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Commit 02be46fb authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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ptrace/x86: revert "hw_breakpoints: Fix racy access to ptrace breakpoints" 



This reverts commit 87dc669b ("hw_breakpoints: Fix racy access to
ptrace breakpoints").

The patch was fine but we can no longer race with SIGKILL after commit
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: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarFrederic 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6e5b93ee

arch/x86/kernel/ptrace.c

+5 −23
Original line number Diff line number Diff line
@@ -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;

}