From 2c31b7958fd21df9fa04e5c36cda0f063ac70b27 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 26 Nov 2009 06:04:38 +0100 Subject: [PATCH] x86/hw-breakpoints: Don't lose GE flag while disabling a breakpoint When we schedule out a breakpoint from the cpu, we also incidentally remove the "Global exact breakpoint" flag from the breakpoint control register. It makes us losing the fine grained precision about the origin of the instructions that may trigger breakpoint exceptions for the other breakpoints running in this cpu. Reported-by: Prasad Signed-off-by: Frederic Weisbecker LKML-Reference: <1259211878-6013-1-git-send-regression-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/hw_breakpoint.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index 92ea5aad0b5c..d42f65ac4927 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -59,21 +59,27 @@ static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]); static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]); -/* - * Encode the length, type, Exact, and Enable bits for a particular breakpoint - * as stored in debug register 7. - */ -unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type) +static inline unsigned long +__encode_dr7(int drnum, unsigned int len, unsigned int type) { unsigned long bp_info; bp_info = (len | type) & 0xf; bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE); - bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)) | - DR_GLOBAL_SLOWDOWN; + bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)); + return bp_info; } +/* + * Encode the length, type, Exact, and Enable bits for a particular breakpoint + * as stored in debug register 7. + */ +unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type) +{ + return __encode_dr7(drnum, len, type) | DR_GLOBAL_SLOWDOWN; +} + /* * Decode the length and type bits for a particular breakpoint as * stored in debug register 7. Return the "enabled" status. @@ -154,7 +160,7 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp) return; dr7 = &__get_cpu_var(cpu_dr7); - *dr7 &= ~encode_dr7(i, info->len, info->type); + *dr7 &= ~__encode_dr7(i, info->len, info->type); set_debugreg(*dr7, 7); } -- 2.20.1