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Blackfin: fix single stepping over system calls

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On Blackfin systems, the hardware single step exception triggers before
the system call exception, so we need to save this info to process it
later on.  Otherwise, single stepping in userspace misses a few insns
right after the system call.

This is based a bit on the SuperH code added in commit 4b505db9c4.

Reported-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
This commit is contained in:
Mike Frysinger
2010-02-17 10:44:22 +00:00
parent e8f263dfd3
commit 600482c13d
4 changed files with 15 additions and 3 deletions
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11
arch/blackfin/kernel/ptrace.c
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@@ -220,12 +220,16 @@ void user_enable_single_step(struct task_struct *child)
{
struct pt_regs *regs = task_pt_regs(child);
regs->syscfg |= SYSCFG_SSSTEP;
set_tsk_thread_flag(child, TIF_SINGLESTEP);
}
void user_disable_single_step(struct task_struct *child)
{
struct pt_regs *regs = task_pt_regs(child);
regs->syscfg &= ~SYSCFG_SSSTEP;
clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
@@ -401,6 +405,9 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs)
asmlinkage void syscall_trace_leave(struct pt_regs *regs)
{
if (test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall_exit(regs, 0);
int step;
step = test_thread_flag(TIF_SINGLESTEP);
if (step || test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall_exit(regs, step);
}