Re: [1/4] Exceptions Notifier patch

Prasanna S Panchamukhi
2004-08-12T12:25:35Z

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Hi Andi,

On Wed, Aug 11, 2004 at 06:36:16PM +0200, Andi Kleen wrote:
> Prasanna S Panchamukhi <prasanna@in.ibm.com> writes:
>
> Just some cosmetical comments.
>
> >
> > +EXPORT_SYMBOL(register_die_chain_notify);
>
> Please name it "register_die_notifier"
>
> >
> > static int kstack_depth_to_print = 24;
> > +struct notifier_block *i386die_chain;
> > +static DECLARE_MUTEX(i386die_chain_mutex);
>
> s/i386//
>
> I don't know why you made this a mutex, a spinlock would
> be fine too. But that's a minor issue.
>

I have modified the patch as per your comments.

Please let me know if you any issues.

Thanks
Prasanna
--

Prasanna S Panchamukhi
Linux Technology Center
India Software Labs, IBM Bangalore
Ph: 91-80-25044636
<prasanna@in.ibm.com>

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This patch provides notifiers for i386 architecture exceptions. This
patch has been ported from x86_64 architecture as suggested by Andi Kleen.

---

---

---

linux-2.6.8-rc4-prasanna/arch/i386/kernel/i386_ksyms.c | 2
linux-2.6.8-rc4-prasanna/arch/i386/kernel/traps.c | 40 +++++++++++++
linux-2.6.8-rc4-prasanna/arch/i386/mm/fault.c | 4 +
linux-2.6.8-rc4-prasanna/include/asm-i386/kdebug.h | 50 +++++++++++++++++
4 files changed, 95 insertions(+), 1 deletion(-)

diff -puN arch/i386/kernel/i386_ksyms.c~i386_exception_notifiers-268-rc4 arch/i386/kernel/i386_ksyms.c
--- linux-2.6.8-rc4/arch/i386/kernel/i386_ksyms.c~i386_exception_notifiers-268-rc4 2004-08-12 17:08:48.000000000 +0530
+++ linux-2.6.8-rc4-prasanna/arch/i386/kernel/i386_ksyms.c 2004-08-12 17:08:48.000000000 +0530
@@ -32,6 +32,7 @@
#include <asm/tlbflush.h>
#include <asm/nmi.h>
#include <asm/ist.h>
+#include <asm/kdebug.h>

extern void dump_thread(struct pt_regs *, struct user *);
extern spinlock_t rtc_lock;
@@ -177,6 +178,7 @@ EXPORT_SYMBOL_GPL(unset_nmi_callback);
extern int memcmp(const void *,const void *,__kernel_size_t);
EXPORT_SYMBOL_NOVERS(memcmp);

+EXPORT_SYMBOL(register_die_notifier);
#ifdef CONFIG_HAVE_DEC_LOCK
EXPORT_SYMBOL(atomic_dec_and_lock);
#endif
diff -puN arch/i386/kernel/traps.c~i386_exception_notifiers-268-rc4 arch/i386/kernel/traps.c
--- linux-2.6.8-rc4/arch/i386/kernel/traps.c~i386_exception_notifiers-268-rc4 2004-08-12 17:08:48.000000000 +0530
+++ linux-2.6.8-rc4-prasanna/arch/i386/kernel/traps.c 2004-08-12 17:09:47.000000000 +0530
@@ -48,6 +48,7 @@

#include <asm/smp.h>
#include <asm/arch_hooks.h>
+#include <asm/kdebug.h>

#include <linux/irq.h>
#include <linux/module.h>
@@ -92,6 +93,18 @@ asmlinkage void spurious_interrupt_bug(v
asmlinkage void machine_check(void);

static int kstack_depth_to_print = 24;
+struct notifier_block *i386die_chain;
+static spinlock_t die_notifier_lock = SPIN_LOCK_UNLOCKED;
+
+int register_die_notifier(struct notifier_block *nb)
+{
+ int err = 0;
+ unsigned long flags;
+ spin_lock_irqsave(&die_notifier_lock, flags);
+ err = notifier_chain_register(&i386die_chain, nb);
+ spin_unlock_irqrestore(&die_notifier_lock, flags);
+ return err;
+}

static int valid_stack_ptr(struct task_struct *task, void *p)
{
@@ -318,6 +331,7 @@ void die(const char * str, struct pt_reg
#endif
if (nl)
printk("\n");
+ notify_die(DIE_OOPS, (char *)str, regs, err, 255, SIGSEGV);
show_registers(regs);
bust_spinlocks(0);
spin_unlock_irq(&die_lock);
@@ -387,6 +401,9 @@ static inline void do_trap(int trapnr, i
#define DO_ERROR(trapnr, signr, str, name) \
asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
{ \
+ if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
+ == NOTIFY_OK) \
+ return; \
do_trap(trapnr, signr, str, 0, regs, error_code, NULL); \
}

@@ -398,12 +415,18 @@ asmlinkage void do_##name(struct pt_regs
info.si_errno = 0; \
info.si_code = sicode; \
info.si_addr = (void __user *)siaddr; \
+ if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
+ == NOTIFY_BAD) \
+ return; \
do_trap(trapnr, signr, str, 0, regs, error_code, &info); \
}

