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Re: [PATCH][SH] SH CFI directives patch, revised


Hi!

On Mon, 28 May 2012 08:23:34 +0900, Kaz Kojima <kkojima@rr.iij4u.or.jp> wrote:
> Thomas Schwinge <thomas@codesourcery.com> wrote:
> >> 3) The SYSCALL_ERROR_HANDLER macro in
> >> sysdeps/unix/sysv/linux/sh/sysdep.h has been changed to use CFI
> >> directives to mark r12's save/restore.  The RTLD_PRIVATE_ERRNO version
> >> is not dealt with, because simply, r12 there is never saved.
> > 
> > Hmm, I don't quite understand how that code can get away with not
> > preserving r12 -- Kaz, do you have an explanation?  The code in question:
> 
> I don't remember any explanation.  Maybe just my oversight.
> I agree that r12 should be preserved there.

I found some more places, and now pushed the following as commit
58f902b8d8cd47e8f4f2fcd64721a6289400422e:

	* sysdeps/sh/____longjmp_chk.S (CALL_FAIL): Preserve r12 and pr
	registers for frame unwinding purposes, add CFI directives.
	* sysdeps/unix/sysv/linux/sh/____longjmp_chk.S (CALL_FAIL): Likewise.
	* sysdeps/unix/sysv/linux/sh/makecontext.S (.Lexitcode): Likewise
	* sysdeps/unix/sysv/linux/sh/sysdep.h (SYSCALL_ERROR_HANDLER):
	Likewise.

diff --git a/sysdeps/sh/____longjmp_chk.S b/sysdeps/sh/____longjmp_chk.S
index e8d5f68..b37a948 100644
--- a/sysdeps/sh/____longjmp_chk.S
+++ b/sysdeps/sh/____longjmp_chk.S
@@ -28,9 +28,16 @@ longjmp_msg:
 # define CALL_FAIL \
 	mov.l	.Lfail, r1;				\
 	mov.l	.Lstr, r4;				\
+	mov.l	r12, @-r15;				\
+	cfi_remember_state;				\
+	cfi_adjust_cfa_offset (4);			\
+	cfi_rel_offset (r12, 0);			\
 	mova	.Lgot, r0;				\
 	mov.l	.Lgot, r12;				\
 	add	r0, r12;				\
+	sts.l	pr, @-r15;				\
+	cfi_adjust_cfa_offset (4);			\
+	cfi_rel_offset (pr, 0);				\
 	bsrf	r1;					\
 	 add	r12, r4;				\
 	/* Unreachable.	 */				\
@@ -41,11 +48,16 @@ longjmp_msg:
 .Lstr:							\
 	.long	longjmp_msg@GOTOFF;			\
 .Lfail:							\
-	.long	__GI___fortify_fail@PLT-(.Lfail0-.);
+	.long	__GI___fortify_fail@PLT-(.Lfail0-.);	\
+	cfi_restore_state;
 #else
 # define CALL_FAIL \
 	mov.l	.Lfail, r1;				\
 	mov.l	.Lstr, r4;				\
+	sts.l	pr, @-r15;				\
+	cfi_remember_state;				\
+	cfi_adjust_cfa_offset (4);			\
+	cfi_rel_offset (pr, 0);				\
 	jsr	@r1;					\
 	 nop;						\
 	/* Unreachable.	 */				\
@@ -53,7 +65,8 @@ longjmp_msg:
 .Lstr:							\
 	.long	longjmp_msg;				\
 .Lfail:							\
-	.long	__fortify_fail;
+	.long	__fortify_fail;				\
+	cfi_restore_state;
 #endif
 
 #define CHECK_SP(reg) \
diff --git a/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S b/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S
index bcf828b..d74caa2 100644
--- a/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S
+++ b/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S
@@ -32,9 +32,16 @@ longjmp_msg:
 # define CALL_FAIL \
 	mov.l	.Lfail, r1;				\
 	mov.l	.Lstr, r4;				\
+	mov.l	r12, @-r15;				\
+	cfi_remember_state;				\
+	cfi_adjust_cfa_offset (4);			\
+	cfi_rel_offset (r12, 0);			\
 	mova	.Lgot, r0;				\
 	mov.l	.Lgot, r12;				\
 	add	r0, r12;				\
+	sts.l	pr, @-r15;				\
+	cfi_adjust_cfa_offset (4);			\
+	cfi_rel_offset (pr, 0);				\
 	bsrf	r1;					\
 	 add	r12, r4;				\
 .Lfail0:						\
@@ -45,11 +52,16 @@ longjmp_msg:
 .Lstr:							\
 	.long	longjmp_msg@GOTOFF;			\
 .Lfail:							\
-	.long	__GI___fortify_fail@PLT-(.Lfail0-.);
+	.long	__GI___fortify_fail@PLT-(.Lfail0-.);	\
+	cfi_restore_state;
 #else
 # define CALL_FAIL \
 	mov.l	.Lfail, r1;				\
 	mov.l	.Lstr, r4;				\
+	sts.l	pr, @-r15;				\
+	cfi_remember_state;				\
+	cfi_adjust_cfa_offset (4);			\
+	cfi_rel_offset (pr, 0);				\
 	jsr	@r1;					\
 	 nop;						\
 	/* Unreachable.	 */				\
@@ -57,7 +69,8 @@ longjmp_msg:
 .Lstr:							\
 	.long	longjmp_msg;				\
 .Lfail:							\
-	.long	__fortify_fail;
+	.long	__fortify_fail;				\
+	cfi_restore_state;
 #endif
 
