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authorJiri Olsa <jolsa@kernel.org>2018-08-27 11:12:25 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-08-30 14:49:23 -0300
commitbd14406b78e6daa1ea3c1673bda1ffc9efdeead0 (patch)
treec4957e82922f7772b726673a63b273733d3851ac /kernel
parent9b3579fc6c6ac45502de1fa9a1fdf873805c2157 (diff)
downloadlinux-stericsson-bd14406b78e6daa1ea3c1673bda1ffc9efdeead0.tar.gz
perf/hw_breakpoint: Modify breakpoint even if the new attr has disabled set
We need to change the breakpoint even if the attr with new fields has disabled set to true. Current code prevents following user code to change the breakpoint address: ptrace(PTRACE_POKEUSER, child, offsetof(struct user, u_debugreg[0]), addr_1) ptrace(PTRACE_POKEUSER, child, offsetof(struct user, u_debugreg[0]), addr_2) ptrace(PTRACE_POKEUSER, child, offsetof(struct user, u_debugreg[7]), dr7) The first PTRACE_POKEUSER creates the breakpoint with attr.disabled set to true: ptrace_set_breakpoint_addr(nr = 0) struct perf_event *bp = t->ptrace_bps[nr]; ptrace_register_breakpoint(..., disabled = true) ptrace_fill_bp_fields(..., disabled) register_user_hw_breakpoint So the second PTRACE_POKEUSER will be omitted: ptrace_set_breakpoint_addr(nr = 0) struct perf_event *bp = t->ptrace_bps[nr]; struct perf_event_attr attr = bp->attr; modify_user_hw_breakpoint(bp, &attr) if (!attr->disabled) modify_user_hw_breakpoint_check Reported-by: Milind Chabbi <chabbi.milind@gmail.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Frederic Weisbecker <frederic@kernel.org> Acked-by: Oleg Nesterov <oleg@redhat.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20180827091228.2878-3-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/hw_breakpoint.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index b3814fce5ecb..fb229d9c7f3c 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -509,6 +509,8 @@ modify_user_hw_breakpoint_check(struct perf_event *bp, struct perf_event_attr *a
*/
int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)
{
+ int err;
+
/*
* modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it
* will not be possible to raise IPIs that invoke __perf_event_disable.
@@ -520,11 +522,11 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att
else
perf_event_disable(bp);
- if (!attr->disabled) {
- int err = modify_user_hw_breakpoint_check(bp, attr, false);
+ err = modify_user_hw_breakpoint_check(bp, attr, false);
+ if (err)
+ return err;
- if (err)
- return err;
+ if (!attr->disabled) {
perf_event_enable(bp);
bp->attr.disabled = 0;
}