SH: ____longjmp_chk for GNU/Linux with sigaltstack support

[Thomas Schwinge]

Hi!

This one is based on Joseph's suggestions as posted in
<http://sourceware.org/ml/libc-ports/2009-08/msg00002.html>; a part of
the following assembler bits are what »gcc -O2 -S« produced for Joseph's
C code.  No regressions and debug/tst-longjmp_chk2 now passes -- Kaz,
would you please review this patch?

	* sysdeps/unix/sysv/linux/sh/____longjmp_chk.S: New file, based on
	sysdeps/sh/____longjmp_chk.S.
	* sysdeps/unix/sysv/linux/sh/sigaltstack-offsets.sym: New file, based
	on sysdeps/unix/sysv/linux/x86_64/sigaltstack-offsets.sym.
	* sysdeps/unix/sysv/linux/sh/Makefile [subdir=misc]
	(gen-as-const-headers): Append sigaltstack-offsets.sym.

diff --git a/sysdeps/unix/sysv/linux/sh/Makefile b/sysdeps/unix/sysv/linux/sh/Makefile
index 1ead8f2..dd3b382 100644
--- a/sysdeps/unix/sysv/linux/sh/Makefile
+++ b/sysdeps/unix/sysv/linux/sh/Makefile
@@ -6,6 +6,10 @@ ifeq ($(subdir),stdlib)
 gen-as-const-headers += ucontext_i.sym
 endif
 
+ifeq ($(subdir),misc)
+gen-as-const-headers += sigaltstack-offsets.sym
+endif
+
 ifeq ($(subdir),math)
 # The libm.so link can't find __fpscr_values
 libm.so-no-z-defs = yes
diff --git a/sysdeps/sh/____longjmp_chk.S b/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S
similarity index 59%
copy from sysdeps/sh/____longjmp_chk.S
copy to sysdeps/unix/sysv/linux/sh/____longjmp_chk.S
index 5d17f3a..8e83112 100644
--- a/sysdeps/sh/____longjmp_chk.S
+++ b/sysdeps/unix/sysv/linux/sh/____longjmp_chk.S
@@ -1,4 +1,4 @@
-/* Copyright (C) 2009 Free Software Foundation, Inc.
+/* Copyright (C) 2009-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -15,6 +15,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include <sysdep.h>
+
+#include <sigaltstack-offsets.h>
+
 	.section .rodata.str1.1,"aMS",@progbits,1
 	.type	longjmp_msg,@object
 longjmp_msg:
@@ -61,9 +65,39 @@ longjmp_msg:
 #endif
 
 #define CHECK_SP(reg) \
-	cmp/hs	r15, reg;				\
-	bt	.Lok;					\
-	CALL_FAIL					\
+	/* Jumping to a higher-address frame is always allowed.	 */	\
+	cmp/hs	r15, reg;						\
+	bt	.Lok;							\
+									\
+	mov.l	r0, @-r15; /* The return value is already in here.  */	\
+	mov.l	r1, @-r15; /* PTR_DEMANGLE helper.  */			\
+	mov.l	r2, @-r15; /* The new SP value is already in here.  */	\
+	mov.l	r4, @-r15; /* We'll still need this one.  */		\
+	add	#-sizeSS, r15;						\
+	mov	#0, r4;							\
+	mov	r15, r5;						\
+	DO_CALL(sigaltstack, 2);					\
+	/* Without working sigaltstack we cannot perform the test.  */	\
+	tst	r0, r0;							\
+	bf	.Lok2;							\
+	mov.l	@(oSS_FLAGS, r15), r0;					\
+	tst	#SS_ONSTACK, r0;					\
+	bt	.Lcall_fail;						\
+	mov.l	@(oSS_SIZE, r15), r2;					\
+	mov.l	@(oSS_SP, r15), r1;					\
+	add	r2, r1;							\
+	sub	r8, r1;							\
+	cmp/hi	r1, r2;							\
+	bf	.Lok2;							\
+.Lcall_fail:								\
+	CALL_FAIL							\
+									\
+.Lok2:									\
+	add	#sizeSS, r15;						\
+	mov.l	@r15+, r4;						\
+	mov.l	@r15+, r2;						\
+	mov.l	@r15+, r1;						\
+	mov.l	@r15+, r0;						\
 .Lok:
 
 #include <__longjmp.S>
diff --git a/sysdeps/unix/sysv/linux/x86_64/sigaltstack-offsets.sym b/sysdeps/unix/sysv/linux/sh/sigaltstack-offsets.sym
similarity index 80%
copy from sysdeps/unix/sysv/linux/x86_64/sigaltstack-offsets.sym
copy to sysdeps/unix/sysv/linux/sh/sigaltstack-offsets.sym
index 5ff3af4..f734469 100644
--- a/sysdeps/unix/sysv/linux/x86_64/sigaltstack-offsets.sym
+++ b/sysdeps/unix/sysv/linux/sh/sigaltstack-offsets.sym
@@ -1,7 +1,3 @@
-#ifndef _XOPEN_EXTENDED
-# define _XOPEN_EXTENDED
-#endif
-
 #include <stddef.h>
 #include <signal.h>
 
@@ -11,5 +7,7 @@
 
 sizeSS				sizeof (stack_t)
 oSS_SP				sigaltstack (ss_sp)
-oSS_SIZE			sigaltstack (ss_size)
 oSS_FLAGS			sigaltstack (ss_flags)
+oSS_SIZE			sigaltstack (ss_size)
+
+SS_ONSTACK


Grüße,
 Thomas
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