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mips, mips64 signal trampoline

PATCH In review Kip Walker 1 participant 2 messages Oct 18, 2002 MIPS

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Kip Walker

author
#0 lore raw

PATCH 1/1 mips, mips64 signal trampoline

It looks like the RA setup by setup_frame and setup_rt_frame in arch/mips64/kernel/signal.c and signal32.c can be wrong. Same for arch/mips/kernel/signal.c

signal32.c, 32-bit signal.c: sa_restorer is overriden signal.c: regs->regs[31] is pointed at the sigframe's code, even though there isn't code in the frame, and a comment says that sa_restorer is always used.

Patch for 2.4 attached.

Kip

Index: arch/mips64/kernel/signal.c
===================================================================
RCS file: /home/cvs/linux/arch/mips64/kernel/signal.c,v retrieving revision 1.19.2.5

mips64/kernel/signal.c +2 -4
diff -u -r1.19.2.5 signal.c
@@ -338,13 +338,12 @@
 	regs->regs[ 5] = 0;
 	regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->sf_code;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG
 	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 	       current->comm, current->pid,
-	       frame, regs->cp0_epc, frame->sf_code);
+	       frame, regs->cp0_epc, regs->regs[31]);
 #endif
         return;
 

@@ -402,13 +401,12 @@
 	regs->regs[ 5] = (unsigned long) &frame->rs_info;
 	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->rs_code;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG
 	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 	       current->comm, current->pid,
-	       frame, regs->cp0_epc, frame->rs_code);
+	       frame, regs->cp0_epc, regs->regs[31]);
 #endif
 	return;

Index: arch/mips64/kernel/signal32.c
===================================================================
RCS file: /home/cvs/linux/arch/mips64/kernel/signal32.c,v retrieving revision 1.20.2.9

mips64/kernel/signal32.c +2 -2
diff -u -r1.20.2.9 signal32.c
@@ -589,6 +589,7 @@
 		err |= __put_user(0x0000000c                 ,
 		                  frame->sf_code + 1);
 		flush_cache_sigtramp((unsigned long) frame->sf_code);
+		regs->regs[31] = (unsigned long) frame->sf_code;
 	}
 
 	err |= setup_sigcontext(regs, &frame->sf_sc);

@@ -610,7 +611,6 @@
 	regs->regs[ 5] = 0;
 	regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->sf_code;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG

@@ -653,6 +653,7 @@
 		err |= __put_user(0x0000000c                 ,
 		                  frame->rs_code + 1);
 		flush_cache_sigtramp((unsigned long) frame->rs_code);
+		regs->regs[31] = (unsigned long) frame->rs_code;
 	}
 
 	/* Convert (siginfo_t -> siginfo_t32) and copy to user. */

@@ -687,7 +688,6 @@
 	regs->regs[ 5] = (unsigned long) &frame->rs_info;
 	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->rs_code;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG
author
#1 lore raw

OK, the patch was broken because it changed regs->regs[31] before the setup_sigcontext. I think this one actually fixes a problem instead of introducing one. :-) Somebody sent the 32-bit part of the patch around a long time ago, but it doesn't seem to have gotten into CVS yet.

Kip

Quoted 5 lines · Kip Walker

It looks like the RA setup by setup_frame and setup_rt_frame in arch/mips64/kernel/signal.c and signal32.c can be wrong. Same for arch/mips/kernel/signal.c

Quoted 7 lines

signal32.c, 32-bit signal.c: sa_restorer is overriden signal.c: regs->regs[31] is pointed at the sigframe's code, even though there isn't code in the frame, and a comment says that sa_restorer is always used.

Patch for 2.4 attached.

