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Subject[RFC PATCH v1 13/13] powerpc/hw_breakpoint: move instruction stepping out of hw_breakpoint_handler()
Date
On 8xx, breakpoints stop after executing the instruction, so
stepping/emulation is not needed. Move it into a sub-function and
remove the #ifdefs.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/kernel/hw_breakpoint.c | 60 ++++++++++++++++++++-----------------
1 file changed, 33 insertions(+), 27 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index b71d3837d673..a6a509b9fd13 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -198,15 +198,43 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
/*
* Handle debug exception notifications.
*/
+static bool stepping_handler(struct pt_regs *regs, struct perf_event *bp,
+ unsigned long addr)
+{
+ int stepped;
+ unsigned int instr;
+
+ /* Do not emulate user-space instructions, instead single-step them */
+ if (user_mode(regs)) {
+ current->thread.last_hit_ubp = bp;
+ regs->msr |= MSR_SE;
+ return false;
+ }
+
+ stepped = 0;
+ instr = 0;
+ if (!__get_user_inatomic(instr, (unsigned int *) regs->nip))
+ stepped = emulate_step(regs, instr);
+
+ /*
+ * emulate_step() could not execute it. We've failed in reliably
+ * handling the hw-breakpoint. Unregister it and throw a warning
+ * message to let the user know about it.
+ */
+ if (!stepped) {
+ WARN(1, "Unable to handle hardware breakpoint. Breakpoint at "
+ "0x%lx will be disabled.", addr);
+ perf_event_disable_inatomic(bp);
+ return false;
+ }
+ return true;
+}
+
int hw_breakpoint_handler(struct die_args *args)
{
int rc = NOTIFY_STOP;
struct perf_event *bp;
struct pt_regs *regs = args->regs;
-#ifndef CONFIG_PPC_8xx
- int stepped = 1;
- unsigned int instr;
-#endif
struct arch_hw_breakpoint *info;
unsigned long dar = regs->dar;

@@ -251,31 +279,9 @@ int hw_breakpoint_handler(struct die_args *args)
(dar - bp->attr.bp_addr < bp->attr.bp_len)))
info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;

-#ifndef CONFIG_PPC_8xx
- /* Do not emulate user-space instructions, instead single-step them */
- if (user_mode(regs)) {
- current->thread.last_hit_ubp = bp;
- regs->msr |= MSR_SE;
+ if (!IS_ENABLED(CONFIG_PPC_8xx) && !stepping_handler(regs, bp, info->address))
goto out;
- }

- stepped = 0;
- instr = 0;
- if (!__get_user_inatomic(instr, (unsigned int *) regs->nip))
- stepped = emulate_step(regs, instr);
-
- /*
- * emulate_step() could not execute it. We've failed in reliably
- * handling the hw-breakpoint. Unregister it and throw a warning
- * message to let the user know about it.
- */
- if (!stepped) {
- WARN(1, "Unable to handle hardware breakpoint. Breakpoint at "
- "0x%lx will be disabled.", info->address);
- perf_event_disable_inatomic(bp);
- goto out;
- }
-#endif
/*
* As a policy, the callback is invoked in a 'trigger-after-execute'
* fashion
--
2.13.3
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