lib/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2025-07-30 22:43:12 +03:00
Code Activity

powerpc: Remove rt_sigreturn usage on context function

Browse Source 
As described in a recent glibc thread [1], the rt_sigreturn syscall
on setcontext and swapcontext is not used on default use and its
intention is no really supported since neither setcontext nor
swapcontext are async-signal-safe.

Checked on powerpc64-linux-gnu and powerpc-linux-gnu.

	* sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S:
	Remove rt_sigreturn call.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S:
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S: Likewie.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S: Likewise.

[1] https://sourceware.org/ml/libc-alpha/2019-02/msg00367.html
This commit is contained in:
Adhemerval Zanella
2019-02-15 11:55:16 -02:00
parent 0e16969129
commit ffe8a9a831
5 changed files with 7 additions and 162 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
ChangeLog
View File

@ -1,5 +1,12 @@
2019-04-17 Adhemerval Zanella <adhemerval.zanella@linaro.org> 2019-04-17 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S:
Remove rt_sigreturn call.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S: Likewie.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S: Likewise.
* support/Makefile (libsupport-routines): Add support_subprocess, * support/Makefile (libsupport-routines): Add support_subprocess,
xposix_spawn, xposix_spawn_file_actions_addclose, and xposix_spawn, xposix_spawn_file_actions_addclose, and
xposix_spawn_file_actions_adddup2. xposix_spawn_file_actions_adddup2.

22
sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S
View File

@ -47,21 +47,6 @@ ENTRY(__CONTEXT_FUNC_NAME)
cfi_offset(r31,-4) cfi_offset(r31,-4)
lwz r31,_UC_REGS_PTR(r3) lwz r31,_UC_REGS_PTR(r3)
/*
* If this ucontext refers to the point where we were interrupted
* by a signal, we have to use the rt_sigreturn system call to
* return to the context so we get both LR and CTR restored.
*
* Otherwise, the context we are restoring is either just after
* a procedure call (getcontext/swapcontext) or at the beginning
* of a procedure call (makecontext), so we don't need to restore
* r0, xer, ctr. We don't restore r2 since it will be used as
* the TLS pointer.
*/
lwz r0,_UC_GREGS+(PT_MSR*4)(r31)
cmpwi r0,0
bne 4f /* L(do_sigret) */
/* Restore the signal mask */ /* Restore the signal mask */
li r5,0 li r5,0
addi r4,r3,_UC_SIGMASK addi r4,r3,_UC_SIGMASK
@ -296,11 +281,4 @@ ENTRY(__CONTEXT_FUNC_NAME)
mtlr r0 mtlr r0
blr blr
4: /* L(do_sigret): */
addi r1,r3,-0xd0
li r0,SYS_ify(rt_sigreturn)
sc
/* NOTREACHED */
END (__CONTEXT_FUNC_NAME) END (__CONTEXT_FUNC_NAME)

23
sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S
View File

@ -280,23 +280,6 @@ ENTRY(__CONTEXT_FUNC_NAME)
cmpwi r3,0 cmpwi r3,0
bne 3f /* L(error_exit) */ bne 3f /* L(error_exit) */
/*
* If the new ucontext refers to the point where we were interrupted
* by a signal, we have to use the rt_sigreturn system call to
* return to the context so we get both LR and CTR restored.
*
* Otherwise, the context we are restoring is either just after
* a procedure call (getcontext/swapcontext) or at the beginning
* of a procedure call (makecontext), so we don't need to restore
* r0, xer, ctr. We don't restore r2 since it will be used as
* the TLS pointer.
*/
lwz r4,_FRAME_PARM_SAVE2(r1)
lwz r31,_UC_REGS_PTR(r4)
lwz r0,_UC_GREGS+(PT_MSR*4)(r31)
cmpwi r0,0
bne 4f /* L(do_sigret) */
#ifdef __CONTEXT_ENABLE_FPRS #ifdef __CONTEXT_ENABLE_FPRS
# ifdef __CONTEXT_ENABLE_VRS # ifdef __CONTEXT_ENABLE_VRS
@ -520,10 +503,4 @@ ENTRY(__CONTEXT_FUNC_NAME)
mtlr r0 mtlr r0
blr blr
4:/*L(do_sigret):*/
addi r1,r4,-0xd0
li r0,SYS_ify(rt_sigreturn)
sc
/* NOTREACHED */
END(__CONTEXT_FUNC_NAME) END(__CONTEXT_FUNC_NAME)

