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hw_breakpoint: Add modify_bp_slot() function

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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 <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Milind Chabbi <chabbi.milind@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <onestero@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20180312134548.31532-4-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Jiri Olsa 2018-03-12 14:45:43 +01:00 committed by Ingo Molnar
parent 1ad9ff7dea
commit ea6a9d530c
1 changed files with 39 additions and 7 deletions
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46
kernel/events/hw_breakpoint.c
View file

@ -44,6 +44,7 @@
#include <linux/list.h> #include <linux/list.h>
#include <linux/cpu.h> #include <linux/cpu.h>
#include <linux/smp.h> #include <linux/smp.h>
#include <linux/bug.h>
#include <linux/hw_breakpoint.h> #include <linux/hw_breakpoint.h>
/* /*
@ -344,6 +345,38 @@ void release_bp_slot(struct perf_event *bp)
mutex_unlock(&nr_bp_mutex); 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 * Allow the kernel debugger to reserve breakpoint slots without
* taking a lock using the dbg_* variant of for the reserve and * 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_addr = bp->attr.bp_addr;
u64 old_len = bp->attr.bp_len; u64 old_len = bp->attr.bp_len;
int old_type = bp->attr.bp_type; int old_type = bp->attr.bp_type;
bool modify = attr->bp_type != old_type;
int err = 0; 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_type = attr->bp_type;
bp->attr.bp_len = attr->bp_len; bp->attr.bp_len = attr->bp_len;
if (attr->disabled)
goto end;
err = validate_hw_breakpoint(bp); err = validate_hw_breakpoint(bp);
if (!err) if (!err && modify)
perf_event_enable(bp); err = modify_bp_slot(bp, old_type);
if (err) { if (err) {
bp->attr.bp_addr = old_addr; 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; return err;
} }
end: if (!attr->disabled)
bp->attr.disabled = attr->disabled; perf_event_enable(bp);
bp->attr.disabled = attr->disabled;
return 0; return 0;
} }
EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);