diff options
| author | Andy Lutomirski <luto@kernel.org> | 2017-09-07 22:06:57 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-09-13 09:50:52 +0200 |
| commit | a376e7f99be7c1e15b2d986e49b2bec834904381 (patch) | |
| tree | 29c44ce51dd613763c98118d010910252f15ff5c | |
| parent | 6d8ef53e8b2fed8b0f91df0c6da7cc92747d934a (diff) | |
x86/mm: Get rid of VM_BUG_ON in switch_tlb_irqs_off()
If we hit the VM_BUG_ON(), we're detecting a genuinely bad situation,
but we're very unlikely to get a useful call trace.
Make it a warning instead.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3b4e06bbb382ca54a93218407c93925ff5871546.1504847163.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/mm/tlb.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 37689a7cc03b..1ab3821f9e26 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -121,8 +121,28 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, * hypothetical buggy code that directly switches to swapper_pg_dir * without going through leave_mm() / switch_mm_irqs_off() or that * does something like write_cr3(read_cr3_pa()). + * + * Only do this check if CONFIG_DEBUG_VM=y because __read_cr3() + * isn't free. */ - VM_BUG_ON(__read_cr3() != (__sme_pa(real_prev->pgd) | prev_asid)); +#ifdef CONFIG_DEBUG_VM + if (WARN_ON_ONCE(__read_cr3() != + (__sme_pa(real_prev->pgd) | prev_asid))) { + /* + * If we were to BUG here, we'd be very likely to kill + * the system so hard that we don't see the call trace. + * Try to recover instead by ignoring the error and doing + * a global flush to minimize the chance of corruption. + * + * (This is far from being a fully correct recovery. + * Architecturally, the CPU could prefetch something + * back into an incorrect ASID slot and leave it there + * to cause trouble down the road. It's better than + * nothing, though.) + */ + __flush_tlb_all(); + } +#endif if (real_prev == next) { VM_BUG_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) != |