Re: [PATCH 2/7] x86, dumpstack: let signr=0 signal no do_exit

Neil Horman
2008-10-22T11:03:48Z

On Wed, Oct 22, 2008 at 12:00:09PM +0200, Alexander van Heukelum wrote:
> 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>

> ---
> arch/x86/kernel/dumpstack_32.c | 7 ++++---
> arch/x86/kernel/dumpstack_64.c | 9 +++++----
> arch/x86/mm/fault.c | 11 +++++++----
> 3 files changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
> index 5493d31..7c22f99 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 96a5db7..ffefea6 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 8e52e68..ed9ee30 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -415,6 +415,7 @@ 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",
> @@ -425,8 +426,8 @@ 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
>
> @@ -594,6 +595,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
>
> #ifdef CONFIG_X86_64
> unsigned long flags;
> + int sig;
> #endif
>
> tsk = current;
> @@ -868,11 +870,12 @@ 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
>
> /*
> --
> 1.5.4.3
>
>

--
/****************************************************
* Neil Horman <nhorman@tuxdriver.com>
* Software Engineer, Red Hat
****************************************************/