diff options
| author | Andy Lutomirski <luto@amacapital.net> | 2014-11-19 17:41:09 -0800 |
|---|---|---|
| committer | Andy Lutomirski <luto@amacapital.net> | 2015-01-02 10:22:46 -0800 |
| commit | 959274753857efe9c5f1ba35fe727f51e9aa128d (patch) | |
| tree | 57532e8c2738c21a90d47ac0e23dcc3f81ffd29b /arch/x86/kernel/cpu/mcheck/winchip.c | |
| parent | 48e08d0fb265b007ebbb29a72297ff7e40938969 (diff) | |
x86, traps: Track entry into and exit from IST context
We currently pretend that IST context is like standard exception
context, but this is incorrect. IST entries from userspace are like
standard exceptions except that they use per-cpu stacks, so they are
atomic. IST entries from kernel space are like NMIs from RCU's
perspective -- they are not quiescent states even if they
interrupted the kernel during a quiescent state.
Add and use ist_enter and ist_exit to track IST context. Even
though x86_32 has no IST stacks, we track these interrupts the same
way.
This fixes two issues:
- Scheduling from an IST interrupt handler will now warn. It would
previously appear to work as long as we got lucky and nothing
overwrote the stack frame. (I don't know of any bugs in this
that would trigger the warning, but it's good to be on the safe
side.)
- RCU handling in IST context was dangerous. As far as I know,
only machine checks were likely to trigger this, but it's good to
be on the safe side.
Note that the machine check handlers appears to have been missing
any context tracking at all before this patch.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Diffstat (limited to 'arch/x86/kernel/cpu/mcheck/winchip.c')
| -rw-r--r-- | arch/x86/kernel/cpu/mcheck/winchip.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/mcheck/winchip.c b/arch/x86/kernel/cpu/mcheck/winchip.c index 7dc5564d0cdf..bd5d46a32210 100644 --- a/arch/x86/kernel/cpu/mcheck/winchip.c +++ b/arch/x86/kernel/cpu/mcheck/winchip.c @@ -7,14 +7,19 @@ #include <linux/types.h> #include <asm/processor.h> +#include <asm/traps.h> #include <asm/mce.h> #include <asm/msr.h> /* Machine check handler for WinChip C6: */ static void winchip_machine_check(struct pt_regs *regs, long error_code) { + enum ctx_state prev_state = ist_enter(regs); + printk(KERN_EMERG "CPU0: Machine Check Exception.\n"); add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE); + + ist_exit(regs, prev_state); } /* Set up machine check reporting on the Winchip C6 series */ |