| Message ID | 20190215141132.24404-1-adhemerval.zanella@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] powerpc: Remove rt_sigreturn usage on context function | expand |
If no one opposes I will commit this shortly. On 15/02/2019 12:11, Adhemerval Zanella wrote: > 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 > --- > .../powerpc/powerpc32/setcontext-common.S | 22 ------- > .../powerpc/powerpc32/swapcontext-common.S | 23 -------- > .../sysv/linux/powerpc/powerpc64/setcontext.S | 59 ------------------- > .../linux/powerpc/powerpc64/swapcontext.S | 58 ------------------ > 4 files changed, 162 deletions(-) > > diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S b/sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S > index 68c6321a9d..47235dd0cb 100644 > --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S > +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S > @@ -47,21 +47,6 @@ ENTRY(__CONTEXT_FUNC_NAME) > cfi_offset(r31,-4) > 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 */ > li r5,0 > addi r4,r3,_UC_SIGMASK > @@ -296,11 +281,4 @@ ENTRY(__CONTEXT_FUNC_NAME) > mtlr r0 > blr > > - > -4: /* L(do_sigret): */ > - addi r1,r3,-0xd0 > - li r0,SYS_ify(rt_sigreturn) > - sc > - /* NOTREACHED */ > - > END (__CONTEXT_FUNC_NAME) > diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S b/sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S > index 0ef0ad7e35..e0fd249615 100644 > --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S > +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S > @@ -280,23 +280,6 @@ ENTRY(__CONTEXT_FUNC_NAME) > cmpwi r3,0 > 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_VRS > > @@ -520,10 +503,4 @@ ENTRY(__CONTEXT_FUNC_NAME) > mtlr r0 > blr > > -4:/*L(do_sigret):*/ > - addi r1,r4,-0xd0 > - li r0,SYS_ify(rt_sigreturn) > - sc > - /* NOTREACHED */ > - > END(__CONTEXT_FUNC_NAME) > diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S > index 4e3ab6647a..d311a22c58 100644 > --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S > +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S > @@ -46,20 +46,6 @@ ENTRY(__novec_setcontext) > cfi_adjust_cfa_offset (128) > 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 > addi r4,r3,UCONTEXT_SIGMASK > li r3,SIG_SETMASK > @@ -200,22 +186,6 @@ L(nv_error_exit): > mtlr r0 > ld r31,-8(r1) > 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) > > compat_symbol (libc, __novec_setcontext, setcontext, GLIBC_2_3) > @@ -235,20 +205,6 @@ ENTRY(__setcontext) > cfi_adjust_cfa_offset (128) > 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 > addi r4,r3,UCONTEXT_SIGMASK > li r3,SIG_SETMASK > @@ -493,21 +449,6 @@ L(error_exit): > ld r31,-8(r1) > 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) > > versioned_symbol (libc, __setcontext, setcontext, GLIBC_2_3_4) > diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S > index af5b108e8c..6d07b1c36b 100644 > --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S > +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S > @@ -149,20 +149,6 @@ ENTRY(__novec_swapcontext) > cmpdi r3,0 > 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) > # ifdef SHARED > /* Load _rtld-global._dl_hwcap. */ > @@ -288,21 +274,6 @@ L(nv_error_exit): > ld r31,-8(r1) > 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) > > compat_symbol (libc, __novec_swapcontext, swapcontext, GLIBC_2_3) > @@ -535,20 +506,6 @@ L(has_no_vec): > cmpdi r3,0 > 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 r10,(SIGCONTEXT_V_REGS_PTR)(r31) > # ifdef SHARED > @@ -777,21 +734,6 @@ L(error_exit): > ld r31,-8(r1) > 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) > > versioned_symbol (libc, __swapcontext, swapcontext, GLIBC_2_3_4) >
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S b/sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S index 68c6321a9d..47235dd0cb 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/setcontext-common.S @@ -47,21 +47,6 @@ ENTRY(__CONTEXT_FUNC_NAME) cfi_offset(r31,-4) 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 */ li r5,0 addi r4,r3,_UC_SIGMASK @@ -296,11 +281,4 @@ ENTRY(__CONTEXT_FUNC_NAME) mtlr r0 blr - -4: /* L(do_sigret): */ - addi r1,r3,-0xd0 - li r0,SYS_ify(rt_sigreturn) - sc - /* NOTREACHED */ - END (__CONTEXT_FUNC_NAME) diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S b/sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S index 0ef0ad7e35..e0fd249615 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/swapcontext-common.S @@ -280,23 +280,6 @@ ENTRY(__CONTEXT_FUNC_NAME) cmpwi r3,0 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_VRS @@ -520,10 +503,4 @@ ENTRY(__CONTEXT_FUNC_NAME) mtlr r0 blr -4:/*L(do_sigret):*/ - addi r1,r4,-0xd0 - li r0,SYS_ify(rt_sigreturn) - sc - /* NOTREACHED */ - END(__CONTEXT_FUNC_NAME) diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S index 4e3ab6647a..d311a22c58 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S @@ -46,20 +46,6 @@ ENTRY(__novec_setcontext) cfi_adjust_cfa_offset (128) 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 addi r4,r3,UCONTEXT_SIGMASK li r3,SIG_SETMASK @@ -200,22 +186,6 @@ L(nv_error_exit): mtlr r0 ld r31,-8(r1) 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) compat_symbol (libc, __novec_setcontext, setcontext, GLIBC_2_3) @@ -235,20 +205,6 @@ ENTRY(__setcontext) cfi_adjust_cfa_offset (128) 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 addi r4,r3,UCONTEXT_SIGMASK li r3,SIG_SETMASK @@ -493,21 +449,6 @@ L(error_exit): ld r31,-8(r1) 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) versioned_symbol (libc, __setcontext, setcontext, GLIBC_2_3_4) diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S index af5b108e8c..6d07b1c36b 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S @@ -149,20 +149,6 @@ ENTRY(__novec_swapcontext) cmpdi r3,0 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) # ifdef SHARED /* Load _rtld-global._dl_hwcap. */ @@ -288,21 +274,6 @@ L(nv_error_exit): ld r31,-8(r1) 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) compat_symbol (libc, __novec_swapcontext, swapcontext, GLIBC_2_3) @@ -535,20 +506,6 @@ L(has_no_vec): cmpdi r3,0 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 r10,(SIGCONTEXT_V_REGS_PTR)(r31) # ifdef SHARED @@ -777,21 +734,6 @@ L(error_exit): ld r31,-8(r1) 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) versioned_symbol (libc, __swapcontext, swapcontext, GLIBC_2_3_4)