Currently, only kernel stack is checked for the overflow, which is not sufficient for systems that need a high reliability. To enhance it, it is required to check the IRQ and exception stacks, as well. This patch checks all the stack types and will cause messages of stacks in detail when free stack space drops below a certain limit except user stack. Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> --- arch/x86/Kconfig.debug | 7 +++++-- arch/x86/kernel/irq_64.c | 29 +++++++++++++++++++++++------ 2 files changed, 28 insertions(+), 8 deletions(-) diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index bf56e17..4caec12 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -63,8 +63,11 @@ config DEBUG_STACKOVERFLOW bool "Check for stack overflows" depends on DEBUG_KERNEL ---help--- - This option will cause messages to be printed if free stack space - drops below a certain limit. + Say Y here if you want to check the overflows of kernel, IRQ + and exception stacks. This option will cause messages of the + stacks in detail when free stack space drops below a certain + limit. + If in doubt, say "N". config X86_PTDUMP bool "Export kernel pagetable layout to userspace via debugfs" diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c index 69bca46..11ae893 100644 --- a/arch/x86/kernel/irq_64.c +++ b/arch/x86/kernel/irq_64.c @@ -36,18 +36,35 @@ EXPORT_PER_CPU_SYMBOL(irq_regs); static inline void stack_overflow_check(struct pt_regs *regs) { #ifdef CONFIG_DEBUG_STACKOVERFLOW + struct orig_ist *oist; + u64 irq_stack_top, irq_stack_bottom; + u64 estack_top, estack_bottom; u64 curbase = (u64)task_stack_page(current); if (user_mode_vm(regs)) return; - WARN_ONCE(regs->sp >= curbase && - regs->sp <= curbase + THREAD_SIZE && - regs->sp < curbase + sizeof(struct thread_info) + - sizeof(struct pt_regs) + 128, + if (regs->sp >= curbase && + regs->sp <= curbase + THREAD_SIZE && + regs->sp >= curbase + sizeof(struct thread_info) + + sizeof(struct pt_regs) + 128) + return; + + irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack); + irq_stack_bottom = (u64)__get_cpu_var(irq_stack_ptr); + if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom) + return; + + oist = &__get_cpu_var(orig_ist); + estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ; + estack_bottom = (u64)oist->ist[N_EXCEPTION_STACKS - 1]; + if (regs->sp >= estack_top && regs->sp <= estack_bottom) + return; - "do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n", - current->comm, curbase, regs->sp); + WARN_ONCE(1, "do_IRQ: %s near or already stack overflow (cur:%Lx,sp:%lx,irq stk top-bottom:%Lx-%Lx,exception stk top-bottom:%Lx-%Lx)\n", + current->comm, curbase, regs->sp, + irq_stack_top, irq_stack_bottom, + estack_top, estack_bottom); #endif } -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html