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powerpc64: Obviate the need for ROP protection in clone/clone3

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Save lr in a non-volatile register before scv in clone/clone3.
For clone, the non-volatile register was unused and already
saved/restored.  Remove the dead code from clone.

Signed-off-by: Sachin Monga <smonga@linux.ibm.com>
Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
This commit is contained in:
Sachin Monga 2024-10-30 16:43:37 -04:00 committed by Peter Bergner
parent e5ea9aef54
commit 383e4f53cb
2 changed files with 21 additions and 21 deletions
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7
sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
View File

@ -56,7 +56,6 @@ ENTRY (__clone)
/* Save fn, args, stack across syscall. */ /* Save fn, args, stack across syscall. */
mr r30,r3 /* Function in r30. */ mr r30,r3 /* Function in r30. */
mr r29,r5 /* Flags in r29. */
mr r31,r6 /* Argument in r31. */ mr r31,r6 /* Argument in r31. */
/* 'flags' argument is first parameter to clone syscall. /* 'flags' argument is first parameter to clone syscall.
@ -77,14 +76,12 @@ ENTRY (__clone)
CHECK_SCV_SUPPORT r28 0f CHECK_SCV_SUPPORT r28 0f
/* This is equivalent to DO_CALL_SCV, but we cannot use the macro here /* This is equivalent to DO_CALL_SCV, but we cannot use the macro here
because it uses CFI directives and we just called cfi_endproc. */ because it uses CFI directives and we just called cfi_endproc. */
mflr r9 mflr r29
std r9,FRAME_LR_SAVE(r1)
.machine "push" .machine "push"
.machine "power9" .machine "power9"
scv 0 scv 0
.machine "pop" .machine "pop"
ld r9,FRAME_LR_SAVE(r1) mtlr r29
mtlr r9
/* Check for child process. */ /* Check for child process. */
/* When using scv, error is indicated by negative r3. */ /* When using scv, error is indicated by negative r3. */

35
sysdeps/unix/sysv/linux/powerpc/powerpc64/clone3.S
View File

@ -39,14 +39,12 @@
because it uses CFI directives and we just called cfi_endproc. */ because it uses CFI directives and we just called cfi_endproc. */
# define DO_CLONE3_SVC_CALL(jumpfalse) \ # define DO_CLONE3_SVC_CALL(jumpfalse) \
CHECK_SCV_SUPPORT r28 jumpfalse; \ CHECK_SCV_SUPPORT r28 jumpfalse; \
mflr r9; \ mflr r31; \
std r9, FRAME_LR_SAVE(r1); \
.machine "push"; \ .machine "push"; \
.machine "power9"; \ .machine "power9"; \
scv 0; \ scv 0; \
.machine "pop"; \ .machine "pop"; \
ld r9, FRAME_LR_SAVE(r1); \ mtlr r31; \
mtlr r9; \
/* With scv an, an error is a value -4095 <= x < 0. */ \ /* With scv an, an error is a value -4095 <= x < 0. */ \
cmpdi cr1, r3, 0; \ cmpdi cr1, r3, 0; \
b 1f; b 1f;
@ -66,13 +64,15 @@ ENTRY(__clone3)
/* Save some regs in the "red zone". */ /* Save some regs in the "red zone". */
#ifdef USE_PPC_SCV #ifdef USE_PPC_SCV
std r28, -24(r1) std r28, -32(r1)
cfi_offset (r28, -24) cfi_offset (r28, -32)
#endif #endif
std r29, -16(r1) std r29, -24(r1)
std r30, -8(r1) std r30, -16(r1)
cfi_offset (r29, -16) std r31, -8(r1)
cfi_offset (r30, -8) cfi_offset (r29, -24)
cfi_offset (r30, -16)
cfi_offset (r31, -8)
/* Save func and arg across syscall. */ /* Save func and arg across syscall. */
mr r30, r5 /* Function in r30. */ mr r30, r5 /* Function in r30. */
@ -132,16 +132,19 @@ L(parent):
/* Parent. Restore registers & return. */ /* Parent. Restore registers & return. */
#ifdef USE_PPC_SCV #ifdef USE_PPC_SCV
cfi_offset (r28, -24) cfi_offset (r28, -32)
ld r28, -24(r1) ld r28, -32(r1)
cfi_restore (r28) cfi_restore (r28)
#endif #endif
cfi_offset (r29,-16) cfi_offset (r29,-24)
cfi_offset (r30,-8) cfi_offset (r30,-16)
ld r29, -16(r1) cfi_offset (r31,-8)
ld r30, -8(r1) ld r29, -24(r1)
ld r30, -16(r1)
ld r31, -8(r1)
cfi_restore (r29) cfi_restore (r29)
cfi_restore (r30) cfi_restore (r30)
cfi_restore (r31)
#ifdef USE_PPC_SCV #ifdef USE_PPC_SCV
beq cr1, 0f beq cr1, 0f