forked from Minki/linux
abd4f7505b
This patch makes the i386 behave the same way that x86_64 does when a
segfault happens. A line gets printed to the kernel log so that tools
that need to check for failures can behave more uniformly between
debug.show_unhandled_signals sysctl variable to 0 (or by doing echo 0 >
/proc/sys/debug/exception-trace)
Also, all of the lines being printed are now using printk_ratelimit() to
deny the ability of DoS from a local user with a program like the
following:
main()
{
while (1)
if (!fork()) *(int *)0 = 0;
}
This new revision also includes the fix that Andrew did which got rid of
new sysctl that was added to the system in earlier versions of this.
Also, 'show-unhandled-signals' sysctl has been renamed back to the old
'exception-trace' to avoid breakage of people's scripts.
AK: Enabling by default for i386 will be likely controversal, but let's see what happens
AK: Really folks, before complaining just fix your segfaults
AK: I bet this will find a lot of silent issues
Signed-off-by: Masoud Sharbiani <masouds@google.com>
Signed-off-by: Andi Kleen <ak@suse.de>
[ Personally, I've found the complaints useful on x86-64, so I'm all for
this. That said, I wonder if we could do it more prettily.. -Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
377 lines
10 KiB
C
377 lines
10 KiB
C
#ifndef _LINUX_SIGNAL_H
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#define _LINUX_SIGNAL_H
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#include <asm/signal.h>
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#include <asm/siginfo.h>
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#ifdef __KERNEL__
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#include <linux/list.h>
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/*
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* Real Time signals may be queued.
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*/
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struct sigqueue {
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struct list_head list;
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int flags;
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siginfo_t info;
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struct user_struct *user;
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};
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/* flags values. */
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#define SIGQUEUE_PREALLOC 1
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struct sigpending {
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struct list_head list;
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sigset_t signal;
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};
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/*
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* Define some primitives to manipulate sigset_t.
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*/
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#ifndef __HAVE_ARCH_SIG_BITOPS
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#include <linux/bitops.h>
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/* We don't use <linux/bitops.h> for these because there is no need to
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be atomic. */
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static inline void sigaddset(sigset_t *set, int _sig)
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{
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unsigned long sig = _sig - 1;
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if (_NSIG_WORDS == 1)
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set->sig[0] |= 1UL << sig;
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else
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set->sig[sig / _NSIG_BPW] |= 1UL << (sig % _NSIG_BPW);
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}
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static inline void sigdelset(sigset_t *set, int _sig)
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{
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unsigned long sig = _sig - 1;
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if (_NSIG_WORDS == 1)
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set->sig[0] &= ~(1UL << sig);
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else
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set->sig[sig / _NSIG_BPW] &= ~(1UL << (sig % _NSIG_BPW));
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}
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static inline int sigismember(sigset_t *set, int _sig)
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{
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unsigned long sig = _sig - 1;
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if (_NSIG_WORDS == 1)
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return 1 & (set->sig[0] >> sig);
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else
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return 1 & (set->sig[sig / _NSIG_BPW] >> (sig % _NSIG_BPW));
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}
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static inline int sigfindinword(unsigned long word)
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{
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return ffz(~word);
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}
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#endif /* __HAVE_ARCH_SIG_BITOPS */
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static inline int sigisemptyset(sigset_t *set)
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{
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extern void _NSIG_WORDS_is_unsupported_size(void);
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switch (_NSIG_WORDS) {
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case 4:
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return (set->sig[3] | set->sig[2] |
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set->sig[1] | set->sig[0]) == 0;
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case 2:
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return (set->sig[1] | set->sig[0]) == 0;
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case 1:
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return set->sig[0] == 0;
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default:
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_NSIG_WORDS_is_unsupported_size();
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return 0;
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}
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}
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#define sigmask(sig) (1UL << ((sig) - 1))
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#ifndef __HAVE_ARCH_SIG_SETOPS
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#include <linux/string.h>
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#define _SIG_SET_BINOP(name, op) \
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static inline void name(sigset_t *r, const sigset_t *a, const sigset_t *b) \
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{ \
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extern void _NSIG_WORDS_is_unsupported_size(void); \
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unsigned long a0, a1, a2, a3, b0, b1, b2, b3; \
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\
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switch (_NSIG_WORDS) { \
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case 4: \
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a3 = a->sig[3]; a2 = a->sig[2]; \
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b3 = b->sig[3]; b2 = b->sig[2]; \
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r->sig[3] = op(a3, b3); \
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r->sig[2] = op(a2, b2); \
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case 2: \
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a1 = a->sig[1]; b1 = b->sig[1]; \
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r->sig[1] = op(a1, b1); \
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case 1: \
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a0 = a->sig[0]; b0 = b->sig[0]; \
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r->sig[0] = op(a0, b0); \
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break; \
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default: \
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_NSIG_WORDS_is_unsupported_size(); \
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} \
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}
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#define _sig_or(x,y) ((x) | (y))
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_SIG_SET_BINOP(sigorsets, _sig_or)
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#define _sig_and(x,y) ((x) & (y))
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_SIG_SET_BINOP(sigandsets, _sig_and)
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#define _sig_nand(x,y) ((x) & ~(y))
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_SIG_SET_BINOP(signandsets, _sig_nand)
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#undef _SIG_SET_BINOP