59
sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S
View File

@ -46,20 +46,6 @@ ENTRY(__novec_setcontext)
cfi_adjust_cfa_offset (128) cfi_adjust_cfa_offset (128)
mr r31,r3 mr r31,r3
/*
* If this ucontext refers to the point where we were interrupted
* by a signal, we have to use the rt_sigreturn system call to
* return to the context so we get both LR and CTR restored.
*
* Otherwise, the context we are restoring is either just after
* a procedure call (getcontext/swapcontext) or at the beginning
* of a procedure call (makecontext), so we don't need to restore
* msr and ctr. We don't restore r13 since it will be used as
* the TLS pointer. */
ld r0,(SIGCONTEXT_GP_REGS+(PT_MSR*8))(r31)
cmpdi r0,0
bne L(nv_do_sigret)
li r5,0 li r5,0
addi r4,r3,UCONTEXT_SIGMASK addi r4,r3,UCONTEXT_SIGMASK
li r3,SIG_SETMASK li r3,SIG_SETMASK
@ -200,22 +186,6 @@ L(nv_error_exit):
mtlr r0 mtlr r0
ld r31,-8(r1) ld r31,-8(r1)
blr blr
/* At this point we assume that the ucontext was created by a
rt_signal and we should use rt_sigreturn to restore the original
state. As of the 2.4.21 kernel the ucontext is the first thing
(offset 0) in the rt_signal frame and rt_sigreturn expects the
ucontext address in R1. Normally the rt-signal trampoline handles
this by popping dummy frame before the rt_signal syscall. In our
case the stack may not be in its original (signal handler return with
R1 pointing at the dummy frame) state. We do have the ucontext
address in R3, so simply copy R3 to R1 before the syscall. */
L(nv_do_sigret):
mr r1,r3,
li r0,SYS_ify(rt_sigreturn)
sc
/* No return. */
PSEUDO_END(__novec_setcontext) PSEUDO_END(__novec_setcontext)
compat_symbol (libc, __novec_setcontext, setcontext, GLIBC_2_3) compat_symbol (libc, __novec_setcontext, setcontext, GLIBC_2_3)
@ -235,20 +205,6 @@ ENTRY(__setcontext)
cfi_adjust_cfa_offset (128) cfi_adjust_cfa_offset (128)
mr r31,r3 mr r31,r3
/*
* If this ucontext refers to the point where we were interrupted
* by a signal, we have to use the rt_sigreturn system call to
* return to the context so we get both LR and CTR restored.
*
* Otherwise, the context we are restoring is either just after
* a procedure call (getcontext/swapcontext) or at the beginning
* of a procedure call (makecontext), so we don't need to restore
* msr and ctr. We don't restore r13 since it will be used as
* the TLS pointer. */
ld r0,(SIGCONTEXT_GP_REGS+(PT_MSR*8))(r31)
cmpdi r0,0
bne L(do_sigret)
li r5,0 li r5,0
addi r4,r3,UCONTEXT_SIGMASK addi r4,r3,UCONTEXT_SIGMASK
li r3,SIG_SETMASK li r3,SIG_SETMASK
@ -493,21 +449,6 @@ L(error_exit):
ld r31,-8(r1) ld r31,-8(r1)
blr blr
/* At this point we assume that the ucontext was created by a
rt_signal and we should use rt_sigreturn to restore the original
state. As of the 2.4.21 kernel the ucontext is the first thing
(offset 0) in the rt_signal frame and rt_sigreturn expects the
ucontext address in R1. Normally the rt-signal trampoline handles
this by popping dummy frame before the rt_signal syscall. In our
case the stack may not be in its original (signal handler return with
R1 pointing at the dummy frame) state. We do have the ucontext
address in R3, so simply copy R3 to R1 before the syscall. */
L(do_sigret):
mr r1,r3,
li r0,SYS_ify(rt_sigreturn)
sc
/* No return. */
PSEUDO_END(__setcontext) PSEUDO_END(__setcontext)
versioned_symbol (libc, __setcontext, setcontext, GLIBC_2_3_4) versioned_symbol (libc, __setcontext, setcontext, GLIBC_2_3_4)

