Commit-ID: ea6a9d530c1779b9bd30944b803820c462f01eac Gitweb: https://git.kernel.org/tip/ea6a9d530c1779b9bd30944b803820c462f01eac Author: Jiri Olsa <jo...@kernel.org> AuthorDate: Mon, 12 Mar 2018 14:45:43 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 13 Mar 2018 06:56:07 +0100
hw_breakpoint: Add modify_bp_slot() function Add the modify_bp_slot() function to keep slot numbers correct when changing the breakpoint type. Using existing __release_bp_slot()/__reserve_bp_slot() call sequence to update the slot counts. Signed-off-by: Jiri Olsa <jo...@kernel.org> Cc: Alexander Shishkin <alexander.shish...@linux.intel.com> Cc: Arnaldo Carvalho de Melo <a...@redhat.com> Cc: David Ahern <dsah...@gmail.com> Cc: Frederic Weisbecker <fweis...@gmail.com> Cc: Hari Bathini <hbath...@linux.vnet.ibm.com> Cc: Jin Yao <yao....@linux.intel.com> Cc: Jiri Olsa <jo...@redhat.com> Cc: Kan Liang <kan.li...@intel.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Michael Ellerman <m...@ellerman.id.au> Cc: Milind Chabbi <chabbi.mil...@gmail.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Oleg Nesterov <onest...@redhat.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Will Deacon <will.dea...@arm.com> Link: http://lkml.kernel.org/r/20180312134548.31532-4-jo...@kernel.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/events/hw_breakpoint.c | 46 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 39 insertions(+), 7 deletions(-) diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index 9b31fbcc3305..776948beb4ac 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -44,6 +44,7 @@ #include <linux/list.h> #include <linux/cpu.h> #include <linux/smp.h> +#include <linux/bug.h> #include <linux/hw_breakpoint.h> /* @@ -344,6 +345,38 @@ void release_bp_slot(struct perf_event *bp) mutex_unlock(&nr_bp_mutex); } +static int __modify_bp_slot(struct perf_event *bp, u64 old_type) +{ + int err; + + __release_bp_slot(bp, old_type); + + err = __reserve_bp_slot(bp, bp->attr.bp_type); + if (err) { + /* + * Reserve the old_type slot back in case + * there's no space for the new type. + * + * This must succeed, because we just released + * the old_type slot in the __release_bp_slot + * call above. If not, something is broken. + */ + WARN_ON(__reserve_bp_slot(bp, old_type)); + } + + return err; +} + +static int modify_bp_slot(struct perf_event *bp, u64 old_type) +{ + int ret; + + mutex_lock(&nr_bp_mutex); + ret = __modify_bp_slot(bp, old_type); + mutex_unlock(&nr_bp_mutex); + return ret; +} + /* * Allow the kernel debugger to reserve breakpoint slots without * taking a lock using the dbg_* variant of for the reserve and @@ -435,6 +468,7 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att u64 old_addr = bp->attr.bp_addr; u64 old_len = bp->attr.bp_len; int old_type = bp->attr.bp_type; + bool modify = attr->bp_type != old_type; int err = 0; /* @@ -452,12 +486,9 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att bp->attr.bp_type = attr->bp_type; bp->attr.bp_len = attr->bp_len; - if (attr->disabled) - goto end; - err = validate_hw_breakpoint(bp); - if (!err) - perf_event_enable(bp); + if (!err && modify) + err = modify_bp_slot(bp, old_type); if (err) { bp->attr.bp_addr = old_addr; @@ -469,9 +500,10 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att return err; } -end: - bp->attr.disabled = attr->disabled; + if (!attr->disabled) + perf_event_enable(bp); + bp->attr.disabled = attr->disabled; return 0; } EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
