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bpf: Adjust kprobe_multi entry_ip for CONFIG_X86_KERNEL_IBT
[ Upstream commitc09eb2e578
] Martynas reported bpf_get_func_ip returning +4 address when CONFIG_X86_KERNEL_IBT option is enabled. When CONFIG_X86_KERNEL_IBT is enabled we'll have endbr instruction at the function entry, which screws return value of bpf_get_func_ip() helper that should return the function address. There's short term workaround for kprobe_multi bpf program made by Alexei [1], but we need this fixup also for bpf_get_attach_cookie, that returns cookie based on the entry_ip value. Moving the fixup in the fprobe handler, so both bpf_get_func_ip and bpf_get_attach_cookie get expected function address when CONFIG_X86_KERNEL_IBT option is enabled. Also renaming kprobe_multi_link_handler entry_ip argument to fentry_ip so it's clearer this is an ftrace __fentry__ ip. [1] commit7f0059b58f
("selftests/bpf: Fix kprobe_multi test.") Cc: Peter Zijlstra <peterz@infradead.org> Reported-by: Martynas Pumputis <m@lambda.lt> Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20220926153340.1621984-5-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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parent
435f5aa442
commit
03f148c159
2 changed files with 19 additions and 5 deletions
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@ -1026,6 +1026,22 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_tracing = {
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.arg1_type = ARG_PTR_TO_CTX,
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.arg1_type = ARG_PTR_TO_CTX,
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};
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};
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#ifdef CONFIG_X86_KERNEL_IBT
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static unsigned long get_entry_ip(unsigned long fentry_ip)
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{
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u32 instr;
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/* Being extra safe in here in case entry ip is on the page-edge. */
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if (get_kernel_nofault(instr, (u32 *) fentry_ip - 1))
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return fentry_ip;
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if (is_endbr(instr))
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fentry_ip -= ENDBR_INSN_SIZE;
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return fentry_ip;
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}
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#else
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#define get_entry_ip(fentry_ip) fentry_ip
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#endif
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BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
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BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
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{
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{
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struct kprobe *kp = kprobe_running();
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struct kprobe *kp = kprobe_running();
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@ -2414,13 +2430,13 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
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}
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}
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static void
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static void
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kprobe_multi_link_handler(struct fprobe *fp, unsigned long entry_ip,
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kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
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struct pt_regs *regs)
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struct pt_regs *regs)
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{
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{
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struct bpf_kprobe_multi_link *link;
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struct bpf_kprobe_multi_link *link;
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link = container_of(fp, struct bpf_kprobe_multi_link, fp);
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link = container_of(fp, struct bpf_kprobe_multi_link, fp);
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kprobe_multi_link_prog_run(link, entry_ip, regs);
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kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
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}
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}
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static int symbols_cmp_r(const void *a, const void *b, const void *priv)
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static int symbols_cmp_r(const void *a, const void *b, const void *priv)
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@ -36,15 +36,13 @@ __u64 kretprobe_test6_result = 0;
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__u64 kretprobe_test7_result = 0;
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__u64 kretprobe_test7_result = 0;
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__u64 kretprobe_test8_result = 0;
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__u64 kretprobe_test8_result = 0;
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extern bool CONFIG_X86_KERNEL_IBT __kconfig __weak;
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static void kprobe_multi_check(void *ctx, bool is_return)
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static void kprobe_multi_check(void *ctx, bool is_return)
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{
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{
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if (bpf_get_current_pid_tgid() >> 32 != pid)
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if (bpf_get_current_pid_tgid() >> 32 != pid)
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return;
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return;
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__u64 cookie = test_cookie ? bpf_get_attach_cookie(ctx) : 0;
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__u64 cookie = test_cookie ? bpf_get_attach_cookie(ctx) : 0;
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__u64 addr = bpf_get_func_ip(ctx) - (CONFIG_X86_KERNEL_IBT ? 4 : 0);
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__u64 addr = bpf_get_func_ip(ctx);
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#define SET(__var, __addr, __cookie) ({ \
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#define SET(__var, __addr, __cookie) ({ \
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if (((const void *) addr == __addr) && \
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if (((const void *) addr == __addr) && \
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