diff options
| author | Will Deacon <will.deacon@arm.com> | 2011-02-14 14:31:09 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2011-02-23 17:24:22 +0000 |
| commit | 425fc47adb5bb69f76285be77a09a3341a30799e (patch) | |
| tree | aa1fab1e90520f80573445c77b55db8446e3570c /arch/arm/kernel/ptrace.h | |
| parent | 5637a126482026b37d426d76e1b18f748f309aaa (diff) | |
ARM: 6668/1: ptrace: remove single-step emulation code
PTRACE_SINGLESTEP is a ptrace request designed to offer single-stepping
support to userspace when the underlying architecture has hardware
support for this operation.
On ARM, we set arch_has_single_step() to 1 and attempt to emulate hardware
single-stepping by disassembling the current instruction to determine the
next pc and placing a software breakpoint on that location.
Unfortunately this has the following problems:
1.) Only a subset of ARMv7 instructions are supported
2.) Thumb-2 is unsupported
3.) The code is not SMP safe
We could try to fix this code, but it turns out that because of the above
issues it is rarely used in practice. GDB, for example, uses PTRACE_POKETEXT
and PTRACE_PEEKTEXT to manage breakpoints itself and does not require any
kernel assistance.
This patch removes the single-step emulation code from ptrace meaning that
the PTRACE_SINGLESTEP request will return -EIO on ARM. Portable code must
check the return value from a ptrace call and handle the failure gracefully.
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/ptrace.h')
| -rw-r--r-- | arch/arm/kernel/ptrace.h | 37 |
1 files changed, 0 insertions, 37 deletions
diff --git a/arch/arm/kernel/ptrace.h b/arch/arm/kernel/ptrace.h deleted file mode 100644 index 3926605b82ea..000000000000 --- a/arch/arm/kernel/ptrace.h +++ /dev/null @@ -1,37 +0,0 @@ -/* - * linux/arch/arm/kernel/ptrace.h - * - * Copyright (C) 2000-2003 Russell King - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - */ -#include <linux/ptrace.h> - -extern void ptrace_cancel_bpt(struct task_struct *); -extern void ptrace_set_bpt(struct task_struct *); -extern void ptrace_break(struct task_struct *, struct pt_regs *); - -/* - * Send SIGTRAP if we're single-stepping - */ -static inline void single_step_trap(struct task_struct *task) -{ - if (task->ptrace & PT_SINGLESTEP) { - ptrace_cancel_bpt(task); - send_sig(SIGTRAP, task, 1); - } -} - -static inline void single_step_clear(struct task_struct *task) -{ - if (task->ptrace & PT_SINGLESTEP) - ptrace_cancel_bpt(task); -} - -static inline void single_step_set(struct task_struct *task) -{ - if (task->ptrace & PT_SINGLESTEP) - ptrace_set_bpt(task); -} |