Commit 55ba18d6 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Thomas Gleixner
Browse files

x86/mce: Disable tracing and kprobes on do_machine_check() 



do_machine_check() can be raised in almost any context including the most
fragile ones. Prevent kprobes and tracing.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarAlexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200225220216.315548935@linutronix.de
parent 3d51507f

arch/x86/include/asm/traps.h

+0 −3
Original line number Diff line number Diff line
@@ -88,9 +88,6 @@ dotraplinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code, 
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);

arch/x86/kernel/cpu/mce/core.c

+10 −2
Original line number Diff line number Diff line
@@ -1213,8 +1213,14 @@ static void __mc_scan_banks(struct mce *m, struct mce *final, 
 * 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 @@ out_ist: 
	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(struct pt_regs *regs, long error_code) 
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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