Messages in this thread Patch in this message | | | Date | Tue, 25 Feb 2020 22:36:38 +0100 | From | Thomas Gleixner <> | Subject | [patch 02/10] x86/mce: Disable tracing and kprobes on do_machine_check() |
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From: Andy Lutomirski <luto@kernel.org>
do_machine_check() can be raised in almost any context including the most fragile ones. Prevent kprobes and tracing.
Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/include/asm/traps.h | 3 --- arch/x86/kernel/cpu/mce/core.c | 12 ++++++++++-- 2 files changed, 10 insertions(+), 5 deletions(-)
--- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -88,9 +88,6 @@ dotraplinkage void do_page_fault(struct dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *regs, long error_code); dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code); dotraplinkage void do_alignment_check(struct pt_regs *regs, long error_code); -#ifdef CONFIG_X86_MCE -dotraplinkage void do_machine_check(struct pt_regs *regs, long error_code); -#endif dotraplinkage void do_simd_coprocessor_error(struct pt_regs *regs, long error_code); #ifdef CONFIG_X86_32 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code); --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1213,8 +1213,14 @@ static void __mc_scan_banks(struct mce * * On Intel systems this is entered on all CPUs in parallel through * MCE broadcast. However some CPUs might be broken beyond repair, * so be always careful when synchronizing with others. + * + * Tracing and kprobes are disabled: if we interrupted a kernel context + * with IF=1, we need to minimize stack usage. There are also recursion + * issues: if the machine check was due to a failure of the memory + * backing the user stack, tracing that reads the user stack will cause + * potentially infinite recursion. */ -void do_machine_check(struct pt_regs *regs, long error_code) +void notrace do_machine_check(struct pt_regs *regs, long error_code) { DECLARE_BITMAP(valid_banks, MAX_NR_BANKS); DECLARE_BITMAP(toclear, MAX_NR_BANKS); @@ -1360,6 +1366,7 @@ void do_machine_check(struct pt_regs *re ist_exit(regs); } EXPORT_SYMBOL_GPL(do_machine_check); +NOKPROBE_SYMBOL(do_machine_check); #ifndef CONFIG_MEMORY_FAILURE int memory_failure(unsigned long pfn, int flags) @@ -1892,10 +1899,11 @@ static void unexpected_machine_check(str void (*machine_check_vector)(struct pt_regs *, long error_code) = unexpected_machine_check; -dotraplinkage void do_mce(struct pt_regs *regs, long error_code) +dotraplinkage notrace void do_mce(struct pt_regs *regs, long error_code) { machine_check_vector(regs, error_code); } +NOKPROBE_SYMBOL(do_mce); /* * Called for each booted CPU to set up machine checks.
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