diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-09-02 15:26:02 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-09-04 15:12:58 +0200 |
| commit | d53d9bc0cf783e93b374de3895145c7375e570ba (patch) | |
| tree | fb95a9c74cba7e6a7d93f58f80f542e941f99997 /arch/x86/kernel/hw_breakpoint.c | |
| parent | f4956cf83ed12271bdbd5b547f3378add72bbffb (diff) | |
x86/debug: Change thread.debugreg6 to thread.virtual_dr6
Current usage of thread.debugreg6 is convoluted at best. It starts life as
a copy of the hardware DR6 value, but then various bits are cleared and
set.
Replace this with a new variable thread.virtual_dr6 that is initialized to
0 when DR6 is read and only gains bits, at the same time the actual (on
stack) dr6 value which is read from the hardware only gets bits cleared.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20200902133201.415372940@infradead.org
Diffstat (limited to 'arch/x86/kernel/hw_breakpoint.c')
| -rw-r--r-- | arch/x86/kernel/hw_breakpoint.c | 12 |
1 files changed, 3 insertions, 9 deletions
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index d17a1daeff71..03aa33b58165 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -454,7 +454,7 @@ void flush_ptrace_hw_breakpoint(struct task_struct *tsk) t->ptrace_bps[i] = NULL; } - t->debugreg6 = 0; + t->virtual_dr6 = 0; t->ptrace_dr7 = 0; } @@ -489,8 +489,8 @@ static int hw_breakpoint_handler(struct die_args *args) { int i, rc = NOTIFY_STOP; struct perf_event *bp; - unsigned long dr6; unsigned long *dr6_p; + unsigned long dr6; /* The DR6 value is pointed by args->err */ dr6_p = (unsigned long *)ERR_PTR(args->err); @@ -504,12 +504,6 @@ static int hw_breakpoint_handler(struct die_args *args) if ((dr6 & DR_TRAP_BITS) == 0) return NOTIFY_DONE; - /* - * Reset the DRn bits in the virtualized register value. - * The ptrace trigger routine will add in whatever is needed. - */ - current->thread.debugreg6 &= ~DR_TRAP_BITS; - /* Handle all the breakpoints that were triggered */ for (i = 0; i < HBP_NUM; ++i) { if (likely(!(dr6 & (DR_TRAP0 << i)))) @@ -554,7 +548,7 @@ static int hw_breakpoint_handler(struct die_args *args) * breakpoints (to generate signals) and b) when the system has * taken exception due to multiple causes */ - if ((current->thread.debugreg6 & DR_TRAP_BITS) || + if ((current->thread.virtual_dr6 & DR_TRAP_BITS) || (dr6 & (~DR_TRAP_BITS))) rc = NOTIFY_DONE; |