Patch "hw_breakpoint: fix single-stepping when using bpf_overflow_handler" has been added to the 6.5-stable tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



This is a note to let you know that I've just added the patch titled

    hw_breakpoint: fix single-stepping when using bpf_overflow_handler

to the 6.5-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     hw_breakpoint-fix-single-stepping-when-using-bpf_ove.patch
and it can be found in the queue-6.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 579f7fbb827f60efe1e46a663b5803d61b534523
Author: Tomislav Novak <tnovak@xxxxxxxx>
Date:   Mon Jun 5 12:19:23 2023 -0700

    hw_breakpoint: fix single-stepping when using bpf_overflow_handler
    
    [ Upstream commit d11a69873d9a7435fe6a48531e165ab80a8b1221 ]
    
    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 <tnovak@xxxxxxxx>
    Tested-by: Samuel Gosselin <sgosselin@xxxxxxxxxx> # arm64
    Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
    Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>
    Link: https://lore.kernel.org/linux-arm-kernel/20220923203644.2731604-1-tnovak@xxxxxx/
    Link: https://lore.kernel.org/r/20230605191923.1219974-1-tnovak@xxxxxxxx
    Signed-off-by: Will Deacon <will@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 054e9199f30db..dc0fb7a813715 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 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr,
 		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;
 		}
diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
index db2a1861bb978..35225632d70ad 100644
--- a/arch/arm64/kernel/hw_breakpoint.c
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -654,7 +654,7 @@ static int breakpoint_handler(unsigned long unused, unsigned long esr,
 		perf_bp_event(bp, regs);
 
 		/* Do we need to handle the stepping? */
-		if (is_default_overflow_handler(bp))
+		if (uses_default_overflow_handler(bp))
 			step = 1;
 unlock:
 		rcu_read_unlock();
@@ -733,7 +733,7 @@ static u64 get_distance_from_watchpoint(unsigned long addr, u64 val,
 static int watchpoint_report(struct perf_event *wp, unsigned long addr,
 			     struct pt_regs *regs)
 {
-	int step = is_default_overflow_handler(wp);
+	int step = uses_default_overflow_handler(wp);
 	struct arch_hw_breakpoint *info = counter_arch_bp(wp);
 
 	info->trigger = addr;
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2166a69e3bf2e..e657916c9509c 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1316,15 +1316,31 @@ extern int perf_event_output(struct perf_event *event,
 			     struct pt_regs *regs);
 
 static inline bool
-is_default_overflow_handler(struct perf_event *event)
+__is_default_overflow_handler(perf_overflow_handler_t overflow_handler)
 {
-	if (likely(event->overflow_handler == perf_event_output_forward))
+	if (likely(overflow_handler == perf_event_output_forward))
 		return true;
-	if (unlikely(event->overflow_handler == perf_event_output_backward))
+	if (unlikely(overflow_handler == perf_event_output_backward))
 		return true;
 	return false;
 }
 
+#define is_default_overflow_handler(event) \
+	__is_default_overflow_handler((event)->overflow_handler)
+
+#ifdef CONFIG_BPF_SYSCALL
+static inline bool uses_default_overflow_handler(struct perf_event *event)
+{
+	if (likely(is_default_overflow_handler(event)))
+		return true;
+
+	return __is_default_overflow_handler(event->orig_overflow_handler);
+}
+#else
+#define uses_default_overflow_handler(event) \
+	is_default_overflow_handler(event)
+#endif
+
 extern void
 perf_event_header__init_id(struct perf_event_header *header,
 			   struct perf_sample_data *data,



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux