From mboxrd@z Thu Jan 1 00:00:00 1970 From: dave.long@linaro.org (David Long) Date: Tue, 6 Sep 2016 17:36:18 -0400 Subject: [PATCH 3/5] arm64: Handle TRAP_HWBRKPT for user mode as well In-Reply-To: <20160906161139.GG19605@e104818-lin.cambridge.arm.com> References: <20160906161139.GG19605@e104818-lin.cambridge.arm.com> Message-ID: <57CF36D2.4010404@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 09/06/2016 12:11 PM, Catalin Marinas wrote: > On Tue, Aug 02, 2016 at 11:00:07AM +0530, Pratyush Anand wrote: >> --- a/arch/arm64/kernel/debug-monitors.c >> +++ b/arch/arm64/kernel/debug-monitors.c >> @@ -246,6 +246,8 @@ static void send_user_sigtrap(int si_code) >> static int single_step_handler(unsigned long addr, unsigned int esr, >> struct pt_regs *regs) >> { >> + bool handler_found = false; >> + >> /* >> * If we are stepping a pending breakpoint, call the hw_breakpoint >> * handler first. >> @@ -253,7 +255,14 @@ static int single_step_handler(unsigned long addr, unsigned int esr, >> if (!reinstall_suspended_bps(regs)) >> return 0; >> >> - if (user_mode(regs)) { >> +#ifdef CONFIG_KPROBES >> + if (kprobe_single_step_handler(regs, esr) == DBG_HOOK_HANDLED) >> + handler_found = true; >> +#endif >> + if (!handler_found && call_step_hook(regs, esr) == DBG_HOOK_HANDLED) >> + handler_found = true; >> + >> + if (!handler_found && user_mode(regs)) { >> send_user_sigtrap(TRAP_HWBKPT); > > Could we register kprobe_single_step_handler() via register_set_hook() > and only invoke call_step_hook() above? > I seem to recall a criticism of doing that in a much earlier kprobes64 patch of mine. The concern was that it would cause unnecessarily more kernel functions to be kprobes-blacklisted. Hence the hardcoded check and call. -dl