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#undef _sig_or
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#undef _sig_and
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#undef _sig_nand
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#define _SIG_SET_OP(name, op) \
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static inline void name(sigset_t *set) \
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{ \
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extern void _NSIG_WORDS_is_unsupported_size(void); \
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\
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switch (_NSIG_WORDS) { \
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case 4: set->sig[3] = op(set->sig[3]); \
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set->sig[2] = op(set->sig[2]); \
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case 2: set->sig[1] = op(set->sig[1]); \
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case 1: set->sig[0] = op(set->sig[0]); \
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break; \
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default: \
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_NSIG_WORDS_is_unsupported_size(); \
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} \
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}
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#define _sig_not(x) (~(x))
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_SIG_SET_OP(signotset, _sig_not)
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#undef _SIG_SET_OP
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#undef _sig_not
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static inline void sigemptyset(sigset_t *set)
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{
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switch (_NSIG_WORDS) {
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default:
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memset(set, 0, sizeof(sigset_t));
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break;
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case 2: set->sig[1] = 0;
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case 1: set->sig[0] = 0;
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break;
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}
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}
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static inline void sigfillset(sigset_t *set)
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{
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switch (_NSIG_WORDS) {
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default:
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memset(set, -1, sizeof(sigset_t));
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break;
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case 2: set->sig[1] = -1;
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case 1: set->sig[0] = -1;
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break;
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}
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}
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/* Some extensions for manipulating the low 32 signals in particular. */
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static inline void sigaddsetmask(sigset_t *set, unsigned long mask)
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{
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set->sig[0] |= mask;
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}
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static inline void sigdelsetmask(sigset_t *set, unsigned long mask)
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{
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set->sig[0] &= ~mask;
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}
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static inline int sigtestsetmask(sigset_t *set, unsigned long mask)
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{
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return (set->sig[0] & mask) != 0;
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}
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static inline void siginitset(sigset_t *set, unsigned long mask)
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{
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set->sig[0] = mask;
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switch (_NSIG_WORDS) {
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default:
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memset(&set->sig[1], 0, sizeof(long)*(_NSIG_WORDS-1));
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break;
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case 2: set->sig[1] = 0;
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case 1: ;
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}
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}
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static inline void siginitsetinv(sigset_t *set, unsigned long mask)
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{
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set->sig[0] = ~mask;
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switch (_NSIG_WORDS) {
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default:
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memset(&set->sig[1], -1, sizeof(long)*(_NSIG_WORDS-1));
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break;
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case 2: set->sig[1] = -1;
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case 1: ;
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}
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}
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#endif /* __HAVE_ARCH_SIG_SETOPS */
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static inline void init_sigpending(struct sigpending *sig)
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{
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sigemptyset(&sig->signal);
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INIT_LIST_HEAD(&sig->list);
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}
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extern void flush_sigqueue(struct sigpending *queue);
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/* Test if 'sig' is valid signal. Use this instead of testing _NSIG directly */
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static inline int valid_signal(unsigned long sig)
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{
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return sig <= _NSIG ? 1 : 0;
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}
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extern int next_signal(struct sigpending *pending, sigset_t *mask);
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extern int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p);
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extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *);
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extern long do_sigpending(void __user *, unsigned long);
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extern int sigprocmask(int, sigset_t *, sigset_t *);
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extern int show_unhandled_signals;
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struct pt_regs;
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extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie);
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extern struct kmem_cache *sighand_cachep;
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int unhandled_signal(struct task_struct *tsk, int sig);
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/*
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* In POSIX a signal is sent either to a specific thread (Linux task)
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* or to the process as a whole (Linux thread group). How the signal
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* is sent determines whether it's to one thread or the whole group,
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* which determines which signal mask(s) are involved in blocking it
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* from being delivered until later. When the signal is delivered,
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* either it's caught or ignored by a user handler or it has a default
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* effect that applies to the whole thread group (POSIX process).
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*
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* The possible effects an unblocked signal set to SIG_DFL can have are:
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* ignore - Nothing Happens
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* terminate - kill the process, i.e. all threads in the group,
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* similar to exit_group. The group leader (only) reports
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* WIFSIGNALED status to its parent.
