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hw_breakpoint: fix single-stepping when using bpf_overflow_handler
[ Upstream commit d11a69873d
]
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@meta.com>
Tested-by: Samuel Gosselin <sgosselin@google.com> # arm64
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
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 <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
1ffd7e7e23
commit
4252c35010
3 changed files with 25 additions and 9 deletions
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@ -631,7 +631,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
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info->address &= ~alignment_mask;
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info->ctrl.len <<= offset;
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if (is_default_overflow_handler(bp)) {
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if (uses_default_overflow_handler(bp)) {
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/*
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* Mismatch breakpoints are required for single-stepping
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* breakpoints.
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@ -803,7 +803,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr,
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* Otherwise, insert a temporary mismatch breakpoint so that
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* we can single-step over the watchpoint trigger.
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*/
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if (!is_default_overflow_handler(wp))
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if (!uses_default_overflow_handler(wp))
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continue;
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step:
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enable_single_step(wp, instruction_pointer(regs));
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@ -816,7 +816,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr,
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info->trigger = addr;
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pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
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perf_bp_event(wp, regs);
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if (is_default_overflow_handler(wp))
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if (uses_default_overflow_handler(wp))
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enable_single_step(wp, instruction_pointer(regs));
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}
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@ -891,7 +891,7 @@ static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
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info->trigger = addr;
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pr_debug("breakpoint fired: address = 0x%x\n", addr);
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perf_bp_event(bp, regs);
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if (is_default_overflow_handler(bp))
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if (uses_default_overflow_handler(bp))
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enable_single_step(bp, addr);
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goto unlock;
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}
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@ -662,7 +662,7 @@ static int breakpoint_handler(unsigned long unused, unsigned int esr,
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perf_bp_event(bp, regs);
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/* Do we need to handle the stepping? */
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if (is_default_overflow_handler(bp))
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if (uses_default_overflow_handler(bp))
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step = 1;
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unlock:
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rcu_read_unlock();
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@ -741,7 +741,7 @@ static u64 get_distance_from_watchpoint(unsigned long addr, u64 val,
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static int watchpoint_report(struct perf_event *wp, unsigned long addr,
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struct pt_regs *regs)
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{
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int step = is_default_overflow_handler(wp);
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int step = uses_default_overflow_handler(wp);
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struct arch_hw_breakpoint *info = counter_arch_bp(wp);
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info->trigger = addr;
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@ -985,15 +985,31 @@ extern void perf_event_output(struct perf_event *event,
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struct pt_regs *regs);
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static inline bool
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is_default_overflow_handler(struct perf_event *event)
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__is_default_overflow_handler(perf_overflow_handler_t overflow_handler)
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{
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if (likely(event->overflow_handler == perf_event_output_forward))
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if (likely(overflow_handler == perf_event_output_forward))
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return true;
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if (unlikely(event->overflow_handler == perf_event_output_backward))
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if (unlikely(overflow_handler == perf_event_output_backward))
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return true;
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return false;
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}
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#define is_default_overflow_handler(event) \
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__is_default_overflow_handler((event)->overflow_handler)
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#ifdef CONFIG_BPF_SYSCALL
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static inline bool uses_default_overflow_handler(struct perf_event *event)
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{
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if (likely(is_default_overflow_handler(event)))
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return true;
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return __is_default_overflow_handler(event->orig_overflow_handler);
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}
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#else
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#define uses_default_overflow_handler(event) \
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is_default_overflow_handler(event)
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#endif
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extern void
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perf_event_header__init_id(struct perf_event_header *header,
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struct perf_sample_data *data,
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