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powerpc/hw_breakpoint: move instruction stepping out of hw_breakpoint_handler()

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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>
Reviewed-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f8cdc3f1c66ad3c43ebc568abcc6c39ed4676284.1561737231.git.christophe.leroy@c-s.fr
This commit is contained in:
Christophe Leroy 2019-06-28 15:55:52 +00:00 committed by Michael Ellerman
parent 65e701b2d2
commit 658d029df0
1 changed files with 33 additions and 27 deletions
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60
arch/powerpc/kernel/hw_breakpoint.c
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@ -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