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

2 files changed, 0 insertions, 117 deletions

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)