m68knommu: fix signal handling return path

PATCH New Greg Ungerer 1 participant 1 message May 1, 2008

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Greg Ungerer

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2008-05-01 02:17 UTC #0 lore raw

PATCH 1/1 m68knommu: fix signal handling return path

From: Wilson Callan <[email protected]>

The return from software signal handling pushes code on the stack that system calls to the kernels cleanup code. This is borrowed directly from the m68k linux signal handler.

The rt signal case is not quite right for the restricted instruction set of the ColdFire parts. And neither the normal signal case or rt signal case properly flushes/pushes the appropriate cache lines.

Rework the return path to just call back through some code fragments in the kernel proper (with no MMU in the way we can do this). No cache problems, and less code overall.

Original patch submitted by Wilson Callan <[email protected]>

Greg fixed the rt signal return path to use the proper system call

Signed-off-by Greg Ungerer <[email protected]>

---

arch/m68knommu/kernel/entry.S +9 -0

diff -Naurp linux-2.6.25/arch/m68knommu/kernel/entry.S linux-2.6.25-uc0/arch/m68knommu/kernel/entry.S
@@ -32,6 +32,7 @@
 #include <asm/segment.h>
 #include <asm/asm-offsets.h>
 #include <asm/entry.h>
+#include <asm/unistd.h>
 
 .text

@@ -140,3 +141,11 @@ ENTRY(sys_rt_sigreturn)
 	RESTORE_SWITCH_STACK
 	rts
 
+ENTRY(ret_from_user_signal)
+	moveq #__NR_sigreturn,%d0
+	trap #0
+
+ENTRY(ret_from_user_rt_signal)
+	move #__NR_rt_sigreturn,%d0
+	trap #0
+

arch/m68knommu/kernel/signal.c +4 ~~-17~~

diff -Naurp linux-2.6.25/arch/m68knommu/kernel/signal.c linux-2.6.25-uc0/arch/m68knommu/kernel/signal.c
@@ -51,6 +51,8 @@
 
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 
+void ret_from_user_signal(void);
+void ret_from_user_rt_signal(void);
 asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs);
 
 /*

@@ -539,10 +541,6 @@ static inline int rt_setup_ucontext(stru
 	return err;
 }
 
-static inline void push_cache (unsigned long vaddr)
-{
-}
-
 static inline void *
 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
 {

@@ -586,16 +584,11 @@ static void setup_frame (int sig, struct
 	err |= copy_to_user (&frame->sc, &context, sizeof(context));
 
 	/* Set up to return from userspace.  */
-	err |= __put_user(frame->retcode, &frame->pretcode);
-	/* moveq #,d0; trap #0 */
-	err |= __put_user(0x70004e40 + (__NR_sigreturn << 16),
-			  (long *)(frame->retcode));
+	err |= __put_user((void *) ret_from_user_signal, &frame->pretcode);
 
 	if (err)
 		goto give_sigsegv;
 
-	push_cache ((unsigned long) &frame->retcode);
-
 	/* Set up registers for signal handler */
 	wrusp ((unsigned long) frame);
 	regs->pc = (unsigned long) ka->sa.sa_handler;

@@ -655,17 +648,11 @@ static void setup_rt_frame (int sig, str
 	err |= copy_to_user (&frame->uc.uc_sigmask, set, sizeof(*set));
 
 	/* Set up to return from userspace.  */
-	err |= __put_user(frame->retcode, &frame->pretcode);
-	/* moveq #,d0; notb d0; trap #0 */
-	err |= __put_user(0x70004600 + ((__NR_rt_sigreturn ^ 0xff) << 16),
-			  (long *)(frame->retcode + 0));
-	err |= __put_user(0x4e40, (short *)(frame->retcode + 4));
+	err |= __put_user((void *) ret_from_user_rt_signal, &frame->pretcode);
 
 	if (err)
 		goto give_sigsegv;
 
-	push_cache ((unsigned long) &frame->retcode);
-
 	/* Set up registers for signal handler */
 	wrusp ((unsigned long) frame);
 	regs->pc = (unsigned long) ka->sa.sa_handler;