From a22d570aee77ae626e4d3532478ae8058a24bdb3 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 26 Feb 2019 14:35:00 +0000 Subject: arm64: kprobes: Avoid calling kprobes debug handlers explicitly Kprobes bypasses our debug hook registration code so that it doesn't get tangled up with recursive debug exceptions from things like lockdep: http://lists.infradead.org/pipermail/linux-arm-kernel/2015-February/324385.html However, since then, (a) the hook list has become RCU protected and (b) the kprobes hooks were found not to filter out exceptions from userspace correctly. On top of that, the step handler is invoked directly from single_step_handler(), which *does* use the debug hook list, so it's clearly not the end of the world. For now, have kprobes use the debug hook registration API like everybody else. We can revisit this in the future if this is found to limit coverage significantly. Reviewed-by: Mark Rutland Signed-off-by: Will Deacon --- arch/arm64/kernel/debug-monitors.c | 10 ---------- 1 file changed, 10 deletions(-) (limited to 'arch/arm64/kernel/debug-monitors.c') diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index 9b3fd7fa5b43..f4d8cda8830d 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -258,10 +258,6 @@ static int single_step_handler(unsigned long unused, unsigned int esr, if (!reinstall_suspended_bps(regs)) return 0; -#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; @@ -337,12 +333,6 @@ static int brk_handler(unsigned long unused, unsigned int esr, { bool handler_found = false; -#ifdef CONFIG_KPROBES - if ((esr & BRK64_ESR_MASK) == BRK64_ESR_KPROBES) { - if (kprobe_breakpoint_handler(regs, esr) == DBG_HOOK_HANDLED) - handler_found = true; - } -#endif if (!handler_found && call_break_hook(regs, esr) == DBG_HOOK_HANDLED) handler_found = true; -- cgit v1.2.3