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ptrace: arch_has_block_step

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This defines the new macro arch_has_block_step() in linux/ptrace.h, a
default for when asm/ptrace.h does not define it.  This is the analog
of arch_has_single_step() for step-until-branch on machines that have
it.  It declares the new user_enable_block_step function, which goes
with the existing user_enable_single_step and user_disable_single_step.
This is not used yet, but paves the way to harmonize on this interface
for the arch-specific calls on all machines.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Roland McGrath 2008-01-30 13:30:53 +01:00 committed by Ingo Molnar
parent d9771e8c50
commit dc802c2d2e
1 changed files with 33 additions and 4 deletions
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37
include/linux/ptrace.h
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@ -155,7 +155,8 @@ int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data);
*
* This can only be called when arch_has_single_step() has returned nonzero.
* Set @task so that when it returns to user mode, it will trap after the
* next single instruction executes.
* next single instruction executes. If arch_has_block_step() is defined,
* this must clear the effects of user_enable_block_step() too.
*/
static inline void user_enable_single_step(struct task_struct *task)
{
@ -166,15 +167,43 @@ static inline void user_enable_single_step(struct task_struct *task)
* user_disable_single_step - cancel user-mode single-step
* @task: either current or a task stopped in %TASK_TRACED
*
* Clear @task of the effects of user_enable_single_step(). This can
* be called whether or not user_enable_single_step() was ever called
* on @task, and even if arch_has_single_step() returned zero.
* Clear @task of the effects of user_enable_single_step() and
* user_enable_block_step(). This can be called whether or not either
* of those was ever called on @task, and even if arch_has_single_step()
* returned zero.
*/
static inline void user_disable_single_step(struct task_struct *task)
{
}
#endif /* arch_has_single_step */
#ifndef arch_has_block_step
/**
* arch_has_block_step - does this CPU support user-mode block-step?
*
* If this is defined, then there must be a function declaration or inline
* for user_enable_block_step(), and arch_has_single_step() must be defined
* too. arch_has_block_step() should evaluate to nonzero iff the machine
* supports step-until-branch for user mode. It can be a constant or it
* can test a CPU feature bit.
*/
#define arch_has_single_step() (0)
/**
* user_enable_block_step - step until branch in user-mode task
* @task: either current or a task stopped in %TASK_TRACED
*
* This can only be called when arch_has_block_step() has returned nonzero,
* and will never be called when single-instruction stepping is being used.
* Set @task so that when it returns to user mode, it will trap after the
* next branch or trap taken.
*/
static inline void user_enable_block_step(struct task_struct *task)
{
BUG(); /* This can never be called. */
}
#endif /* arch_has_block_step */
#endif
#endif