Re: [PATCH] perf probe: Fix kprobe blacklist checking condition

From: Arnaldo Carvalho de Melo
Date: Tue Aug 29 2017 - 10:51:19 EST


Em Tue, Aug 29, 2017 at 08:57:23PM +0800, Li Bin escreveu:
> The commit 9aaf5a5("perf probe: Check kprobes blacklist
> when adding new events"), perf probe supports checking
> the blacklist of the fuctions which can not be probed.
> But the checking condition is wrong, that the end_addr
> of the symbol which is the start_addr of the next symbol
> can't be included.

Applied, with the following committer notes added:

Committer notes:

IOW make it match its kernel counterpart in kernel/kprobes.c:

bool within_kprobe_blacklist(unsigned long addr)

Each entry have as its end address not its end address, but the first
address _outside_ that symbol, which for related functions, is the first
address of the next symbol, like these from kernel/trace/trace_probe.c:

0xffffffffbd198df0-0xffffffffbd198e40 print_type_u8
0xffffffffbd198e40-0xffffffffbd198e90 print_type_u16
0xffffffffbd198e90-0xffffffffbd198ee0 print_type_u32
0xffffffffbd198ee0-0xffffffffbd198f30 print_type_u64
0xffffffffbd198f30-0xffffffffbd198f80 print_type_s8
0xffffffffbd198f80-0xffffffffbd198fd0 print_type_s16
0xffffffffbd198fd0-0xffffffffbd199020 print_type_s32
0xffffffffbd199020-0xffffffffbd199070 print_type_s64
0xffffffffbd199070-0xffffffffbd1990c0 print_type_x8
0xffffffffbd1990c0-0xffffffffbd199110 print_type_x16
0xffffffffbd199110-0xffffffffbd199160 print_type_x32
0xffffffffbd199160-0xffffffffbd1991b0 print_type_x64

But not always:

0xffffffffbd1997b0-0xffffffffbd1997c0 fetch_kernel_stack_address (kernel/trace/trace_probe.c)
0xffffffffbd1c57f0-0xffffffffbd1c58b0 __context_tracking_enter (kernel/context_tracking.c)

Fixes: 9aaf5a5f479b ("perf probe: Check kprobes blacklist when adding new events")