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

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This reverts commit 07fa7a0a8a ("hw_breakpoints: Fix racy access to
ptrace breakpoints") and removes ptrace_get/put_breakpoints() added by
other commits.

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.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Michael Neuling <mikey@neuling.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
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 16:00:49 -07:00 committed by Linus Torvalds
parent 02be46fba4
commit 6961ed96f1
1 changed files with 4 additions and 26 deletions
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30
arch/powerpc/kernel/ptrace.c
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@ -975,16 +975,12 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
hw_brk.type = (data & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL;
hw_brk.len = 8;
#ifdef CONFIG_HAVE_HW_BREAKPOINT
if (ptrace_get_breakpoints(task) < 0)
return -ESRCH;
bp = thread->ptrace_bps[0];
if ((!data) || !(hw_brk.type & HW_BRK_TYPE_RDWR)) {
if (bp) {
unregister_hw_breakpoint(bp);
thread->ptrace_bps[0] = NULL;
}
ptrace_put_breakpoints(task);
return 0;
}
if (bp) {
@ -997,11 +993,9 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
ret = modify_user_hw_breakpoint(bp, &attr);
if (ret) {
ptrace_put_breakpoints(task);
return ret;
}
thread->ptrace_bps[0] = bp;
ptrace_put_breakpoints(task);
thread->hw_brk = hw_brk;
return 0;
}
@ -1016,12 +1010,9 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
ptrace_triggered, NULL, task);
if (IS_ERR(bp)) {
thread->ptrace_bps[0] = NULL;
ptrace_put_breakpoints(task);
return PTR_ERR(bp);
}
ptrace_put_breakpoints(task);
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
task->thread.hw_brk = hw_brk;
#else /* CONFIG_PPC_ADV_DEBUG_REGS */
@ -1440,26 +1431,19 @@ static long ppc_set_hwdebug(struct task_struct *child,
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE)
brk.type |= HW_BRK_TYPE_WRITE;
#ifdef CONFIG_HAVE_HW_BREAKPOINT
if (ptrace_get_breakpoints(child) < 0)
return -ESRCH;
/*
* Check if the request is for 'range' breakpoints. We can
* support it if range < 8 bytes.
*/
if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE) {
if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE)
len = bp_info->addr2 - bp_info->addr;
} else if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_EXACT)
else if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_EXACT)
len = 1;
else {
ptrace_put_breakpoints(child);
else
return -EINVAL;
}
bp = thread->ptrace_bps[0];
if (bp) {
ptrace_put_breakpoints(child);
if (bp)
return -ENOSPC;
}
/* Create a new breakpoint request if one doesn't exist already */
hw_breakpoint_init(&attr);
@ -1471,11 +1455,9 @@ static long ppc_set_hwdebug(struct task_struct *child,
ptrace_triggered, NULL, child);
if (IS_ERR(bp)) {
thread->ptrace_bps[0] = NULL;
ptrace_put_breakpoints(child);
return PTR_ERR(bp);
}
ptrace_put_breakpoints(child);
return 1;
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
@ -1519,16 +1501,12 @@ static long ppc_del_hwdebug(struct task_struct *child, long data)
return -EINVAL;
#ifdef CONFIG_HAVE_HW_BREAKPOINT
if (ptrace_get_breakpoints(child) < 0)
return -ESRCH;
bp = thread->ptrace_bps[0];
if (bp) {
unregister_hw_breakpoint(bp);
thread->ptrace_bps[0] = NULL;
} else
ret = -ENOENT;
ptrace_put_breakpoints(child);
return ret;
#else /* CONFIG_HAVE_HW_BREAKPOINT */
if (child->thread.hw_brk.address == 0)