2013-04-21 16:51:12

by Oleg Nesterov

[permalink] [raw]
Subject: [PATCH] ptrace/powerpc: dont flush_ptrace_hw_breakpoint() on fork()

arch_dup_task_struct() does flush_ptrace_hw_breakpoint(src), this
destroys the parent's breakpoints for no reason. We should clear
child->thread.ptrace_bps[] copied by dup_task_struct() instead.

Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Michael Neuling <[email protected]>

--- x/arch/powerpc/kernel/process.c
+++ x/arch/powerpc/kernel/process.c
@@ -910,10 +910,6 @@ int arch_dup_task_struct(struct task_str
flush_altivec_to_thread(src);
flush_vsx_to_thread(src);
flush_spe_to_thread(src);
-#ifdef CONFIG_HAVE_HW_BREAKPOINT
- flush_ptrace_hw_breakpoint(src);
-#endif /* CONFIG_HAVE_HW_BREAKPOINT */
-
*dst = *src;
return 0;
}
@@ -984,6 +980,10 @@ int copy_thread(unsigned long clone_flag
p->thread.ksp_limit = (unsigned long)task_stack_page(p) +
_ALIGN_UP(sizeof(struct thread_info), 16);

+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ p->thread.ptrace_bps[0] = NULL;
+#endif
+
#ifdef CONFIG_PPC_STD_MMU_64
if (mmu_has_feature(MMU_FTR_SLB)) {
unsigned long sp_vsid;