi r3,r3,48
> - addi r4,r4,48
> - b L(compare_64B_unaligned)
> -L(cross_2):
> - COMPARE_16(v4,v5,0)
> - addi r3,r3,16
> - addi r4,r4,16
> - CHECK_N_BYTES(r3,r4,r9)
> - CHECK_N_BYTES(r3,r4,r8)
> - COMPARE_16(v4,v5,0)
> - COMPARE_16(v4,v5,16)
> - addi r3,r3,32
> - addi r4,r4,32
> - b L(compare_64B_unaligned)
> -L(cross_3):
> - COMPARE_16(v4,v5,0)
> - COMPARE_16(v4,v5,16)
> - addi r3,r3,32
> - addi r4,r4,32
> - CHECK_N_BYTES(r3,r4,r9)
> - CHECK_N_BYTES(r3,r4,r8)
> - COMPARE_16(v4,v5,0)
> - addi r3,r3,16
> - addi r4,r4,16
> - b L(compare_64B_unaligned)
> -L(cross_4):
> - COMPARE_16(v4,v5,0)
> - COMPARE_16(v4,v5,16)
> - COMPARE_16(v4,v5,32)
> - addi r3,r3,48
> - addi r4,r4,48
> - CHECK_N_BYTES(r3,r4,r9)
> - CHECK_N_BYTES(r3,r4,r8)
> - b L(compare_64B_unaligned)
> -
> -L(same_aligned):
> - CHECK_N_BYTES(r3,r4,r7)
> - /* Align s1 to 32B and adjust s2 address.
> - Use lxvp only if both s1 and s2 are 32B aligned. */
> - COMPARE_16(v4,v5,0)
> - COMPARE_16(v4,v5,16)
> - COMPARE_16(v4,v5,32)
> - COMPARE_16(v4,v5,48)
> - addi r3,r3,64
> - addi r4,r4,64
> - COMPARE_16(v4,v5,0)
> - COMPARE_16(v4,v5,16)
> - addi r5,r5,32
> -
> - clrldi r6,r3,59
> - subfic r7,r6,32
> - add r3,r3,r7
> - add r4,r4,r7
> - subf r5,r7,r5
> - andi. r7,r4,0x1F
> - beq cr0,L(32B_aligned_loop)
> -
> - .p2align 5
> -L(16B_aligned_loop):
> - COMPARE_16(v4,v5,0)
> - COMPARE_16(v4,v5,16)
> - COMPARE_16(v4,v5,32)
> - COMPARE_16(v4,v5,48)
> - addi r3,r3,64
> - addi r4,r4,64
> - b L(16B_aligned_loop)
> -
> - /* Calculate and return the difference. */
> -L(different):
> - TAIL_FIRST_16B(v4,v5)
> -
> - .p2align 5
> -L(32B_aligned_loop):
> - COMPARE_32(v14,v16,0,tail1,tail2)
> - COMPARE_32(v18,v20,32,tail3,tail4)
> - COMPARE_32(v22,v24,64,tail5,tail6)
> - COMPARE_32(v26,v28,96,tail7,tail8)
> - addi r3,r3,128
> - addi r4,r4,128
> - b L(32B_aligned_loop)
> -
> -L(tail1): TAIL_FIRST_16B(v15,v17)
> -L(tail2): TAIL_SECOND_16B(v14,v16)
> -L(tail3): TAIL_FIRST_16B(v19,v21)
> -L(tail4): TAIL_SECOND_16B(v18,v20)
> -L(tail5): TAIL_FIRST_16B(v23,v25)
> -L(tail6): TAIL_SECOND_16B(v22,v24)
> -L(tail7): TAIL_FIRST_16B(v27,v29)
> -L(tail8): TAIL_SECOND_16B(v26,v28)
> -
> - .p2align 5
> -L(ret0):
> - li r3,0
> - blr
> -
> -END(STRNCMP)
> -libc_hidden_builtin_def(strncmp)
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
> index 624439d8c3..79fcc6597c 100644
> --- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
> +++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
> @@ -33,7 +33,7 @@ ifneq (,$(filter %le,$(config-machine)))
> sysdep_routines += memchr-power10 memcmp-power10 memcpy-power10 \
> memmove-power10 memset-power10 rawmemchr-power9 \
> rawmemchr-power10 strcmp-power9 strcmp-power10 \
> - strncmp-power9 strncmp-power10 strcpy-power9 strcat-power10 \
> + strncmp-power9 strcpy-power9 strcat-power10 \
> stpcpy-power9 strlen-power9 strncpy-power9 stpncpy-power9 \
> strlen-power10
> endif
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> index f3acd38b22..1a3439cdc7 100644
> --- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> +++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> @@ -164,9 +164,6 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> /* Support sysdeps/powerpc/powerpc64/multiarch/strncmp.c. */
> IFUNC_IMPL (i, name, strncmp,
> #ifdef __LITTLE_ENDIAN__
> - IFUNC_IMPL_ADD (array, i, strncmp, hwcap2 & PPC_FEATURE2_ARCH_3_1
> - && hwcap & PPC_FEATURE_HAS_VSX,
> - __strncmp_power10)
> IFUNC_IMPL_ADD (array, i, strncmp, hwcap2 & PPC_FEATURE2_ARCH_3_00
> && hwcap & PPC_FEATURE_HAS_ALTIVEC,
> __strncmp_power9)
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/strncmp-power10.S b/sysdeps/powerpc/powerpc64/multiarch/strncmp-power10.S
> deleted file mode 100644
> index 43879085e2..0000000000
> --- a/sysdeps/powerpc/powerpc64/multiarch/strncmp-power10.S
> +++ /dev/null
> @@ -1,25 +0,0 @@
> -/* Copyright (C) 2024-2025 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library; if not, see
> - <https://www.gnu.org/licenses/>. */
> -
> -#if defined __LITTLE_ENDIAN__ && IS_IN (libc)
> -#define STRNCMP __strncmp_power10
> -
> -#undef libc_hidden_builtin_def
> -#define libc_hidden_builtin_def(name)
> -
> -#include <sysdeps/powerpc/powerpc64/le/power10/strncmp.S>
> -#endif
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/strncmp.c b/sysdeps/powerpc/powerpc64/multiarch/strncmp.c
> index 0a664a620d..4cfe27fa45 100644
> --- a/sysdeps/powerpc/powerpc64/multiarch/strncmp.c
> +++ b/sysdeps/powerpc/powerpc64/multiarch/strncmp.c
> @@ -29,7 +29,6 @@ extern __typeof (strncmp) __strncmp_ppc attribute_hidden;
> extern __typeof (strncmp) __strncmp_power8 attribute_hidden;
> # ifdef __LITTLE_ENDIAN__
> extern __typeof (strncmp) __strncmp_power9 attribute_hidden;
> -extern __typeof (strncmp) __strncmp_power10 attribute_hidden;
> # endif
> # undef strncmp
>
> @@ -37,9 +36,6 @@ extern __typeof (strncmp) __strncmp_power10 attribute_hidden;
> ifunc symbol properly. */
> libc_ifunc_redirected (__redirect_strncmp, strncmp,
> # ifdef __LITTLE_ENDIAN__
> - (hwcap2 & PPC_FEATURE2_ARCH_3_1
> - && hwcap & PPC_FEATURE_HAS_VSX)
> - ? __strncmp_power10 :
> (hwcap2 & PPC_FEATURE2_ARCH_3_00
> && hwcap & PPC_FEATURE_HAS_ALTIVEC)
> ? __strncmp_power9 :
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