LoongArch: Do not kill the task in die() if notify_die() returns NOTIFY_STOP

If notify_die() returns NOTIFY_STOP, honor the return value from the
handler chain invocation in die() and return without killing the task
as, through a debugger, the fault may have been fixed. It makes sense
even if ignoring the event will make the system unstable: by allowing
access through a debugger it has been compromised already anyway. It
makes our port consistent with x86, arm64, riscv and csky.

Commit 20c0d2d44029 ("[PATCH] i386: pass proper trap numbers to die
chain handlers") may be the earliest of similar changes.

Link: https://lore.kernel.org/r/43DDF02E.76F0.0078.0@novell.com/
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/include/asm/ptrace.h b/arch/loongarch/include/asm/ptrace.h
index 35f0958..164bc90 100644 (file)
--- a/arch/loongarch/include/asm/ptrace.h
+++ b/arch/loongarch/include/asm/ptrace.h
@@ -162,7 +162,7 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long val
 #define instruction_pointer(regs) ((regs)->csr_era)
 #define profile_pc(regs) instruction_pointer(regs)
 
-extern void die(const char *, struct pt_regs *) __noreturn;
+extern void die(const char *, struct pt_regs *);
 
 static inline void die_if_kernel(const char *str, struct pt_regs *regs)
 {

diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index 8fb5e7a..dfb34cc 100644 (file)
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -383,16 +383,15 @@ void show_registers(struct pt_regs *regs)
 
 static DEFINE_RAW_SPINLOCK(die_lock);
 
-void __noreturn die(const char *str, struct pt_regs *regs)
+void die(const char *str, struct pt_regs *regs)
 {
+       int ret;
        static int die_counter;
-       int sig = SIGSEGV;
 
        oops_enter();
 
-       if (notify_die(DIE_OOPS, str, regs, 0, current->thread.trap_nr,
-                      SIGSEGV) == NOTIFY_STOP)
-               sig = 0;
+       ret = notify_die(DIE_OOPS, str, regs, 0,
+                        current->thread.trap_nr, SIGSEGV);
 
        console_verbose();
        raw_spin_lock_irq(&die_lock);
@@ -414,7 +413,8 @@ void __noreturn die(const char *str, struct pt_regs *regs)
        if (panic_on_oops)
                panic("Fatal exception");
 
-       make_task_dead(sig);
+       if (ret != NOTIFY_STOP)
+               make_task_dead(SIGSEGV);
 }
 
 static inline void setup_vint_size(unsigned int size)