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[POWERPC] Implement logging of unhandled signals
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Implement show_unhandled_signals sysctl + support to print when a process
is killed due to unhandled signals just as i386 and x86_64 does.

Default to having it off, unlike x86 that defaults on.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Olof Johansson authored and Paul Mackerras committed Oct 12, 2007
1 parent b63db45 commit d0c3d53
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Showing 5 changed files with 71 additions and 2 deletions.
6 changes: 6 additions & 0 deletions arch/powerpc/kernel/signal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,12 @@

#include "signal.h"

/* Log an error when sending an unhandled signal to a process. Controlled
* through debug.exception-trace sysctl.
*/

int show_unhandled_signals = 0;

/*
* Allocate space for the signal frame
*/
Expand Down
38 changes: 38 additions & 0 deletions arch/powerpc/kernel/signal_32.c
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Original file line number Diff line number Diff line change
Expand Up @@ -705,11 +705,13 @@ int handle_rt_signal32(unsigned long sig, struct k_sigaction *ka,
{
struct rt_sigframe __user *rt_sf;
struct mcontext __user *frame;
void __user *addr;
unsigned long newsp = 0;

/* Set up Signal Frame */
/* Put a Real Time Context onto stack */
rt_sf = get_sigframe(ka, regs, sizeof(*rt_sf));
addr = rt_sf;
if (unlikely(rt_sf == NULL))
goto badframe;

Expand All @@ -728,6 +730,7 @@ int handle_rt_signal32(unsigned long sig, struct k_sigaction *ka,

/* Save user registers on the stack */
frame = &rt_sf->uc.uc_mcontext;
addr = frame;
if (vdso32_rt_sigtramp && current->mm->context.vdso_base) {
if (save_user_regs(regs, frame, 0))
goto badframe;
Expand All @@ -742,6 +745,7 @@ int handle_rt_signal32(unsigned long sig, struct k_sigaction *ka,

/* create a stack frame for the caller of the handler */
newsp = ((unsigned long)rt_sf) - (__SIGNAL_FRAMESIZE + 16);
addr = (void __user *)regs->gpr[1];
if (put_user(regs->gpr[1], (u32 __user *)newsp))
goto badframe;

Expand All @@ -762,6 +766,12 @@ int handle_rt_signal32(unsigned long sig, struct k_sigaction *ka,
printk("badframe in handle_rt_signal, regs=%p frame=%p newsp=%lx\n",
regs, frame, newsp);
#endif
if (show_unhandled_signals && printk_ratelimit())
printk(KERN_INFO "%s[%d]: bad frame in handle_rt_signal32: "
"%p nip %08lx lr %08lx\n",
current->comm, current->pid,
addr, regs->nip, regs->link);

force_sigsegv(sig, current);
return 0;
}
Expand Down Expand Up @@ -886,6 +896,12 @@ long sys_rt_sigreturn(int r3, int r4, int r5, int r6, int r7, int r8,
return 0;

bad:
if (show_unhandled_signals && printk_ratelimit())
printk(KERN_INFO "%s[%d]: bad frame in sys_rt_sigreturn: "
"%p nip %08lx lr %08lx\n",
current->comm, current->pid,
rt_sf, regs->nip, regs->link);

force_sig(SIGSEGV, current);
return 0;
}
Expand Down Expand Up @@ -967,6 +983,13 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
* We kill the task with a SIGSEGV in this situation.
*/
if (do_setcontext(ctx, regs, 1)) {
if (show_unhandled_signals && printk_ratelimit())
printk(KERN_INFO "%s[%d]: bad frame in "
"sys_debug_setcontext: %p nip %08lx "
"lr %08lx\n",
current->comm, current->pid,
ctx, regs->nip, regs->link);

force_sig(SIGSEGV, current);
goto out;
}
Expand Down Expand Up @@ -1048,6 +1071,12 @@ int handle_signal32(unsigned long sig, struct k_sigaction *ka,
printk("badframe in handle_signal, regs=%p frame=%p newsp=%lx\n",
regs, frame, newsp);
#endif
if (show_unhandled_signals && printk_ratelimit())
printk(KERN_INFO "%s[%d]: bad frame in handle_signal32: "
"%p nip %08lx lr %08lx\n",
current->comm, current->pid,
frame, regs->nip, regs->link);

force_sigsegv(sig, current);
return 0;
}
Expand All @@ -1061,12 +1090,14 @@ long sys_sigreturn(int r3, int r4, int r5, int r6, int r7, int r8,
struct sigcontext __user *sc;
struct sigcontext sigctx;
struct mcontext __user *sr;
void __user *addr;
sigset_t set;

