x86, dumpstack: let signr=0 signal no do_exit

Change oops_end such that signr=0 signals that do_exit
is not to be called.

Currently, each use of __die is soon followed by a call
to oops_end and 'regs' is set to NULL if oops_end is expected
not to call do_exit. Change all such pairs to set signr=0
instead. On x86_64 oops_end is used 'bare' in die_nmi; use
signr=0 instead of regs=NULL there, too.

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 16 insertions, 11 deletions

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index 5493d31be4e5..7c22f99f0efb 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -318,7 +318,7 @@ void __kprobes oops_end(unsigned long flags, struct pt_regs *regs, int signr)
         __raw_spin_unlock(&die_lock);
         raw_local_irq_restore(flags);
 
-        if (!regs)
+        if (!signr)
                 return;
 
         if (in_interrupt())
@@ -371,17 +371,18 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err)
 void die(const char *str, struct pt_regs *regs, long err)
 {
         unsigned long flags = oops_begin();
+        int sig = SIGSEGV;
 
         if (die_nest_count < 3) {
                 report_bug(regs->ip, regs);
 
                 if (__die(str, regs, err))
-                        regs = NULL;
+                        sig = 0;
         } else {
                 printk(KERN_EMERG "Recursive die() failure, output suppressed\n");
         }
 
-        oops_end(flags, regs, SIGSEGV);
+        oops_end(flags, regs, sig);
 }
 
 static DEFINE_SPINLOCK(nmi_print_lock);
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 96a5db7da8a7..ffefea611ba3 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -465,7 +465,7 @@ void __kprobes oops_end(unsigned long flags, struct pt_regs *regs, int signr)
                 /* Nest count reaches zero, release the lock. */
                 __raw_spin_unlock(&die_lock);
         raw_local_irq_restore(flags);
-        if (!regs) {
+        if (!signr) {
                 oops_exit();
                 return;
         }
@@ -509,13 +509,14 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err)
 void die(const char *str, struct pt_regs *regs, long err)
 {
         unsigned long flags = oops_begin();
+        int sig = SIGSEGV;
 
         if (!user_mode(regs))
                 report_bug(regs->ip, regs);
 
         if (__die(str, regs, err))
-                regs = NULL;
-        oops_end(flags, regs, SIGSEGV);
+                sig = 0;
+        oops_end(flags, regs, sig);
 }
 
 notrace __kprobes void
@@ -539,7 +540,7 @@ die_nmi(char *str, struct pt_regs *regs, int do_panic)
                 crash_kexec(regs);
         if (do_panic || panic_on_oops)
                 panic("Non maskable interrupt");
-        oops_end(flags, NULL, SIGBUS);
+        oops_end(flags, regs, 0);
         nmi_exit();
         local_irq_enable();
         do_exit(SIGBUS);
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 31e8730fa246..20ef272c412c 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -413,6 +413,7 @@ static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
                                  unsigned long error_code)
 {
         unsigned long flags = oops_begin();
+        int sig = SIGKILL;
         struct task_struct *tsk;
 
         printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
@@ -423,8 +424,8 @@ static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
         tsk->thread.trap_no = 14;
         tsk->thread.error_code = error_code;
         if (__die("Bad pagetable", regs, error_code))
-                regs = NULL;
-        oops_end(flags, regs, SIGKILL);
+                sig = 0;
+        oops_end(flags, regs, sig);
 }
 #endif
 
@@ -590,6 +591,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
         int fault;
 #ifdef CONFIG_X86_64
         unsigned long flags;
+        int sig;
 #endif
 
         tsk = current;
@@ -849,11 +851,12 @@ no_context:
         bust_spinlocks(0);
         do_exit(SIGKILL);
 #else
+        sig = SIGKILL;
         if (__die("Oops", regs, error_code))
-                regs = NULL;
+                sig = 0;
         /* Executive summary in case the body of the oops scrolled away */
         printk(KERN_EMERG "CR2: %016lx\n", address);
-        oops_end(flags, regs, SIGKILL);
+        oops_end(flags, regs, sig);
 #endif
 
 /*