From 658d029df0bce6472c94b724ca54d74bc6659c2e Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Fri, 28 Jun 2019 15:55:52 +0000 Subject: [PATCH] powerpc/hw_breakpoint: move instruction stepping out of hw_breakpoint_handler() 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 Reviewed-by: Ravi Bangoria Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/f8cdc3f1c66ad3c43ebc568abcc6c39ed4676284.1561737231.git.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 c8d1fa2e9d53..28ad3171bb82 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; @@ -251,32 +279,10 @@ 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 */ -- 2.11.0