24f1e32c "hw-breakpoints: Rewrite the hw-breakpoints layer on top
of perf events" introduced the minor regression. Before this commit
PTRACE_POKEUSER DR7, enableDR0
PTRACE_POKEUSER DR0, address
was perfectly valid, now PTRACE_POKEUSER(DR7) fails if DR0 was not
previously initialized by PTRACE_POKEUSER(DR0).
Change ptrace_write_dr7() to do ptrace_register_breakpoint(addr => 0)
if !bp && !disabled. This fixes watchpoint-zeroaddr from ptrace-tests,
see https://bugzilla.redhat.com/show_bug.cgi?id=660204.
Reported-by: Jan Kratochvil <jan.kratoch...@redhat.com>
Signed-off-by: Oleg Nesterov <o...@redhat.com>
Acked-by: Frederic Weisbecker <fweis...@gmail.com>
---
arch/x86/kernel/ptrace.c | 17 ++++++++++-------
1 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 0526368..5c387b3 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -670,13 +670,16 @@ restore:
if (!bp) {
if (disabled)
continue;
- /*
- * We should have at least an inactive breakpoint at
- * this slot. It means the user is writing dr7 without
- * having written the address register first.
- */
- rc = -EINVAL;
- break;
+
+ bp = ptrace_register_breakpoint(tsk,
+ len, type, 0, disabled);
+ if (IS_ERR(bp)) {
+ rc = PTR_ERR(bp);
+ break;
+ }
+
+ thread->ptrace_bps[i] = bp;
+ continue;
}
rc = ptrace_modify_breakpoint(bp, len, type, disabled);
--
1.5.5.1
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