From: Masami Hiramatsu (Google) <[email protected]> Add modify_wide_hw_breakpoint_local() arch-wide interface which allows hwbp users to update watch address on-line. This is available if the arch supports CONFIG_HAVE_REINSTALL_HW_BREAKPOINT. Note that this can not change the type because it does not release and reserve the hwbp slot based on type.
Signed-off-by: Masami Hiramatsu (Google) <[email protected]> --- arch/Kconfig | 10 +++++++++ arch/x86/Kconfig | 1 + arch/x86/include/asm/hw_breakpoint.h | 2 ++ arch/x86/kernel/hw_breakpoint.c | 11 ++++++++++ include/linux/hw_breakpoint.h | 6 ++++++ kernel/events/hw_breakpoint.c | 36 ++++++++++++++++++++++++++++++++++ 6 files changed, 66 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index d1b4ffd6e085..e4787fc814df 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -418,6 +418,16 @@ config HAVE_MIXED_BREAKPOINTS_REGS Select this option if your arch implements breakpoints under the latter fashion. +config HAVE_REINSTALL_HW_BREAKPOINT + bool + depends on HAVE_HW_BREAKPOINT + help + Depending on the arch implementation of hardware breakpoints, + some of them are able to update the breakpoint configuration + without release and reserve the hardware breakpoint register. + What configuration is able to update depends on hardware and + software implementation. + config HAVE_USER_RETURN_NOTIFIER bool diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 58d890fe2100..49d4ce2af94c 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -247,6 +247,7 @@ config X86 select HAVE_FUNCTION_TRACER select HAVE_GCC_PLUGINS select HAVE_HW_BREAKPOINT + select HAVE_REINSTALL_HW_BREAKPOINT select HAVE_IOREMAP_PROT select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 select HAVE_IRQ_TIME_ACCOUNTING diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw_breakpoint.h index bb7c70ad22fe..b3db25eb613f 100644 --- a/arch/x86/include/asm/hw_breakpoint.h +++ b/arch/x86/include/asm/hw_breakpoint.h @@ -64,6 +64,8 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp); void hw_breakpoint_pmu_read(struct perf_event *bp); void hw_breakpoint_pmu_unthrottle(struct perf_event *bp); +bool hw_breakpoint_arch_same_type(struct arch_hw_breakpoint *hw, + struct perf_event_attr *attr); extern void arch_fill_perf_breakpoint(struct perf_event *bp); diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index 89135229ed21..7dfc88ff6cd9 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -278,6 +278,17 @@ int arch_bp_generic_fields(int x86_len, int x86_type, return 0; } +bool hw_breakpoint_arch_same_type(struct arch_hw_breakpoint *hw, + struct perf_event_attr *attr) +{ + int glen, gtype; + + if (arch_bp_generic_fields(hw->len, hw->type, &glen, >ype) < 0) + return false; + + return gtype == attr->bp_type; +} + /* * Check for virtual address in kernel space. */ diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index db199d653dd1..ea373f2587f8 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -81,6 +81,9 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, perf_overflow_handler_t triggered, void *context); +extern int modify_wide_hw_breakpoint_local(struct perf_event *bp, + struct perf_event_attr *attr); + extern int register_perf_hw_breakpoint(struct perf_event *bp); extern void unregister_hw_breakpoint(struct perf_event *bp); extern void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events); @@ -124,6 +127,9 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, perf_overflow_handler_t triggered, void *context) { return NULL; } static inline int +modify_wide_hw_breakpoint_local(struct perf_event *bp, + struct perf_event_attr *attr) { return -ENOSYS; } +static inline int register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; } static inline void unregister_hw_breakpoint(struct perf_event *bp) { } static inline void diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index 8ec2cb688903..473a5b76941d 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -887,6 +887,42 @@ void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events) } EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint); +/** + * modify_wide_hw_breakpoint_local - update breakpoint config for local cpu + * @bp: the hwbp perf event for this cpu + * @attr: the new attribute for @bp + * + * This does not release and reserve the slot of HWBP, just reuse the current + * slot on local CPU. So the users must update the other CPUs by themselves. + * Also, since this does not release/reserve the slot, this can not change the + * type of the HWBP. + * Return err if attr is invalid or the cpu fails to update debug register + * for new @attr. + */ +#ifdef CONFIG_HAVE_REINSTALL_HW_BREAKPOINT +int modify_wide_hw_breakpoint_local(struct perf_event *bp, + struct perf_event_attr *attr) +{ + int ret; + + if (!hw_breakpoint_arch_same_type(counter_arch_bp(bp), attr)) + return -EINVAL; + + ret = hw_breakpoint_arch_parse(bp, attr, counter_arch_bp(bp)); + if (ret) + return ret; + + return arch_reinstall_hw_breakpoint(bp); +} +#else +int modify_wide_hw_breakpoint_local(struct perf_event *bp, + struct perf_event_attr *attr) +{ + return -EOPNOTSUPP; +} +#endif +EXPORT_SYMBOL_GPL(modify_wide_hw_breakpoint_local); + /** * hw_breakpoint_is_used - check if breakpoints are currently used *