Index: arch/mips/kernel/signal.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/kernel/signal.c,v retrieving revision 1.39.2.9

mips/kernel/signal.c +10 -6
diff -u -r1.39.2.9 signal.c
@@ -461,6 +461,7 @@
 	int signr, sigset_t *set)
 {
 	struct sigframe *frame;
+	unsigned long ra;
 	int err = 0;
 
 	frame = get_sigframe(ka, regs, sizeof(*frame));

@@ -470,7 +471,7 @@
 	/* Set up to return from userspace.  If provided, use a stub already
 	   in userspace.  */
 	if (ka->sa.sa_flags & SA_RESTORER)
-		regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
+		ra = (unsigned long) ka->sa.sa_restorer;
 	else {
 		/*
 		 * Set up the return code ...

@@ -483,6 +484,7 @@
 		err |= __put_user(0x0000000c                 ,
 		                  frame->sf_code + 1);
 		flush_cache_sigtramp((unsigned long) frame->sf_code);
+		ra = (unsigned long) frame->sf_code;
 	}
 
 	err |= setup_sigcontext(regs, &frame->sf_sc);

@@ -504,13 +506,13 @@
 	regs->regs[ 5] = 0;
 	regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->sf_code;
+	regs->regs[31] = ra;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG
 	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 	       current->comm, current->pid,
-	       frame, regs->cp0_epc, frame->sf_code);
+	       frame, regs->cp0_epc, regs->regs[31]);
 #endif
         return;
 

@@ -524,6 +526,7 @@
 	int signr, sigset_t *set, siginfo_t *info)
 {
 	struct rt_sigframe *frame;
+	unsigned long ra;
 	int err = 0;
 
 	frame = get_sigframe(ka, regs, sizeof(*frame));

@@ -533,7 +536,7 @@
 	/* Set up to return from userspace.  If provided, use a stub already
 	   in userspace.  */
 	if (ka->sa.sa_flags & SA_RESTORER)
-		regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
+		ra = (unsigned long) ka->sa.sa_restorer;
 	else {
 		/*
 		 * Set up the return code ...

@@ -546,6 +549,7 @@
 		err |= __put_user(0x0000000c                 ,
 		                  frame->rs_code + 1);
 		flush_cache_sigtramp((unsigned long) frame->rs_code);
+		ra = (unsigned long) frame->rs_code;
 	}
 
 	/* Create siginfo.  */

@@ -580,13 +584,13 @@
 	regs->regs[ 5] = (unsigned long) &frame->rs_info;
 	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->rs_code;
+	regs->regs[31] = ra;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG
 	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 	       current->comm, current->pid,
-	       frame, regs->cp0_epc, frame->rs_code);
+	       frame, regs->cp0_epc, regs->regs[31]);
 #endif
 	return;

Index: arch/mips64/kernel/signal.c
===================================================================
RCS file: /home/cvs/linux/arch/mips64/kernel/signal.c,v retrieving revision 1.19.2.5

mips64/kernel/signal.c +9 -19
diff -u -r1.19.2.5 signal.c
@@ -313,12 +313,6 @@
 	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 		goto give_sigsegv;
 
-	/*
-	 * Set up to return from userspace.  On mips64 we always use a stub 
-	 * already provided by userspace and ignore SA_RESTORER.
-	 */
-	regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
-
 	err |= setup_sigcontext(regs, &frame->sf_sc);
 	err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 	if (err)

@@ -331,20 +325,21 @@
 	 *   a1 = 0 (should be cause)
 	 *   a2 = pointer to struct sigcontext
 	 *
-	 * $25 and c0_epc point to the signal handler, $29 points to the
-	 * struct sigframe.
+	 * $25 and c0_epc point to the signal handler, $29 points to
+	 * the struct sigframe.  On mips64 we always use a stub
+	 * already provided by userspace and ignore SA_RESTORER.
 	 */
 	regs->regs[ 4] = signr;
 	regs->regs[ 5] = 0;
 	regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->sf_code;
+	regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG
 	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 	       current->comm, current->pid,
-	       frame, regs->cp0_epc, frame->sf_code);
+	       frame, regs->cp0_epc, regs->regs[31]);
 #endif
         return;
 

@@ -364,12 +359,6 @@
 	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 		goto give_sigsegv;
 
