[PATCH 0/3] m68k: Allow all kernel traps to be handled via exception fixups

[PATCH 0/3] m68k: Allow all kernel traps to be handled via exception fixups

[Geert Uytterhoeven]

This patch series is a split and cleanup of the single commit
aa8fcffdec0ac8d0ace3af622eb92f5ee804fc44
("m68k-allow-all-kernel-traps-to-be-handled-via-exception-fixups-all.diff"),
which dates back to the Linux/m68k CVS tree.

It's a prerequisite for ARAnyM support.

    [PATCH 1/3] m68k: Add helper function handle_kernel_fault()
    [PATCH 2/3] m68k: Use base_trap_init() to initialize vectors
    [PATCH 3/3] m68k: Allow all kernel traps to be handled via exception fixups

 arch/m68k/kernel/traps.c            |   10 +++++++---
 b/arch/m68k/include/asm/processor.h |    2 ++
 b/arch/m68k/kernel/signal.c         |   24 +++++++++++++++++++++++-
 b/arch/m68k/kernel/traps.c          |   10 +++++-----
 b/arch/m68k/mm/fault.c              |   16 +---------------
 5 files changed, 38 insertions(+), 24 deletions(-)

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

[PATCH 1/3] m68k: Add helper function handle_kernel_fault()

[Geert Uytterhoeven]

From: Roman Zippel <zippel@linux-m68k.org>

Add helper function handle_kernel_fault() in signal.c, so frame_extra_sizes
can become static, and to avoid future code duplication.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 arch/m68k/include/asm/processor.h |    2 ++
 arch/m68k/kernel/signal.c         |   24 +++++++++++++++++++++++-
 arch/m68k/mm/fault.c              |   16 +---------------
 3 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/arch/m68k/include/asm/processor.h b/arch/m68k/include/asm/processor.h
index 7a6a759..f83cf9f 100644
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -110,6 +110,8 @@ static inline void start_thread(struct pt_regs * regs, unsigned long pc,
 	wrusp(usp);
 }
 
+extern int handle_kernel_fault(struct pt_regs *regs);
+
 #else
 
 /*
diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index d12c3b0..a0afc23 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -42,6 +42,7 @@
 #include <linux/personality.h>
 #include <linux/tty.h>
 #include <linux/binfmts.h>
+#include <linux/module.h>
 
 #include <asm/setup.h>
 #include <asm/uaccess.h>
@@ -51,7 +52,7 @@
 
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 
-const int frame_extra_sizes[16] = {
+static const int frame_extra_sizes[16] = {
   [1]	= -1, /* sizeof(((struct frame *)0)->un.fmt1), */
   [2]	= sizeof(((struct frame *)0)->un.fmt2),
   [3]	= sizeof(((struct frame *)0)->un.fmt3),
@@ -69,6 +70,27 @@ const int frame_extra_sizes[16] = {
   [15]	= -1, /* sizeof(((struct frame *)0)->un.fmtf), */
 };
 
+int handle_kernel_fault(struct pt_regs *regs)
+{
+	const struct exception_table_entry *fixup;
+	struct pt_regs *tregs;
+
+	/* Are we prepared to handle this kernel fault? */
+	fixup = search_exception_tables(regs->pc);
+	if (!fixup)
+		return 0;
+
+	/* Create a new four word stack frame, discarding the old one. */
+	regs->stkadj = frame_extra_sizes[regs->format];
+	tregs =	(struct pt_regs *)((long)regs + regs->stkadj);
+	tregs->vector = regs->vector;
+	tregs->format = 0;
+	tregs->pc = fixup->fixup;
+	tregs->sr = regs->sr;
+
+	return 1;
+}
+
 /*
  * Atomically swap in the new signal mask, and wait for a signal.
  */
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index a96394a..2db6099 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -18,7 +18,6 @@
 #include <asm/pgalloc.h>
 
 extern void die_if_kernel(char *, struct pt_regs *, long);
-extern const int frame_extra_sizes[]; /* in m68k/kernel/signal.c */
 
