[PATCH] honor notify_die() returning NOTIFY_STOP

Jan Beulich
2007-08-28T09:58:46Z

If a debugger or other low level code resolves a kernel exception, don't
send signals, kill the kernel, or do anything the like.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

arch/ia64/ia32/ia32_support.c | 5 +++--
arch/ia64/kernel/traps.c | 35 +++++++++++++++++++++++------------
arch/ia64/kernel/unaligned.c | 13 ++++++++-----
arch/ia64/mm/fault.c | 8 +++++---
4 files changed, 39 insertions(+), 22 deletions(-)

--- linux-2.6.23-rc4/arch/ia64/ia32/ia32_support.c 2007-08-28 10:10:06.000000000 +0200
+++ 2.6.23-rc4-ia64-notify-die-return/arch/ia64/ia32/ia32_support.c 2007-08-22 13:49:10.000000000 +0200
@@ -27,7 +27,7 @@

#include "ia32priv.h"

-extern void die_if_kernel (char *str, struct pt_regs *regs, long err);
+extern int die_if_kernel (char *str, struct pt_regs *regs, long err);

struct exec_domain ia32_exec_domain;
struct page *ia32_shared_page[NR_CPUS];
@@ -217,7 +217,8 @@ ia32_bad_interrupt (unsigned long int_nu
{
siginfo_t siginfo;

- die_if_kernel("Bad IA-32 interrupt", regs, int_num);
+ if (die_if_kernel("Bad IA-32 interrupt", regs, int_num))
+ return;

siginfo.si_signo = SIGTRAP;
siginfo.si_errno = int_num; /* XXX is it OK to abuse si_errno like this? */
--- linux-2.6.23-rc4/arch/ia64/kernel/traps.c 2007-08-28 10:10:06.000000000 +0200
+++ 2.6.23-rc4-ia64-notify-die-return/arch/ia64/kernel/traps.c 2007-08-22 13:59:40.000000000 +0200
@@ -35,7 +35,7 @@ trap_init (void)
fpswa_interface = __va(ia64_boot_param->fpswa);
}

-void
+int
die (const char *str, struct pt_regs *regs, long err)
{
static struct {
@@ -62,8 +62,11 @@ die (const char *str, struct pt_regs *re
if (++die.lock_owner_depth < 3) {
printk("%s[%d]: %s %ld [%d]\n",
current->comm, current->pid, str, err, ++die_counter);
- (void) notify_die(DIE_OOPS, (char *)str, regs, err, 255, SIGSEGV);
- show_regs(regs);
+ if (notify_die(DIE_OOPS, (char *)str, regs, err, 255, SIGSEGV)
+ != NOTIFY_STOP)
+ show_regs(regs);
+ else
+ regs = NULL;
} else
printk(KERN_ERR "Recursive die() failure, output suppressed\n");

@@ -72,17 +75,22 @@ die (const char *str, struct pt_regs *re
add_taint(TAINT_DIE);
spin_unlock_irq(&die.lock);

+ if (!regs)
+ return 1;
+
if (panic_on_oops)
panic("Fatal exception");

do_exit(SIGSEGV);
+ return 0;
}

-void
+int
die_if_kernel (char *str, struct pt_regs *regs, long err)
{
if (!user_mode(regs))
- die(str, regs, err);
+ return die(str, regs, err);
+ return 0;
}

void
@@ -102,7 +110,8 @@ __kprobes ia64_bad_break (unsigned long
if (notify_die(DIE_BREAK, "break 0", regs, break_num, TRAP_BRKPT, SIGTRAP)
= NOTIFY_STOP)
return;
- die_if_kernel("bugcheck!", regs, break_num);
+ if (die_if_kernel("bugcheck!", regs, break_num))
+ return;
sig = SIGILL; code = ILL_ILLOPC;
break;

