From 041526ef7a7bc106036a8de75dc720766de93b6c Mon Sep 17 00:00:00 2001
From: Stepan Moskovchenko <stepanm@codeaurora.org>
Date: Thu, 13 Nov 2014 16:53:38 -0800
Subject: [PATCH] arm64: update die handler from ARM / x86
Commit 02df19b4227e5b799e4642e88b568f9474fa78d0 ("ARM:
7424/1: update die handler from x86") refactored the ARM
die() logic to avoid a deadlock if a kernel oops happens
while holding a spinlock that may also be used in an IRQ
handler. Refactor the ARM64 die() handler in a similar way,
to avoid similar deadlocks, which would have otherwise
prevented the kernel from printing the full panic output
and properly completing the panic() path.
Change-Id: I217a8d719f64b54467fa88a583d83f72193d7580
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
---
arch/arm64/kernel/traps.c | 66 +++++++++++++++++++++++++++++----------
1 file changed, 49 insertions(+), 17 deletions(-)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 73d9c4d85da2..605f8249325d 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -214,44 +214,76 @@ static int __die(const char *str, int err, struct thread_info *thread,
return ret;
}
-static DEFINE_RAW_SPINLOCK(die_lock);
+static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+static int die_owner = -1;
+static unsigned int die_nest_count;
-/*
- * This function is protected against re-entrancy.
- */
-void die(const char *str, struct pt_regs *regs, int err)
+static unsigned long oops_begin(void)
{
- struct thread_info *thread = current_thread_info();
- int ret;
- enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
+ int cpu;
+ unsigned long flags;
oops_enter();
- raw_spin_lock_irq(&die_lock);
+ /* racy, but better than risking deadlock. */
+ raw_local_irq_save(flags);
+ cpu = smp_processor_id();
+ if (!arch_spin_trylock(&die_lock)) {
+ if (cpu == die_owner)
+ /* nested oops. should stop eventually */;
+ else
+ arch_spin_lock(&die_lock);
+ }
+ die_nest_count++;
+ die_owner = cpu;
console_verbose();
bust_spinlocks(1);
- if (!user_mode(regs))
- bug_type = report_bug(regs->pc, regs);
- if (bug_type != BUG_TRAP_TYPE_NONE)
- str = "Oops - BUG";
- ret = __die(str, err, thread, regs);
+ return flags;
+}
- if (regs && kexec_should_crash(thread->task))
+static void oops_end(unsigned long flags, struct pt_regs *regs, int notify)
+{
+ if (regs && kexec_should_crash(current))
crash_kexec(regs);
bust_spinlocks(0);
+ die_owner = -1;
add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
- raw_spin_unlock_irq(&die_lock);
+ die_nest_count--;
+ if (!die_nest_count)
+ /* Nest count reaches zero, release the lock. */
+ arch_spin_unlock(&die_lock);
+ raw_local_irq_restore(flags);
oops_exit();
if (in_interrupt())
panic("Fatal exception in interrupt");
if (panic_on_oops)
panic("Fatal exception");
- if (ret != NOTIFY_STOP)
+ if (notify != NOTIFY_STOP)
do_exit(SIGSEGV);
}
+/*
+ * This function is protected against re-entrancy.
+ */
+void die(const char *str, struct pt_regs *regs, int err)
+{
+ struct thread_info *thread = current_thread_info();
+ enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
+ unsigned long flags = oops_begin();
+ int ret;
+
+ if (!user_mode(regs))
+ bug_type = report_bug(regs->pc, regs);
+ if (bug_type != BUG_TRAP_TYPE_NONE)
+ str = "Oops - BUG";
+
+ ret = __die(str, err, thread, regs);
+
+ oops_end(flags, regs, ret);
+}
+
void arm64_notify_die(const char *str, struct pt_regs *regs,
struct siginfo *info, int err)
{
--
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