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authorPaul Mackerras <paulus@samba.org>2005-09-10 07:13:11 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-10 13:15:11 -0400
commitbb0bb3b6596cdb08adb0b72453cc67d48e139c2c (patch)
treef9116ed650d499d405a3fe021c473f9558897d96
parent1e63bc7342c40f0f1dd83d80d368665bd06f4963 (diff)
[PATCH] ppc32: Kill init on unhandled synchronous signals
This is a patch that I have had in my tree for ages. If init causes an exception that raises a signal, such as a SIGSEGV, SIGILL or SIGFPE, and it hasn't registered a handler for it, we don't deliver the signal, since init doesn't get any signals that it doesn't have a handler for. But that means that we just return to userland and generate the same exception again immediately. With this patch we print a message and kill init in this situation. This is very useful when you have a bug in the kernel that means that init doesn't get as far as executing its first instruction. :) Without this patch the system hangs when it gets to starting the userland init; with it you at least get a message giving you a clue about what has gone wrong. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/ppc/kernel/traps.c22
-rw-r--r--arch/ppc/mm/fault.c6
-rw-r--r--include/asm-ppc/system.h1
3 files changed, 24 insertions, 5 deletions
diff --git a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c
index 8356d544fa60..961ede87be72 100644
--- a/arch/ppc/kernel/traps.c
+++ b/arch/ppc/kernel/traps.c
@@ -118,6 +118,28 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
118 info.si_code = code; 118 info.si_code = code;
119 info.si_addr = (void __user *) addr; 119 info.si_addr = (void __user *) addr;
120 force_sig_info(signr, &info, current); 120 force_sig_info(signr, &info, current);
121
122 /*
123 * Init gets no signals that it doesn't have a handler for.
124 * That's all very well, but if it has caused a synchronous
125 * exception and we ignore the resulting signal, it will just
126 * generate the same exception over and over again and we get
127 * nowhere. Better to kill it and let the kernel panic.
128 */
129 if (current->pid == 1) {
130 __sighandler_t handler;
131
132 spin_lock_irq(&current->sighand->siglock);
133 handler = current->sighand->action[signr-1].sa.sa_handler;
134 spin_unlock_irq(&current->sighand->siglock);
135 if (handler == SIG_DFL) {
136 /* init has generated a synchronous exception
137 and it doesn't have a handler for the signal */
138 printk(KERN_CRIT "init has generated signal %d "
139 "but has no handler for it\n", signr);
140 do_exit(signr);
141 }
142 }
121} 143}
122 144
123/* 145/*
diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c
index 57d9930843ac..ee5e9f25baf9 100644
--- a/arch/ppc/mm/fault.c
+++ b/arch/ppc/mm/fault.c
@@ -278,11 +278,7 @@ bad_area:
278 278
279 /* User mode accesses cause a SIGSEGV */ 279 /* User mode accesses cause a SIGSEGV */
280 if (user_mode(regs)) { 280 if (user_mode(regs)) {
281 info.si_signo = SIGSEGV; 281 _exception(SIGSEGV, regs, code, address);
282 info.si_errno = 0;
283 info.si_code = code;
284 info.si_addr = (void __user *) address;
285 force_sig_info(SIGSEGV, &info, current);
286 return 0; 282 return 0;
287 } 283 }
288 284
diff --git a/include/asm-ppc/system.h b/include/asm-ppc/system.h
index 513a334c5810..d754ab570fe0 100644
--- a/include/asm-ppc/system.h
+++ b/include/asm-ppc/system.h
@@ -88,6 +88,7 @@ extern void *cacheable_memcpy(void *, const void *, unsigned int);
88extern int do_page_fault(struct pt_regs *, unsigned long, unsigned long); 88extern int do_page_fault(struct pt_regs *, unsigned long, unsigned long);
89extern void bad_page_fault(struct pt_regs *, unsigned long, int); 89extern void bad_page_fault(struct pt_regs *, unsigned long, int);
90extern void die(const char *, struct pt_regs *, long); 90extern void die(const char *, struct pt_regs *, long);
91extern void _exception(int, struct pt_regs *, int, unsigned long);
91#ifdef CONFIG_BOOKE_WDT 92#ifdef CONFIG_BOOKE_WDT
92extern u32 booke_wdt_enabled; 93extern u32 booke_wdt_enabled;
93extern u32 booke_wdt_period; 94extern u32 booke_wdt_period;