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x86/mce: Send #MC singal from task work

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Convert #MC over to using task_work_add(); it will run the same code
slightly later, on the return to user path of the same exception.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134100.957390899@linutronix.de
This commit is contained in:
Peter Zijlstra 2020-02-19 10:22:06 +01:00 committed by Thomas Gleixner
parent b052df3da8
commit 5567d11c21
2 changed files with 37 additions and 25 deletions
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56
arch/x86/kernel/cpu/mce/core.c
View File

@ -42,6 +42,7 @@
#include <linux/export.h>
#include <linux/jump_label.h>
#include <linux/set_memory.h>
#include <linux/task_work.h>
#include <asm/intel-family.h>
#include <asm/processor.h>
@ -1086,23 +1087,6 @@ static void mce_clear_state(unsigned long *toclear)
}
}
static int do_memory_failure(struct mce *m)
{
int flags = MF_ACTION_REQUIRED;
int ret;
pr_err("Uncorrected hardware memory error in user-access at %llx", m->addr);
if (!(m->mcgstatus & MCG_STATUS_RIPV))
flags |= MF_MUST_KILL;
ret = memory_failure(m->addr >> PAGE_SHIFT, flags);
if (ret)
pr_err("Memory error not recovered");
else
set_mce_nospec(m->addr >> PAGE_SHIFT);
return ret;
}
/*
* Cases where we avoid rendezvous handler timeout:
* 1) If this CPU is offline.
@ -1204,6 +1188,29 @@ static void __mc_scan_banks(struct mce *m, struct mce *final,
*m = *final;
}
static void kill_me_now(struct callback_head *ch)
{
force_sig(SIGBUS);
}
static void kill_me_maybe(struct callback_head *cb)
{
struct task_struct *p = container_of(cb, struct task_struct, mce_kill_me);
int flags = MF_ACTION_REQUIRED;
pr_err("Uncorrected hardware memory error in user-access at %llx", p->mce_addr);
if (!(p->mce_status & MCG_STATUS_RIPV))
flags |= MF_MUST_KILL;
if (!memory_failure(p->mce_addr >> PAGE_SHIFT, flags)) {
set_mce_nospec(p->mce_addr >> PAGE_SHIFT);
return;
}
pr_err("Memory error not recovered");
kill_me_now(cb);
}
/*
* The actual machine check handler. This only handles real
* exceptions when something got corrupted coming in through int 18.
@ -1222,7 +1229,7 @@ static void __mc_scan_banks(struct mce *m, struct mce *final,
* backing the user stack, tracing that reads the user stack will cause
* potentially infinite recursion.
*/
void notrace do_machine_check(struct pt_regs *regs, long error_code)
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);
@ -1354,13 +1361,13 @@ void notrace do_machine_check(struct pt_regs *regs, long error_code)
if ((m.cs & 3) == 3) {
/* If this triggers there is no way to recover. Die hard. */
BUG_ON(!on_thread_stack() || !user_mode(regs));
local_irq_enable();
preempt_enable();
if (kill_it || do_memory_failure(&m))
force_sig(SIGBUS);
preempt_disable();
local_irq_disable();
current->mce_addr = m.addr;
current->mce_status = m.mcgstatus;
current->mce_kill_me.func = kill_me_maybe;
if (kill_it)
current->mce_kill_me.func = kill_me_now;
task_work_add(current, &current->mce_kill_me, true);
} else {
if (!fixup_exception(regs, X86_TRAP_MC, error_code, 0))
mce_panic("Failed kernel mode recovery", &m, msg);
@ -1370,7 +1377,6 @@ void notrace do_machine_check(struct pt_regs *regs, long error_code)
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)

6
include/linux/sched.h
View File

@ -1297,6 +1297,12 @@ struct task_struct {
unsigned long prev_lowest_stack;
#endif
#ifdef CONFIG_X86_MCE
u64 mce_addr;
u64 mce_status;
struct callback_head mce_kill_me;
#endif
/*
* New fields for task_struct should be added above here, so that
* they are included in the randomized portion of task_struct.