/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;

sc = (struct sigcontext __user *)(regs->gpr[1] + __SIGNAL_FRAMESIZE);
addr = sc;
if (copy_from_user(&sigctx, sc, sizeof(sigctx)))
goto badframe;

Expand All @@ -1083,6 +1114,7 @@ long sys_sigreturn(int r3, int r4, int r5, int r6, int r7, int r8,
restore_sigmask(&set);

sr = (struct mcontext __user *)from_user_ptr(sigctx.regs);
addr = sr;
if (!access_ok(VERIFY_READ, sr, sizeof(*sr))
|| restore_user_regs(regs, sr, 1))
goto badframe;
Expand All @@ -1091,6 +1123,12 @@ long sys_sigreturn(int r3, int r4, int r5, int r6, int r7, int r8,
return 0;

badframe:
if (show_unhandled_signals && printk_ratelimit())
printk(KERN_INFO "%s[%d]: bad frame in sys_sigreturn: "
"%p nip %08lx lr %08lx\n",
current->comm, current->pid,
addr, regs->nip, regs->link);

force_sig(SIGSEGV, current);
return 0;
}
15 changes: 15 additions & 0 deletions arch/powerpc/kernel/signal_64.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,11 @@ struct rt_sigframe {
char abigap[288];
} __attribute__ ((aligned (16)));

static const char fmt32[] = KERN_INFO \
"%s[%d]: bad frame in %s: %08lx nip %08lx lr %08lx\n";
static const char fmt64[] = KERN_INFO \
"%s[%d]: bad frame in %s: %016lx nip %016lx lr %016lx\n";

/*
* Set up the sigcontext for the signal frame.
*/
Expand Down Expand Up @@ -315,6 +320,11 @@ int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n",
regs, uc, &uc->uc_mcontext);
#endif
if (show_unhandled_signals && printk_ratelimit())
printk(regs->msr & MSR_SF ? fmt64 : fmt32,
current->comm, current->pid, "rt_sigreturn",
(long)uc, regs->nip, regs->link);

force_sig(SIGSEGV, current);
return 0;
}
Expand Down Expand Up @@ -398,6 +408,11 @@ int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info,
printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
regs, frame, newsp);
#endif
if (show_unhandled_signals && printk_ratelimit())
printk(regs->msr & MSR_SF ? fmt64 : fmt32,
current->comm, current->pid, "setup_rt_frame",
(long)frame, regs->nip, regs->link);

force_sigsegv(signr, current);
return 0;
}
12 changes: 11 additions & 1 deletion arch/powerpc/kernel/traps.c
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Original file line number Diff line number Diff line change
Expand Up @@ -172,11 +172,21 @@ int die(const char *str, struct pt_regs *regs, long err)
void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
{
siginfo_t info;
const char fmt32[] = KERN_INFO "%s[%d]: unhandled signal %d " \
"at %08lx nip %08lx lr %08lx code %x\n";
const char fmt64[] = KERN_INFO "%s[%d]: unhandled signal %d " \
"at %016lx nip %016lx lr %016lx code %x\n";

if (!user_mode(regs)) {
if (die("Exception in kernel mode", regs, signr))
return;
}
} else if (show_unhandled_signals &&
unhandled_signal(current, signr) &&
printk_ratelimit()) {
printk(regs->msr & MSR_SF ? fmt64 : fmt32,
current->comm, current->pid, signr,
addr, regs->nip, regs->link, code);
}

memset(&info, 0, sizeof(info));
info.si_signo = signr;
Expand Down
2 changes: 1 addition & 1 deletion kernel/sysctl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1221,7 +1221,7 @@ static ctl_table fs_table[] = {
};

static ctl_table debug_table[] = {
#ifdef CONFIG_X86
#if defined(CONFIG_X86) || defined(CONFIG_PPC)
{
.ctl_name = CTL_UNNUMBERED,
.procname = "exception-trace",
Expand Down

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