From 94a46d316f2b54e3de8a4fa884cb16383db7fcd8 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 3 Apr 2020 22:37:31 +0200 Subject: [PATCH] x86/mce: Move nmi_enter/exit() into the entry point There is no reason to have nmi_enter/exit() in the actual MCE handlers. Move it to the entry point. This also covers the until now uncovered initial handler which only prints. Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra Acked-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20200505135314.243936614@linutronix.de --- arch/x86/kernel/cpu/mce/core.c | 26 +++++++++++++------------- arch/x86/kernel/cpu/mce/p5.c | 4 ---- arch/x86/kernel/cpu/mce/winchip.c | 4 ---- 3 files changed, 13 insertions(+), 21 deletions(-) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index e9265e2f28c9..f5993ed6e16b 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1100,8 +1100,10 @@ static void mce_clear_state(unsigned long *toclear) * kdump kernel establishing a new #MC handler where a broadcasted MCE * might not get handled properly. */ -static bool __mc_check_crashing_cpu(int cpu) +static noinstr bool mce_check_crashing_cpu(void) { + unsigned int cpu = smp_processor_id(); + if (cpu_is_offline(cpu) || (crashing_cpu != -1 && crashing_cpu != cpu)) { u64 mcgstatus; @@ -1235,7 +1237,6 @@ void noinstr do_machine_check(struct pt_regs *regs, long error_code) DECLARE_BITMAP(valid_banks, MAX_NR_BANKS); DECLARE_BITMAP(toclear, MAX_NR_BANKS); struct mca_config *cfg = &mca_cfg; - int cpu = smp_processor_id(); struct mce m, *final; char *msg = NULL; int worst = 0; @@ -1264,11 +1265,6 @@ void noinstr do_machine_check(struct pt_regs *regs, long error_code) */ int lmce = 1; - if (__mc_check_crashing_cpu(cpu)) - return; - - nmi_enter(); - this_cpu_inc(mce_exception_count); mce_gather_info(&m, regs); @@ -1356,7 +1352,7 @@ void noinstr do_machine_check(struct pt_regs *regs, long error_code) sync_core(); if (worst != MCE_AR_SEVERITY && !kill_it) - goto out_ist; + return; /* Fault was in user mode and we need to take some action */ if ((m.cs & 3) == 3) { @@ -1373,9 +1369,6 @@ void noinstr do_machine_check(struct pt_regs *regs, long error_code) if (!fixup_exception(regs, X86_TRAP_MC, error_code, 0)) mce_panic("Failed kernel mode recovery", &m, msg); } - -out_ist: - nmi_exit(); } EXPORT_SYMBOL_GPL(do_machine_check); @@ -1912,11 +1905,18 @@ static void unexpected_machine_check(struct pt_regs *regs, long error_code) void (*machine_check_vector)(struct pt_regs *, long error_code) = unexpected_machine_check; -dotraplinkage notrace void do_mce(struct pt_regs *regs, long error_code) +dotraplinkage noinstr void do_mce(struct pt_regs *regs, long error_code) { + if (machine_check_vector == do_machine_check && + mce_check_crashing_cpu()) + return; + + nmi_enter(); + machine_check_vector(regs, error_code); + + nmi_exit(); } -NOKPROBE_SYMBOL(do_mce); /* * Called for each booted CPU to set up machine checks. diff --git a/arch/x86/kernel/cpu/mce/p5.c b/arch/x86/kernel/cpu/mce/p5.c index 5ee94aa1b766..dc29f0f7b3ed 100644 --- a/arch/x86/kernel/cpu/mce/p5.c +++ b/arch/x86/kernel/cpu/mce/p5.c @@ -25,8 +25,6 @@ static void pentium_machine_check(struct pt_regs *regs, long error_code) { u32 loaddr, hi, lotype; - nmi_enter(); - rdmsr(MSR_IA32_P5_MC_ADDR, loaddr, hi); rdmsr(MSR_IA32_P5_MC_TYPE, lotype, hi); @@ -39,8 +37,6 @@ static void pentium_machine_check(struct pt_regs *regs, long error_code) } add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE); - - nmi_exit(); } /* Set up machine check reporting for processors with Intel style MCE: */ diff --git a/arch/x86/kernel/cpu/mce/winchip.c b/arch/x86/kernel/cpu/mce/winchip.c index b3938c195365..3f8f84ba0f51 100644 --- a/arch/x86/kernel/cpu/mce/winchip.c +++ b/arch/x86/kernel/cpu/mce/winchip.c @@ -19,12 +19,8 @@ /* Machine check handler for WinChip C6: */ static void winchip_machine_check(struct pt_regs *regs, long error_code) { - nmi_enter(); - pr_emerg("CPU0: Machine Check Exception.\n"); add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE); - - nmi_exit(); } /* Set up machine check reporting on the Winchip C6 series */