From ffe8a9a8318e1db225b22da8bc067408494bac5c Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Fri, 15 Feb 2019 11:55:16 -0200 Subject: powerpc: Remove rt_sigreturn usage on context function 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 --- .../linux/powerpc/powerpc32/setcontext-common.S | 22 -------- .../linux/powerpc/powerpc32/swapcontext-common.S | 23 --------- .../unix/sysv/linux/powerpc/powerpc64/setcontext.S | 59 ---------------------- .../sysv/linux/powerpc/powerpc64/swapcontext.S | 58 --------------------- 4 files changed, 162 deletions(-) (limited to 'sysdeps/unix/sysv/linux') 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) -- cgit 1.4.1