-	/*
-	 * Set up to return from userspace.  On mips64 we always use a stub 
-	 * already provided by userspace and ignore SA_RESTORER.
-	 */
-	regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
-
 	/* Create siginfo.  */
 	err |= copy_siginfo_to_user(&frame->rs_info, info);
 

@@ -396,19 +385,20 @@
 	 *   a2 = pointer to ucontext
 	 *
 	 * $25 and c0_epc point to the signal handler, $29 points to
-	 * the struct rt_sigframe.
+	 * the struct rt_sigframe.  On mips64 we always use a stub
+	 * already provided by userspace and ignore SA_RESTORER.
 	 */
 	regs->regs[ 4] = signr;
 	regs->regs[ 5] = (unsigned long) &frame->rs_info;
 	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->rs_code;
+	regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG
 	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 	       current->comm, current->pid,
-	       frame, regs->cp0_epc, frame->rs_code);
+	       frame, regs->cp0_epc, regs->regs[31]);
 #endif
 	return;

Index: arch/mips64/kernel/signal32.c
===================================================================
RCS file: /home/cvs/linux/arch/mips64/kernel/signal32.c,v retrieving revision 1.20.2.9

mips64/kernel/signal32.c +10 -6
diff -u -r1.20.2.9 signal32.c
@@ -567,6 +567,7 @@
 			       int signr, sigset_t *set)
 {
 	struct sigframe *frame;
+	unsigned long ra;
 	int err = 0;
 
 	frame = get_sigframe(ka, regs, sizeof(*frame));

@@ -576,7 +577,7 @@
 	/* Set up to return from userspace.  If provided, use a stub already
 	   in userspace.  */
 	if (ka->sa.sa_flags & SA_RESTORER)
-		regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
+		ra = (unsigned long) ka->sa.sa_restorer;
 	else {
 		/*
 		 * Set up the return code ...

@@ -589,6 +590,7 @@
 		err |= __put_user(0x0000000c                 ,
 		                  frame->sf_code + 1);
 		flush_cache_sigtramp((unsigned long) frame->sf_code);
+		ra = (unsigned long) frame->sf_code;
 	}
 
 	err |= setup_sigcontext(regs, &frame->sf_sc);

@@ -610,13 +612,13 @@
 	regs->regs[ 5] = 0;
 	regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->sf_code;
+	regs->regs[31] = ra;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG
 	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 	       current->comm, current->pid,
-	       frame, regs->cp0_epc, frame->sf_code);
+	       frame, regs->cp0_epc, regs->regs[31]);
 #endif
         return;
 

@@ -631,6 +633,7 @@
 				  sigset_t *set, siginfo_t *info)
 {
 	struct rt_sigframe32 *frame;
+	unsigned long ra;
 	int err = 0;
 
 	frame = get_sigframe(ka, regs, sizeof(*frame));

@@ -640,7 +643,7 @@
 	/* Set up to return from userspace.  If provided, use a stub already
 	   in userspace.  */
 	if (ka->sa.sa_flags & SA_RESTORER)
-		regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
+		ra = (unsigned long) ka->sa.sa_restorer;
 	else {
 		/*
 		 * Set up the return code ...

@@ -653,6 +656,7 @@
 		err |= __put_user(0x0000000c                 ,
 		                  frame->rs_code + 1);
 		flush_cache_sigtramp((unsigned long) frame->rs_code);
+		ra = (unsigned long) frame->rs_code;
 	}
 
 	/* Convert (siginfo_t -> siginfo_t32) and copy to user. */

@@ -687,13 +691,13 @@
 	regs->regs[ 5] = (unsigned long) &frame->rs_info;
 	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 	regs->regs[29] = (unsigned long) frame;
-	regs->regs[31] = (unsigned long) frame->rs_code;
+	regs->regs[31] = ra;
 	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 
 #if DEBUG_SIG
 	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 	       current->comm, current->pid,
-	       frame, regs->cp0_epc, frame->rs_code);
+	       frame, regs->cp0_epc, regs->regs[31]);
 #endif
 	return;