From: "Jan Beulich" <jbeulich@novell.com>
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>
Signed-off-by: Andi Kleen <ak@suse.de>
arch/x86_64/kernel/mce.c | 7 ++++---
arch/x86_64/kernel/traps.c | 23 +++++++++++++++--------
arch/x86_64/mm/fault.c | 12 ++++++------
include/asm-x86_64/kdebug.h | 4 ++--
4 files changed, 27 insertions(+), 19 deletions(-)
Index: linux/arch/x86_64/kernel/mce.c
===================================================================
--- linux.orig/arch/x86_64/kernel/mce.c
+++ linux/arch/x86_64/kernel/mce.c
@@ -196,9 +196,10 @@ void do_machine_check(struct pt_regs * r
atomic_inc(&mce_entry);
- if (regs)
- notify_die(DIE_NMI, "machine check", regs, error_code, 18, SIGKILL);
- if (!banks)
+ if ((regs
+ && notify_die(DIE_NMI, "machine check", regs, error_code,
+ 18, SIGKILL) == NOTIFY_STOP)
+ || !banks)
goto out2;
memset(&m, 0, sizeof(struct mce));
Index: linux/arch/x86_64/kernel/traps.c
===================================================================
--- linux.orig/arch/x86_64/kernel/traps.c
+++ linux/arch/x86_64/kernel/traps.c
@@ -557,7 +557,7 @@ unsigned __kprobes long oops_begin(void)
return flags;
}
-void __kprobes oops_end(unsigned long flags)
+void __kprobes oops_end(unsigned long flags, struct pt_regs *regs, int signr)
{
die_owner = -1;
bust_spinlocks(0);
@@ -568,12 +568,17 @@ void __kprobes oops_end(unsigned long fl
else
/* Nest count reaches zero, release the lock. */
spin_unlock_irqrestore(&die_lock, flags);
+ if (!regs) {
+ oops_exit();
+ return;
+ }
if (panic_on_oops)
panic("Fatal exception");
oops_exit();
+ do_exit(signr);
}
-void __kprobes __die(const char * str, struct pt_regs * regs, long err)
+int __kprobes __die(const char * str, struct pt_regs * regs, long err)
{
static int die_counter;
printk(KERN_EMERG "%s: %04lx [%u] ", str, err & 0xffff,++die_counter);
@@ -587,7 +592,8 @@ void __kprobes __die(const char * str, s
printk("DEBUG_PAGEALLOC");
#endif
printk("\n");
- notify_die(DIE_OOPS, str, regs, err, current->thread.trap_no, SIGSEGV);
+ if (notify_die(DIE_OOPS, str, regs, err, current->thread.trap_no, SIGSEGV) == NOTIFY_STOP)
+ return 1;
show_registers(regs);
add_taint(TAINT_DIE);
/* Executive summary in case the oops scrolled away */
@@ -596,6 +602,7 @@ void __kprobes __die(const char * str, s
printk(" RSP <%016lx>\n", regs->rsp);
if (kexec_should_crash(current))
crash_kexec(regs);
+ return 0;
}
void die(const char * str, struct pt_regs * regs, long err)
@@ -605,9 +612,9 @@ void die(const char * str, struct pt_reg
if (!user_mode(regs))
report_bug(regs->rip, regs);
- __die(str, regs, err);
- oops_end(flags);
- do_exit(SIGSEGV);
+ if (__die(str, regs, err))
+ regs = NULL;
+ oops_end(flags, regs, SIGSEGV);
}
void __kprobes die_nmi(char *str, struct pt_regs *regs, int do_panic)
@@ -624,10 +631,10 @@ void __kprobes die_nmi(char *str, struct
crash_kexec(regs);
if (do_panic || panic_on_oops)
panic("Non maskable interrupt");
- oops_end(flags);
+ oops_end(flags, NULL, SIGBUS);
nmi_exit();
local_irq_enable();
- do_exit(SIGSEGV);
+ do_exit(SIGBUS);
}
static void __kprobes do_trap(int trapnr, int signr, char *str,
Index: linux/arch/x86_64/mm/fault.c
===================================================================
--- linux.orig/arch/x86_64/mm/fault.c
+++ linux/arch/x86_64/mm/fault.c
@@ -234,9 +234,9 @@ static noinline void pgtable_bad(unsigne
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
- __die("Bad pagetable", regs, error_code);
- oops_end(flags);
- do_exit(SIGKILL);
+ if (__die("Bad pagetable", regs, error_code))
+ regs = NULL;
+ oops_end(flags, regs, SIGKILL);
}
/*
@@ -541,11 +541,11 @@ no_context:
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
tsk->thread.error_code = error_code;
- __die("Oops", regs, error_code);
+ if (__die("Oops", regs, error_code))
+ regs = NULL;
/* Executive summary in case the body of the oops scrolled away */
printk(KERN_EMERG "CR2: %016lx\n", address);
- oops_end(flags);
- do_exit(SIGKILL);
+ oops_end(flags, regs, SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
Index: linux/include/asm-x86_64/kdebug.h
===================================================================
--- linux.orig/include/asm-x86_64/kdebug.h
+++ linux/include/asm-x86_64/kdebug.h
@@ -27,10 +27,10 @@ enum die_val {
extern void printk_address(unsigned long address);
extern void die(const char *,struct pt_regs *,long);
-extern void __die(const char *,struct pt_regs *,long);
+extern int __must_check __die(const char *, struct pt_regs *, long);
extern void show_registers(struct pt_regs *regs);
extern void dump_pagetable(unsigned long);
extern unsigned long oops_begin(void);
-extern void oops_end(unsigned long);
+extern void oops_end(unsigned long, struct pt_regs *, int signr);
#endif
-
