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Commit d0c3d534 authored by Olof Johansson's avatar Olof Johansson Committed by Paul Mackerras
Browse files

[POWERPC] Implement logging of unhandled signals 



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: default avatarOlof Johansson <olof@lixom.net>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent b63db45c

arch/powerpc/kernel/signal.c

+6 −0
Original line number Diff line number Diff line
@@ -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

 */

arch/powerpc/kernel/signal_32.c

+38 −0
Original line number Diff line number Diff line
@@ -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;
@@ -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;
@@ -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;
@@ -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;

}
@@ -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;

}
@@ -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;

	}
@@ -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;

}
@@ -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;
@@ -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;
@@ -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;

}

arch/powerpc/kernel/signal_64.c

+15 −0
Original line number Diff line number Diff line
@@ -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.

 */
@@ -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;

}
@@ -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;

}

arch/powerpc/kernel/traps.c

+11 −1
Original line number Diff line number Diff line
@@ -172,10 +172,20 @@ 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));

kernel/sysctl.c

+1 −1
Original line number Diff line number Diff line
@@ -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",