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Message-ID: <20130414160526.GA7635@redhat.com>
Date: Sun, 14 Apr 2013 18:05:26 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Jan Kratochvil <jan.kratochvil@...hat.com>,
Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
Paul Mundt <lethal@...ux-sh.org>,
Prasad <prasad@...ux.vnet.ibm.com>,
Russell King <linux@....linux.org.uk>,
Will Deacon <will.deacon@....com>, linux-kernel@...r.kernel.org
Subject: [PATCH 1/5] ptrace/x86: Revert "hw_breakpoints: Fix racy access to
ptrace breakpoints"
This reverts commit 87dc669ba25777b67796d7262c569429e58b1ed4.
The patch was fine but we can no longer race with SIGKILL after
9899d11f "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@...hat.com>
---
arch/x86/kernel/ptrace.c | 28 +++++-----------------------
1 files changed, 5 insertions(+), 23 deletions(-)
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 29a8120..7a98b21 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;
}
--
1.5.5.1
--
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