 int send_fault_sig(struct pt_regs *regs)
 {
@@ -35,21 +34,8 @@ int send_fault_sig(struct pt_regs *regs)
 		force_sig_info(siginfo.si_signo,
 			       &siginfo, current);
 	} else {
-		const struct exception_table_entry *fixup;
-
-		/* Are we prepared to handle this kernel fault? */
-		if ((fixup = search_exception_tables(regs->pc))) {
-			struct pt_regs *tregs;
-			/* Create a new four word stack frame, discarding the old
-			   one.  */
-			regs->stkadj = frame_extra_sizes[regs->format];
-			tregs =	(struct pt_regs *)((ulong)regs + regs->stkadj);
-			tregs->vector = regs->vector;
-			tregs->format = 0;
-			tregs->pc = fixup->fixup;
-			tregs->sr = regs->sr;
+		if (handle_kernel_fault(regs))
 			return -1;
-		}
 
 		//if (siginfo.si_signo == SIGBUS)
 		//	force_sig_info(siginfo.si_signo,
-- 
1.7.0.4

[PATCH 2/3] m68k: Use base_trap_init() to initialize vectors

[Geert Uytterhoeven]

From: Roman Zippel <zippel@linux-m68k.org>

So basic initialization is all in one place.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 arch/m68k/kernel/traps.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index ada4f4c..cd802d4 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -48,10 +48,7 @@ asmlinkage void nmihandler(void);
 asmlinkage void fpu_emu(void);
 #endif
 
-e_vector vectors[256] = {
-	[VEC_BUSERR]	= buserr,
-	[VEC_SYS]	= system_call,
-};
+e_vector vectors[256];
 
 /* nmi handler for the Amiga */
 asm(".text\n"
@@ -64,7 +61,7 @@ asm(".text\n"
  */
 void __init base_trap_init(void)
 {
-	if(MACH_IS_SUN3X) {
+	if (MACH_IS_SUN3X) {
 		extern e_vector *sun3x_prom_vbr;
 
 		__asm__ volatile ("movec %%vbr, %0" : "=r" (sun3x_prom_vbr));
@@ -79,6 +76,9 @@ void __init base_trap_init(void)
 
 		vectors[VEC_UNIMPII] = unimp_vec;
 	}
+
+	vectors[VEC_BUSERR] = buserr;
+	vectors[VEC_SYS] = system_call;
 }
 
 void __init trap_init (void)
-- 
1.7.0.4

[PATCH 3/3] m68k: Allow all kernel traps to be handled via exception fixups

[Geert Uytterhoeven]

From: Andreas Schwab <schwab@suse.de>

This will be needed by the ARAnyM Native Feature initialization code.
Also document that the VEC_TRACE check is needed for 68020/30.

Signed-off-by: Andreas Schwab <schwab@suse.de>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 arch/m68k/kernel/traps.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index cd802d4..4022bbc 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -58,6 +58,7 @@ asm(".text\n"
 /*
  * this must be called very early as the kernel might
  * use some instruction that are emulated on the 060
+ * and so we're prepared for early probe attempts (e.g. nf_init).
  */
 void __init base_trap_init(void)
 {
@@ -78,6 +79,7 @@ void __init base_trap_init(void)
 	}
 
 	vectors[VEC_BUSERR] = buserr;
+	vectors[VEC_ILLEGAL] = trap;
 	vectors[VEC_SYS] = system_call;
 }
 
@@ -1055,9 +1057,11 @@ asmlinkage void trap_c(struct frame *fp)
 	siginfo_t info;
 
 	if (fp->ptregs.sr & PS_S) {
-		if ((fp->ptregs.vector >> 2) == VEC_TRACE) {
-			/* traced a trapping instruction */
-		} else
+		if (fp->ptregs.vector == VEC_TRACE << 2) {
+			/* traced a trapping instruction on a 68020/30,
+			 * real exception will be executed afterwards.
+			 */
+		} else if (!handle_kernel_fault(&fp->ptregs))
 			bad_super_trap(fp);
 		return;
 	}
-- 
1.7.0.4