#define DO_VM86_ERROR(trapnr, signr, str, name) \
asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
{ \
+ if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
+ == NOTIFY_OK) \
+ return; \
do_trap(trapnr, signr, str, 1, regs, error_code, NULL); \
}

@@ -415,6 +438,9 @@ asmlinkage void do_##name(struct pt_regs
info.si_errno = 0; \
info.si_code = sicode; \
info.si_addr = (void __user *)siaddr; \
+ if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
+ == NOTIFY_OK) \
+ return; \
do_trap(trapnr, signr, str, 1, regs, error_code, &info); \
}

@@ -451,8 +477,12 @@ gp_in_vm86:
return;

gp_in_kernel:
- if (!fixup_exception(regs))
+ if (!fixup_exception(regs)) {
+ if (notify_die(DIE_GPF, "general protection fault", regs,
+ error_code, 13, SIGSEGV) == NOTIFY_OK);
+ return;
die("general protection fault", regs, error_code);
+ }
}

static void mem_parity_error(unsigned char reason, struct pt_regs * regs)
@@ -501,6 +531,9 @@ static void default_do_nmi(struct pt_reg
unsigned char reason = get_nmi_reason();

if (!(reason & 0xc0)) {
+ if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 0, SIGINT)
+ == NOTIFY_BAD)
+ return;
#ifdef CONFIG_X86_LOCAL_APIC
/*
* Ok, so this is none of the documented NMI sources,
@@ -514,6 +547,8 @@ static void default_do_nmi(struct pt_reg
unknown_nmi_error(reason, regs);
return;
}
+ if (notify_die(DIE_NMI, "nmi", regs, reason, 0, SIGINT) == NOTIFY_BAD)
+ return;
if (reason & 0x80)
mem_parity_error(reason, regs);
if (reason & 0x40)
@@ -587,6 +622,9 @@ asmlinkage void do_debug(struct pt_regs

__asm__ __volatile__("movl %%db6,%0" : "=r" (condition));

+ if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
+ SIGTRAP) == NOTIFY_OK)
+ return;
/* It's safe to allow irq's after DR6 has been saved */
if (regs->eflags & X86_EFLAGS_IF)
local_irq_enable();
diff -puN arch/i386/mm/fault.c~i386_exception_notifiers-268-rc4 arch/i386/mm/fault.c
--- linux-2.6.8-rc4/arch/i386/mm/fault.c~i386_exception_notifiers-268-rc4 2004-08-12 17:08:48.000000000 +0530
+++ linux-2.6.8-rc4-prasanna/arch/i386/mm/fault.c 2004-08-12 17:08:48.000000000 +0530
@@ -26,6 +26,7 @@
#include <asm/uaccess.h>
#include <asm/hardirq.h>
#include <asm/desc.h>
+#include <asm/kdebug.h>

extern void die(const char *,struct pt_regs *,long);

@@ -226,6 +227,9 @@ asmlinkage void do_page_fault(struct pt_
/* get the address */
__asm__("movl %%cr2,%0":"=r" (address));

+ if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
+ SIGSEGV) == NOTIFY_OK)
+ return;
/* It's safe to allow irq's after cr2 has been saved */
if (regs->eflags & (X86_EFLAGS_IF|VM_MASK))
local_irq_enable();
diff -puN /dev/null include/asm-i386/kdebug.h
--- /dev/null 2003-01-30 15:54:37.000000000 +0530
+++ linux-2.6.8-rc4-prasanna/include/asm-i386/kdebug.h 2004-08-12 17:08:48.000000000 +0530
@@ -0,0 +1,50 @@
+#ifndef _I386_KDEBUG_H
+#define _I386_KDEBUG_H 1
+
+/*
+ * Aug-05 2004 Ported by Prasanna S Panchamukhi <prasanna@in.ibm.com>
+ * from x86_64 architecture.
+ */
+#include <linux/notifier.h>
+
+struct pt_regs;
+
+struct die_args {
+ struct pt_regs *regs;
+ const char *str;
+ long err;
+ int trapnr;
+ int signr;
+};
+
+/* Note - you should never unregister because that can race with NMIs.
+ If you really want to do it first unregister - then synchronize_kernel - then free.
+ */
+int register_die_notifier(struct notifier_block *nb);
+extern struct notifier_block *i386die_chain;
+
+
+/* Grossly misnamed. */
+enum die_val {
+ DIE_OOPS = 1,
+ DIE_INT3,
+ DIE_DEBUG,
+ DIE_PANIC,
+ DIE_NMI,
+ DIE_DIE,
+ DIE_NMIWATCHDOG,
+ DIE_KERNELDEBUG,
+ DIE_TRAP,
+ DIE_GPF,
+ DIE_CALL,
+ DIE_NMI_IPI,
+ DIE_PAGE_FAULT,
+};
+
+static inline int notify_die(enum die_val val,char *str,struct pt_regs *regs,long err,int trap, int sig)
+{
+ struct die_args args = { .regs=regs, .str=str, .err=err, .trapnr=trap,.signr=sig };
+ return notifier_call_chain(&i386die_chain, val, &args);
+}
+
+#endif

_