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* coredump - write a core dump file describing all threads using
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* the same mm and then kill all those threads
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* stop - stop all the threads in the group, i.e. TASK_STOPPED state
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*
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* SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
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* Other signals when not blocked and set to SIG_DFL behaves as follows.
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* The job control signals also have other special effects.
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*
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* +--------------------+------------------+
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* | POSIX signal | default action |
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* +--------------------+------------------+
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* | SIGHUP | terminate |
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* | SIGINT | terminate |
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* | SIGQUIT | coredump |
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* | SIGILL | coredump |
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* | SIGTRAP | coredump |
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* | SIGABRT/SIGIOT | coredump |
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* | SIGBUS | coredump |
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* | SIGFPE | coredump |
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* | SIGKILL | terminate(+) |
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* | SIGUSR1 | terminate |
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* | SIGSEGV | coredump |
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* | SIGUSR2 | terminate |
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* | SIGPIPE | terminate |
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* | SIGALRM | terminate |
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* | SIGTERM | terminate |
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* | SIGCHLD | ignore |
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* | SIGCONT | ignore(*) |
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* | SIGSTOP | stop(*)(+) |
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* | SIGTSTP | stop(*) |
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* | SIGTTIN | stop(*) |
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* | SIGTTOU | stop(*) |
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* | SIGURG | ignore |
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* | SIGXCPU | coredump |
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* | SIGXFSZ | coredump |
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* | SIGVTALRM | terminate |
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* | SIGPROF | terminate |
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* | SIGPOLL/SIGIO | terminate |
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* | SIGSYS/SIGUNUSED | coredump |
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* | SIGSTKFLT | terminate |
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* | SIGWINCH | ignore |
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* | SIGPWR | terminate |
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* | SIGRTMIN-SIGRTMAX | terminate |
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* +--------------------+------------------+
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* | non-POSIX signal | default action |
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* +--------------------+------------------+
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* | SIGEMT | coredump |
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* +--------------------+------------------+
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*
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* (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
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* (*) Special job control effects:
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* When SIGCONT is sent, it resumes the process (all threads in the group)
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* from TASK_STOPPED state and also clears any pending/queued stop signals
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* (any of those marked with "stop(*)"). This happens regardless of blocking,
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* catching, or ignoring SIGCONT. When any stop signal is sent, it clears
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* any pending/queued SIGCONT signals; this happens regardless of blocking,
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* catching, or ignored the stop signal, though (except for SIGSTOP) the
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* default action of stopping the process may happen later or never.
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*/
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#ifdef SIGEMT
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#define SIGEMT_MASK rt_sigmask(SIGEMT)
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#else
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#define SIGEMT_MASK 0
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#endif
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#if SIGRTMIN > BITS_PER_LONG
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#define rt_sigmask(sig) (1ULL << ((sig)-1))
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#else
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#define rt_sigmask(sig) sigmask(sig)
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#endif
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#define siginmask(sig, mask) (rt_sigmask(sig) & (mask))
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#define SIG_KERNEL_ONLY_MASK (\
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rt_sigmask(SIGKILL) | rt_sigmask(SIGSTOP))
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#define SIG_KERNEL_STOP_MASK (\
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rt_sigmask(SIGSTOP) | rt_sigmask(SIGTSTP) | \
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rt_sigmask(SIGTTIN) | rt_sigmask(SIGTTOU) )
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#define SIG_KERNEL_COREDUMP_MASK (\
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rt_sigmask(SIGQUIT) | rt_sigmask(SIGILL) | \
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rt_sigmask(SIGTRAP) | rt_sigmask(SIGABRT) | \
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rt_sigmask(SIGFPE) | rt_sigmask(SIGSEGV) | \
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rt_sigmask(SIGBUS) | rt_sigmask(SIGSYS) | \
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rt_sigmask(SIGXCPU) | rt_sigmask(SIGXFSZ) | \
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SIGEMT_MASK )
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#define SIG_KERNEL_IGNORE_MASK (\
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rt_sigmask(SIGCONT) | rt_sigmask(SIGCHLD) | \
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rt_sigmask(SIGWINCH) | rt_sigmask(SIGURG) )
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#define sig_kernel_only(sig) \
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(((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_ONLY_MASK))
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#define sig_kernel_coredump(sig) \
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(((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_COREDUMP_MASK))
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#define sig_kernel_ignore(sig) \
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(((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_IGNORE_MASK))
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#define sig_kernel_stop(sig) \
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(((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_STOP_MASK))
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#define sig_needs_tasklist(sig) ((sig) == SIGCONT)
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#define sig_user_defined(t, signr) \
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(((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
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((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
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#define sig_fatal(t, signr) \
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(!siginmask(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
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(t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
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#endif /* __KERNEL__ */
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#endif /* _LINUX_SIGNAL_H */
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