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ptrace/x86: revert "hw_breakpoints: Fix racy access to ptrace breakpoints"

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This reverts commit 87dc669ba2 ("hw_breakpoints: Fix racy access to
ptrace breakpoints").

The patch was fine but we can no longer race with SIGKILL after commit
9899d11f65 ("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>
This commit is contained in:
Oleg Nesterov 2013-07-08 16:00:47 -07:00 committed by Linus Torvalds
parent 6e5b93ee55
commit 02be46fba4
1 changed files with 5 additions and 23 deletions
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28
arch/x86/kernel/ptrace.c
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@ -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 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data)
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;
}