diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-10-27 10:15:06 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-10-27 23:15:23 +0100 |
| commit | a195f3d4528a2f88d6f986f6b1101775ad4891cf (patch) | |
| tree | f61191d9faa00ce094e8a54b215e4de01262fec7 /arch/x86/kernel | |
| parent | 2a9baf5ad4884108b3c6d56a50e8105ccf8a4ee7 (diff) | |
x86/debug: Only clear/set ->virtual_dr6 for userspace #DB
The ->virtual_dr6 is the value used by ptrace_{get,set}_debugreg(6). A
kernel #DB clearing it could mean spurious malfunction of ptrace()
expectations.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kyle Huey <me@kylehuey.com>
Link: https://lore.kernel.org/r/20201027093608.028952500@infradead.org
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/traps.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index b5208aa7351f..32b2d39272e0 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -793,12 +793,6 @@ static __always_inline unsigned long debug_read_clear_dr6(void) set_debugreg(DR6_RESERVED, 6); dr6 ^= DR6_RESERVED; /* Flip to positive polarity */ - /* - * Clear the virtual DR6 value, ptrace routines will set bits here for - * things we want signals for. - */ - current->thread.virtual_dr6 = 0; - return dr6; } @@ -943,6 +937,12 @@ static __always_inline void exc_debug_user(struct pt_regs *regs, instrumentation_begin(); /* + * Clear the virtual DR6 value, ptrace() routines will set bits here + * for things it wants signals for. + */ + current->thread.virtual_dr6 = 0; + + /* * The SDM says "The processor clears the BTF flag when it * generates a debug exception." Clear TIF_BLOCKSTEP to keep * TIF_BLOCKSTEP in sync with the hardware BTF flag. |