From 02be46fba4b154b4a201a729b2d2b4ff6affd031 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
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 <oleg@redhat.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
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 29a8120e6fe88..7a98b21945aaf 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;
}
--
2.30.2