58
sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S
View File

@ -149,20 +149,6 @@ ENTRY(__novec_swapcontext)
cmpdi r3,0 cmpdi r3,0
bne L(nv_error_exit) bne L(nv_error_exit)
/*
* If this new ucontext refers to the point where we were interrupted
* by a signal, we have to use the rt_sigreturn system call to
* return to the context so we get both LR and CTR restored.
*
* Otherwise, the context we are restoring is either just after
* a procedure call (getcontext/swapcontext) or at the beginning
* of a procedure call (makecontext), so we don't need to restore
* msr and ctr. We don't restore r13 since it will be used as
* the TLS pointer. */
ld r0,(SIGCONTEXT_GP_REGS+(PT_MSR*8))(r31)
cmpdi r0,0
bne L(nv_do_sigret)
ld r8,.LC__dl_hwcap@toc(r2) ld r8,.LC__dl_hwcap@toc(r2)
# ifdef SHARED # ifdef SHARED
/* Load _rtld-global._dl_hwcap. */ /* Load _rtld-global._dl_hwcap. */
@ -288,21 +274,6 @@ L(nv_error_exit):
ld r31,-8(r1) ld r31,-8(r1)
blr blr
/* At this point we assume that the ucontext was created by a
rt_signal and we should use rt_sigreturn to restore the original
state. As of the 2.4.21 kernel the ucontext is the first thing
(offset 0) in the rt_signal frame and rt_sigreturn expects the
ucontext address in R1. Normally the rt-signal trampoline handles
this by popping dummy frame before the rt_signal syscall. In our
case the stack may not be in its original (signal handler return with
R1 pointing at the dummy frame) state. We do have the ucontext
address in R3, so simply copy R3 to R1 before the syscall. */
L(nv_do_sigret):
mr r1,r3,
li r0,SYS_ify(rt_sigreturn)
sc
/* No return. */
PSEUDO_END(__novec_swapcontext) PSEUDO_END(__novec_swapcontext)
compat_symbol (libc, __novec_swapcontext, swapcontext, GLIBC_2_3) compat_symbol (libc, __novec_swapcontext, swapcontext, GLIBC_2_3)
@ -535,20 +506,6 @@ L(has_no_vec):
cmpdi r3,0 cmpdi r3,0
bne L(error_exit) bne L(error_exit)
/*
* If this new ucontext refers to the point where we were interrupted
* by a signal, we have to use the rt_sigreturn system call to
* return to the context so we get both LR and CTR restored.
*
* Otherwise, the context we are restoring is either just after
* a procedure call (getcontext/swapcontext) or at the beginning
* of a procedure call (makecontext), so we don't need to restore
* msr and ctr. We don't restore r13 since it will be used as
* the TLS pointer. */
ld r0,(SIGCONTEXT_GP_REGS+(PT_MSR*8))(r31)
cmpdi r0,0
bne L(do_sigret)
ld r8,.LC__dl_hwcap@toc(r2) ld r8,.LC__dl_hwcap@toc(r2)
ld r10,(SIGCONTEXT_V_REGS_PTR)(r31) ld r10,(SIGCONTEXT_V_REGS_PTR)(r31)
# ifdef SHARED # ifdef SHARED
@ -777,21 +734,6 @@ L(error_exit):
ld r31,-8(r1) ld r31,-8(r1)
blr blr
/* At this point we assume that the ucontext was created by a
rt_signal and we should use rt_sigreturn to restore the original
state. As of the 2.4.21 kernel the ucontext is the first thing
(offset 0) in the rt_signal frame and rt_sigreturn expects the
ucontext address in R1. Normally the rt-signal trampoline handles
this by popping dummy frame before the rt_signal syscall. In our
case the stack may not be in its original (signal handler return with
R1 pointing at the dummy frame) state. We do have the ucontext
address in R3, so simply copy R3 to R1 before the syscall. */
L(do_sigret):
mr r1,r3,
li r0,SYS_ify(rt_sigreturn)
sc
/* No return. */
PSEUDO_END(__swapcontext) PSEUDO_END(__swapcontext)
versioned_symbol (libc, __swapcontext, swapcontext, GLIBC_2_3_4) versioned_symbol (libc, __swapcontext, swapcontext, GLIBC_2_3_4)