 #define CHECK_SP(reg) \
diff --git a/sysdeps/unix/sysv/linux/sh/makecontext.S b/sysdeps/unix/sysv/linux/sh/makecontext.S
index ec9ce91..a04bc9f 100644
--- a/sysdeps/unix/sysv/linux/sh/makecontext.S
+++ b/sysdeps/unix/sysv/linux/sh/makecontext.S
@@ -97,8 +97,12 @@ ENTRY(__makecontext)
 	cfi_endproc
 
 	.align	5
+	cfi_startproc
 .Lexitcode:
 #ifdef PIC
+	mov.l	r12, @-r15
+	cfi_adjust_cfa_offset (4)
+	cfi_rel_offset (r12, 0)
 	mova	.Lgot, r0
 	mov.l	.Lgot, r12
 	add	r0, r12
@@ -107,6 +111,9 @@ ENTRY(__makecontext)
 	bt/s	2f
 	 mov	r8, r4		/* r4 <- ucb->uc_link */
 	mov.l	.Lsetcontext, r1
+	sts.l	pr, @-r15
+	cfi_adjust_cfa_offset (4)
+	cfi_rel_offset (pr, 0)
 #ifdef PIC
 	bsrf	r1
 .LPCS0:
@@ -115,6 +122,10 @@ ENTRY(__makecontext)
 	jsr	@r1
 	 nop
 #endif
+        /* Restore to keep CFI/CFA balanced.  */
+	lds.l	@r15+, pr
+	cfi_adjust_cfa_offset (-4)
+	cfi_restore (pr)
 	/* If this returns (which can happen if the syscall fails) we'll exit
 	   the program with the return error value (-1).  */
 
@@ -143,7 +154,6 @@ ENTRY(__makecontext)
 .Lexit:
 	.long	HIDDEN_JUMPTARGET(exit)
 #endif
-	cfi_startproc
 PSEUDO_END(__makecontext)
 
 weak_alias (__makecontext, makecontext)
diff --git a/sysdeps/unix/sysv/linux/sh/sysdep.h b/sysdeps/unix/sysv/linux/sh/sysdep.h
index 5215a84..ce72c66 100644
--- a/sysdeps/unix/sysv/linux/sh/sysdep.h
+++ b/sysdeps/unix/sysv/linux/sh/sysdep.h
@@ -100,11 +99,15 @@
 # if RTLD_PRIVATE_ERRNO
 #  define SYSCALL_ERROR_HANDLER	\
 	neg r0,r1; \
+	mov r12,r2; \
+	cfi_register (r12, r2); \
 	mov.l 0f,r12; \
 	mova 0f,r0; \
 	add r0,r12; \
 	mov.l 1f,r0; \
 	mov.l r1,@(r0,r12); \
+	mov r2,r12; \
+	cfi_restore (r12); \
 	bra .Lpseudo_end; \
 	 mov _IMM1,r0; \
 	.align 2; \
@@ -121,6 +124,7 @@
 #  define SYSCALL_ERROR_HANDLER \
 	neg r0,r1; \
 	mov r12,r2; \
+	cfi_register (r12, r2); \
 	mov.l 0f,r12; \
 	mova 0f,r0; \
 	add r0,r12; \
@@ -128,6 +132,7 @@
 	stc gbr, r4; \
 	mov.l @(r0,r12),r0; \
 	mov r2,r12; \
+	cfi_restore (r12); \
 	add r4,r0; \
 	mov.l r1,@r0; \
 	bra .Lpseudo_end; \
@@ -140,12 +145,14 @@
 #  define SYSCALL_ERROR_HANDLER						      \
 	neg r0,r1; \
 	mov r12,r2; \
+	cfi_register (r12, r2); \
 	mov.l 0f,r12; \
 	mova 0f,r0; \
 	add r0,r12; \
 	mov.l 1f,r0; \
 	mov.l @(r0,r12),r0; \
 	mov r2,r12; \
+	cfi_restore (r12); \
 	mov.l r1,@r0; \
 	bra .Lpseudo_end; \
 	 mov _IMM1,r0; \


GrÃÃe,
 Thomas

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