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sh: BUG() handling through trapa vector.

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Previously we haven't been doing anything with verbose BUG() reporting,
and we've been relying on the oops path for handling BUG()'s, which is
rather sub-optimal.

This switches BUG handling to use a fixed trapa vector (#0x3e) where we
construct a small bug frame post trapa instruction to get the context
right. This also makes it trivial to wire up a DIE_BUG for the atomic
die chain, which we couldn't really do before.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Paul Mundt 2006-12-08 17:41:43 +09:00
parent 1b73e6ae45
commit dc34d312c7
3 changed files with 89 additions and 9 deletions
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10
arch/sh/kernel/process.c
View file

@ -498,6 +498,16 @@ asmlinkage void break_point_trap_software(unsigned long r4, unsigned long r5,
{
struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
/* Rewind */
regs->pc -= 2;
#ifdef CONFIG_BUG
if (__kernel_text_address(instruction_pointer(regs))) {
u16 insn = *(u16 *)instruction_pointer(regs);
if (insn == TRAPA_BUG_OPCODE)
handle_BUG(regs);
}
#endif
force_sig(SIGTRAP, current);
}

35
arch/sh/kernel/traps.c
View file

@ -19,6 +19,7 @@
#include <linux/kallsyms.h>
#include <linux/io.h>
#include <linux/debug_locks.h>
#include <linux/limits.h>
#include <asm/system.h>
#include <asm/uaccess.h>
@ -129,6 +130,40 @@ static int die_if_no_fixup(const char * str, struct pt_regs * regs, long err)
return -EFAULT;
}
#ifdef CONFIG_BUG
#ifdef CONFIG_DEBUG_BUGVERBOSE
static inline void do_bug_verbose(struct pt_regs *regs)
{
struct bug_frame f;
long len;
if (__copy_from_user(&f, (const void __user *)regs->pc,
sizeof(struct bug_frame)))
return;
len = __strnlen_user(f.file, PATH_MAX) - 1;
if (unlikely(len < 0 || len >= PATH_MAX))
f.file = "<bad filename>";
len = __strnlen_user(f.func, PATH_MAX) - 1;
if (unlikely(len < 0 || len >= PATH_MAX))
f.func = "<bad function>";
printk(KERN_ALERT "kernel BUG in %s() at %s:%d!\n",
f.func, f.file, f.line);
}
#else
static inline void do_bug_verbose(struct pt_regs *regs)
{
}
#endif /* CONFIG_DEBUG_BUGVERBOSE */
#endif /* CONFIG_BUG */
void handle_BUG(struct pt_regs *regs)
{
do_bug_verbose(regs);
die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff);
}
/*
* handle an instruction that does an unaligned memory access by emulating the
* desired behaviour

53
include/asm-sh/bug.h
View file

@ -1,19 +1,54 @@
#ifndef __ASM_SH_BUG_H
#define __ASM_SH_BUG_H
#ifdef CONFIG_BUG
/*
* Tell the user there is some problem.
*/
#define BUG() do { \
printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); \
*(volatile int *)0 = 0; \
struct bug_frame {
unsigned short opcode;
unsigned short line;
const char *file;
const char *func;
};
struct pt_regs;
extern void handle_BUG(struct pt_regs *);
#define TRAPA_BUG_OPCODE 0xc33e /* trapa #0x3e */
#ifdef CONFIG_DEBUG_BUGVERBOSE
#define BUG() \
do { \
__asm__ __volatile__ ( \
".align 2\n\t" \
".short %O0\n\t" \
".short %O1\n\t" \
".long %O2\n\t" \
".long %O3\n\t" \
: \
: "n" (TRAPA_BUG_OPCODE), \
"i" (__LINE__), "X" (__FILE__), \
"X" (__FUNCTION__)); \
} while (0)
#else
#define BUG() \
do { \
__asm__ __volatile__ ( \
".align 2\n\t" \
".short %O0\n\t" \
: \
: "n" (TRAPA_BUG_OPCODE)); \
} while (0)
#endif /* CONFIG_DEBUG_BUGVERBOSE */
#define HAVE_ARCH_BUG
#endif
#endif /* CONFIG_BUG */
#include <asm-generic/bug.h>
#endif
#endif /* __ASM_SH_BUG_H */