From 02be46fba4b154b4a201a729b2d2b4ff6affd031 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 8 Jul 2013 16:00:47 -0700 Subject: [PATCH] ptrace/x86: revert "hw_breakpoints: Fix racy access to ptrace breakpoints" This reverts commit 87dc669ba257 ("hw_breakpoints: Fix racy access to ptrace breakpoints"). The patch was fine but we can no longer race with SIGKILL after commit 9899d11f6544 ("ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL"), the __TASK_TRACED tracee can't be woken up and ->ptrace_bps[] can't go away. The patch only removes ptrace_get_breakpoints/ptrace_put_breakpoints and does a couple of "while at it" cleanups, it doesn't remove other changes from the reverted commit. Signed-off-by: Oleg Nesterov Acked-by: Ingo Molnar Acked-by: Frederic Weisbecker Cc: Benjamin Herrenschmidt Cc: Jan Kratochvil Cc: Michael Neuling Cc: Paul Mackerras Cc: Paul Mundt Cc: Will Deacon Cc: Prasad Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/kernel/ptrace.c | 28 +++++----------------------- 1 file changed, 5 insertions(+), 23 deletions(-) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 29a8120e6fe8..7a98b21945aa 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -641,9 +641,6 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data) unsigned len, type; struct perf_event *bp; - if (ptrace_get_breakpoints(tsk) < 0) - return -ESRCH; - data &= ~DR_CONTROL_RESERVED; old_dr7 = ptrace_get_dr7(thread->ptrace_bps); restore: @@ -692,9 +689,7 @@ restore: goto restore; } - ptrace_put_breakpoints(tsk); - - return ((orig_ret < 0) ? orig_ret : rc); + return orig_ret < 0 ? orig_ret : rc; } /* @@ -706,18 +701,10 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n) unsigned long val = 0; if (n < HBP_NUM) { - struct perf_event *bp; + struct perf_event *bp = thread->ptrace_bps[n]; - if (ptrace_get_breakpoints(tsk) < 0) - return -ESRCH; - - bp = thread->ptrace_bps[n]; - if (!bp) - val = 0; - else + if (bp) val = bp->hw.info.address; - - ptrace_put_breakpoints(tsk); } else if (n == 6) { val = thread->debugreg6; } else if (n == 7) { @@ -734,9 +721,6 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr, struct perf_event_attr attr; int err = 0; - if (ptrace_get_breakpoints(tsk) < 0) - return -ESRCH; - if (!t->ptrace_bps[nr]) { ptrace_breakpoint_init(&attr); /* @@ -762,7 +746,7 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr, */ if (IS_ERR(bp)) { err = PTR_ERR(bp); - goto put; + goto out; } t->ptrace_bps[nr] = bp; @@ -773,9 +757,7 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr, attr.bp_addr = addr; err = modify_user_hw_breakpoint(bp, &attr); } - -put: - ptrace_put_breakpoints(tsk); +out: return err; } -- 2.20.1