From: Frederic Weisbecker Date: Thu, 26 Nov 2009 05:04:38 +0000 (+0100) Subject: x86/hw-breakpoints: Don't lose GE flag while disabling a breakpoint X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=2c31b7958fd21df9fa04e5c36cda0f063ac70b27;p=openwrt%2Fstaging%2Fblogic.git 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 --- 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); }