From 1cedae72904b85462082dbcfd5190309ba37f8bd Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 2 Dec 2009 07:32:16 +0100 Subject: [PATCH] hw-breakpoints: Keep track of user disabled breakpoints When we disable a breakpoint through dr7, we unregister it right away, making us lose track of its corresponding address register value. It means that the following sequence would be unsupported: - set address in dr0 - enable it through dr7 - disable it through dr7 - enable it through dr7 because we lost the address register value when we disabled the breakpoint. Don't unregister the disabled breakpoints but rather disable them. Reported-by: "K.Prasad" Signed-off-by: Frederic Weisbecker LKML-Reference: <1259735536-9236-1-git-send-regression-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/ptrace.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 2941b32ea666..04d182a7cfdb 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -595,7 +595,7 @@ static unsigned long ptrace_get_dr7(struct perf_event *bp[]) static struct perf_event * ptrace_modify_breakpoint(struct perf_event *bp, int len, int type, - struct task_struct *tsk) + struct task_struct *tsk, int disabled) { int err; int gen_len, gen_type; @@ -616,7 +616,7 @@ ptrace_modify_breakpoint(struct perf_event *bp, int len, int type, attr = bp->attr; attr.bp_len = gen_len; attr.bp_type = gen_type; - attr.disabled = 0; + attr.disabled = disabled; return modify_user_hw_breakpoint(bp, &attr, bp->callback, tsk); } @@ -655,13 +655,21 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data) */ if (!second_pass) continue; + thread->ptrace_bps[i] = NULL; - unregister_hw_breakpoint(bp); + bp = ptrace_modify_breakpoint(bp, len, type, + tsk, 1); + if (IS_ERR(bp)) { + rc = PTR_ERR(bp); + thread->ptrace_bps[i] = NULL; + break; + } + thread->ptrace_bps[i] = bp; } continue; } - bp = ptrace_modify_breakpoint(bp, len, type, tsk); + bp = ptrace_modify_breakpoint(bp, len, type, tsk, 0); /* Incorrect bp, or we have a bug in bp API */ if (IS_ERR(bp)) { -- GitLab