From 6961ed96f14463d7c6e38d8c2093f5d53bd70574 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 8 Jul 2013 16:00:49 -0700 Subject: [PATCH] ptrace/powerpc: revert "hw_breakpoints: Fix racy access to ptrace breakpoints" This reverts commit 07fa7a0a8a58 ("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 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. Signed-off-by: Oleg Nesterov Acked-by: Michael Neuling Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jan Kratochvil Cc: Paul Mundt Cc: Will Deacon Cc: Prasad Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/powerpc/kernel/ptrace.c | 30 ++++-------------------------- 1 file changed, 4 insertions(+), 26 deletions(-) diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index 64f7bd5b1b0f..9a0d24c390a3 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -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) -- 2.20.1