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[PATCH 2/2] mips: Remove rt_sigreturn usage on context function

From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
To: libc-alpha at sourceware dot org
Date: Fri, 15 Feb 2019 12:11:32 -0200
Subject: [PATCH 2/2] mips: Remove rt_sigreturn usage on context function
References: <20190215141132.24404-1-adhemerval.zanella@linaro.org>

Similar to powerpc, mips also issues rt_sigreturn for setcontext
case the v0 value saved is not the one set by setcontext or
makecontext. As for powerpc, it is intention is no really supported
since setcontext is not async-signal-safe.

Checked the context tests on mips64-linux-gnu and mips-linux-gnu.

	* sysdeps/unix/sysv/linux/mips/getcontext.S (__getcontext): Remove
	the magic flag store.
	* sysdeps/unix/sysv/linux/mips/makecontext.S (__makecontext):
	Likewise.
	* sysdeps/unix/sysv/linux/mips/swapcontext.S (__swapcontext):
	Likewise.
	* sysdeps/unix/sysv/linux/mips/setcontext.S (__setcontext):
	Remove rt_sigreturn call.
---
 sysdeps/unix/sysv/linux/mips/getcontext.S  |  5 ---
 sysdeps/unix/sysv/linux/mips/makecontext.S |  5 ---
 sysdeps/unix/sysv/linux/mips/setcontext.S  | 38 ----------------------
 sysdeps/unix/sysv/linux/mips/swapcontext.S |  5 ---
 4 files changed, 53 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/mips/getcontext.S b/sysdeps/unix/sysv/linux/mips/getcontext.S
index 4f7f89ee9a..015bd5bff6 100644
--- a/sysdeps/unix/sysv/linux/mips/getcontext.S
+++ b/sysdeps/unix/sysv/linux/mips/getcontext.S
@@ -78,11 +78,6 @@ NESTED (__getcontext, FRAMESZ, ra)
 	.set	at
 #endif
 
-	/* Store a magic flag.	*/
-	li	v1, 1
-	/* zero */
-	REG_S	v1, (MCONTEXT_GREGOFF + 0 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
-
 	REG_S	s0, (MCONTEXT_GREGOFF + 16 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
 	REG_S	s1, (MCONTEXT_GREGOFF + 17 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
 	REG_S	s2, (MCONTEXT_GREGOFF + 18 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
diff --git a/sysdeps/unix/sysv/linux/mips/makecontext.S b/sysdeps/unix/sysv/linux/mips/makecontext.S
index 4439fec3ff..3f40f7c9f2 100644
--- a/sysdeps/unix/sysv/linux/mips/makecontext.S
+++ b/sysdeps/unix/sysv/linux/mips/makecontext.S
@@ -93,11 +93,6 @@ NESTED (__makecontext, FRAMESZ, ra)
 	REG_S	a7, A7OFF(sp)
 #endif
 
-	/* Store a magic flag.  */
-	li	v1, 1
-	/* zero */
-	REG_S	v1, (MCONTEXT_GREGOFF + 0 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
-
 	/* Set up the stack.  */
 	PTR_L	t0, STACK_SP(a0)
 	PTR_L	t2, STACK_SIZE(a0)
diff --git a/sysdeps/unix/sysv/linux/mips/setcontext.S b/sysdeps/unix/sysv/linux/mips/setcontext.S
index b6553bdb5e..98afe6cbac 100644
--- a/sysdeps/unix/sysv/linux/mips/setcontext.S
+++ b/sysdeps/unix/sysv/linux/mips/setcontext.S
@@ -77,12 +77,6 @@ NESTED (__setcontext, FRAMESZ, ra)
 	.set	at
 #endif
 
-	/* Check for the magic flag.  */
-	li	v0, 1
-	/* zero */
-	REG_L	v1, (MCONTEXT_GREGOFF + 0 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
-	bne	v0, v1, 98f
-
 	REG_S	a0, A0OFF(sp)
 
 /* rt_sigprocmask (SIG_SETMASK, &ucp->uc_sigmask, NULL, _NSIG8) */
@@ -154,38 +148,6 @@ NESTED (__setcontext, FRAMESZ, ra)
 	move	v0, zero
 	jr	t9
 
-98:
-	/* This is a context obtained from a signal handler.
-	   Perform a full restore by pushing the context
-	   passed onto a simulated signal frame on the stack
-	   and call the signal return syscall as if a signal
-	   handler exited normally.  */
-	PTR_ADDIU sp, -((RT_SIGFRAME_SIZE + ALSZ) & ALMASK)
-	cfi_adjust_cfa_offset ((RT_SIGFRAME_SIZE + ALSZ) & ALMASK)
-
-	/* Only ucontext is referred to from rt_sigreturn,
-	   copy it.  */
-	PTR_ADDIU t1, sp, RT_SIGFRAME_UCONTEXT
-	li	t3, ((UCONTEXT_SIZE + SZREG - 1) / SZREG) - 1
-0:
-	REG_L	t2, (a0)
-	PTR_ADDIU a0, SZREG
-	REG_S	t2, (t1)
-	PTR_ADDIU t1, SZREG
-	.set	noreorder
-	bgtz	t3, 0b
-	 addiu	t3, -1
-	.set	reorder
-
-/* rt_sigreturn () -- no arguments, sp points to struct rt_sigframe.  */
-	li	v0, SYS_ify (rt_sigreturn)
-	syscall
-
-	/* Restore the stack and fall through to the error
-	   path.  Successful rt_sigreturn never returns to
-	   its calling place.  */
-	PTR_ADDIU sp, ((RT_SIGFRAME_SIZE + ALSZ) & ALMASK)
-	cfi_adjust_cfa_offset (-((RT_SIGFRAME_SIZE + ALSZ) & ALMASK))
 99:
 #ifdef __PIC__
 	PTR_LA	t9, JUMPTARGET (__syscall_error)
diff --git a/sysdeps/unix/sysv/linux/mips/swapcontext.S b/sysdeps/unix/sysv/linux/mips/swapcontext.S
index 9c68961345..6612e757cd 100644
--- a/sysdeps/unix/sysv/linux/mips/swapcontext.S
+++ b/sysdeps/unix/sysv/linux/mips/swapcontext.S
@@ -87,11 +87,6 @@ NESTED (__swapcontext, FRAMESZ, ra)
 	.set	at
 #endif
 
-	/* Store a magic flag.	*/
-	li	v1, 1
-	/* zero */
-	REG_S	v1, (MCONTEXT_GREGOFF + 0 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
-
 	REG_S	s0, (MCONTEXT_GREGOFF + 16 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
 	REG_S	s1, (MCONTEXT_GREGOFF + 17 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
 	REG_S	s2, (MCONTEXT_GREGOFF + 18 * MCONTEXT_GREGSZ + MCONTEXT_GREGS)(a0)
-- 
2.17.1

References:
- [PATCH 1/2] powerpc: Remove rt_sigreturn usage on context function
  - From: Adhemerval Zanella

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