From d11a69873d9a7435fe6a48531e165ab80a8b1221 Mon Sep 17 00:00:00 2001 From: Tomislav Novak Date: Mon, 5 Jun 2023 12:19:23 -0700 Subject: hw_breakpoint: fix single-stepping when using bpf_overflow_handler Arm platforms use is_default_overflow_handler() to determine if the hw_breakpoint code should single-step over the breakpoint trigger or let the custom handler deal with it. Since bpf_overflow_handler() currently isn't recognized as a default handler, attaching a BPF program to a PERF_TYPE_BREAKPOINT event causes it to keep firing (the instruction triggering the data abort exception is never skipped). For example: # bpftrace -e 'watchpoint:0x10000:4:w { print("hit") }' -c ./test Attaching 1 probe... hit hit [...] ^C (./test performs a single 4-byte store to 0x10000) This patch replaces the check with uses_default_overflow_handler(), which accounts for the bpf_overflow_handler() case by also testing if one of the perf_event_output functions gets invoked indirectly, via orig_default_handler. Signed-off-by: Tomislav Novak Tested-by: Samuel Gosselin # arm64 Reviewed-by: Catalin Marinas Acked-by: Alexei Starovoitov Link: https://lore.kernel.org/linux-arm-kernel/20220923203644.2731604-1-tnovak@fb.com/ Link: https://lore.kernel.org/r/20230605191923.1219974-1-tnovak@meta.com Signed-off-by: Will Deacon --- arch/arm/kernel/hw_breakpoint.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index 054e9199f30d..dc0fb7a81371 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -626,7 +626,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp, hw->address &= ~alignment_mask; hw->ctrl.len <<= offset; - if (is_default_overflow_handler(bp)) { + if (uses_default_overflow_handler(bp)) { /* * Mismatch breakpoints are required for single-stepping * breakpoints. @@ -798,7 +798,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr, * Otherwise, insert a temporary mismatch breakpoint so that * we can single-step over the watchpoint trigger. */ - if (!is_default_overflow_handler(wp)) + if (!uses_default_overflow_handler(wp)) continue; step: enable_single_step(wp, instruction_pointer(regs)); @@ -811,7 +811,7 @@ step: info->trigger = addr; pr_debug("watchpoint fired: address = 0x%x\n", info->trigger); perf_bp_event(wp, regs); - if (is_default_overflow_handler(wp)) + if (uses_default_overflow_handler(wp)) enable_single_step(wp, instruction_pointer(regs)); } @@ -886,7 +886,7 @@ static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs) info->trigger = addr; pr_debug("breakpoint fired: address = 0x%x\n", addr); perf_bp_event(bp, regs); - if (is_default_overflow_handler(bp)) + if (uses_default_overflow_handler(bp)) enable_single_step(bp, addr); goto unlock; } -- cgit