@@ -155,8 +164,9 @@ __kprobes ia64_bad_break (unsigned long
break;

default:
- if (break_num < 0x40000 || break_num > 0x100000)
- die_if_kernel("Bad break", regs, break_num);
+ if ((break_num < 0x40000 || break_num > 0x100000)
+ && die_if_kernel("Bad break", regs, break_num))
+ return;

if (break_num < 0x80000) {
sig = SIGILL; code = __ILL_BREAK;
@@ -402,14 +412,15 @@ ia64_illegal_op_fault (unsigned long ec,
#endif

sprintf(buf, "IA-64 Illegal operation fault");
- die_if_kernel(buf, &regs, 0);
+ rv.fkt = 0;
+ if (die_if_kernel(buf, &regs, 0))
+ return rv;

memset(&si, 0, sizeof(si));
si.si_signo = SIGILL;
si.si_code = ILL_ILLOPC;
si.si_addr = (void __user *) (regs.cr_iip + ia64_psr(&regs)->ri);
force_sig_info(SIGILL, &si, current);
- rv.fkt = 0;
return rv;
}

@@ -644,6 +655,6 @@ ia64_fault (unsigned long vector, unsign
sprintf(buf, "Fault %lu", vector);
break;
}
- die_if_kernel(buf, &regs, error);
- force_sig(SIGILL, current);
+ if (!die_if_kernel(buf, &regs, error))
+ force_sig(SIGILL, current);
}
--- linux-2.6.23-rc4/arch/ia64/kernel/unaligned.c 2007-07-09 01:32:17.000000000 +0200
+++ 2.6.23-rc4-ia64-notify-die-return/arch/ia64/kernel/unaligned.c 2007-08-22 13:53:35.000000000 +0200
@@ -23,7 +23,7 @@
#include <asm/uaccess.h>
#include <asm/unaligned.h>

-extern void die_if_kernel(char *str, struct pt_regs *regs, long err);
+extern int die_if_kernel(char *str, struct pt_regs *regs, long err);

#undef DEBUG_UNALIGNED_TRAP

@@ -675,8 +675,9 @@ emulate_load_updates (update_t type, loa
*/
if (ld.x6_op = 1 || ld.x6_op = 3) {
printk(KERN_ERR "%s: register update on speculative load, error\n", __FUNCTION__);
- die_if_kernel("unaligned reference on speculative load with register update\n",
- regs, 30);
+ if (die_if_kernel("unaligned reference on speculative load with register update\n",
+ regs, 30))
+ return;
}

@@ -1317,7 +1318,8 @@ ia64_handle_unaligned (unsigned long ifa

if (ia64_psr(regs)->be) {
/* we don't support big-endian accesses */
- die_if_kernel("big-endian unaligned accesses are not supported", regs, 0);
+ if (die_if_kernel("big-endian unaligned accesses are not supported", regs, 0))
+ return;
goto force_sigbus;
}

@@ -1530,7 +1532,8 @@ ia64_handle_unaligned (unsigned long ifa
ia64_handle_exception(regs, eh);
goto done;
}
- die_if_kernel("error during unaligned kernel access\n", regs, ret);
+ if (die_if_kernel("error during unaligned kernel access\n", regs, ret))
+ return;
/* NOT_REACHED */
}
force_sigbus:
--- linux-2.6.23-rc4/arch/ia64/mm/fault.c 2007-08-28 10:10:06.000000000 +0200
+++ 2.6.23-rc4-ia64-notify-die-return/arch/ia64/mm/fault.c 2007-08-22 13:50:08.000000000 +0200
@@ -16,7 +16,7 @@
#include <asm/system.h>
#include <asm/uaccess.h>

-extern void die (char *, struct pt_regs *, long);
+extern int die(char *, struct pt_regs *, long);

#ifdef CONFIG_KPROBES
static inline int notify_page_fault(struct pt_regs *regs, int trap)
@@ -267,9 +267,11 @@ ia64_do_page_fault (unsigned long addres
else
printk(KERN_ALERT "Unable to handle kernel paging request at "
"virtual address %016lx\n", address);
- die("Oops", regs, isr);
+ if (die("Oops", regs, isr))
+ regs = NULL;
bust_spinlocks(0);
- do_exit(SIGKILL);
+ if (regs)
+ do_exit(SIGKILL);
return;