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| author | Daniel T. Lee <danieltimlee@gmail.com> | 2020-07-07 21:48:52 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-07-08 02:32:14 +0300 |
| commit | af9bd3e3331b8af42b6606c75797d041ab39380c (patch) | |
| tree | e4912c10f7f5680424b6d48fbfa0c0c5c98f20ba /samples/bpf/map_perf_test_kern.c | |
| parent | 65ffd797861a44ff97081de1db01e4aef716ed46 (diff) | |
| download | linux-af9bd3e3331b8af42b6606c75797d041ab39380c.tar.xz | |
samples: bpf: Fix bpf programs with kprobe/sys_connect event
Currently, BPF programs with kprobe/sys_connect does not work properly.
Commit 34745aed515c ("samples/bpf: fix kprobe attachment issue on x64")
This commit modifies the bpf_load behavior of kprobe events in the x64
architecture. If the current kprobe event target starts with "sys_*",
add the prefix "__x64_" to the front of the event.
Appending "__x64_" prefix with kprobe/sys_* event was appropriate as a
solution to most of the problems caused by the commit below.
commit d5a00528b58c ("syscalls/core, syscalls/x86: Rename struct
pt_regs-based sys_*() to __x64_sys_*()")
However, there is a problem with the sys_connect kprobe event that does
not work properly. For __sys_connect event, parameters can be fetched
normally, but for __x64_sys_connect, parameters cannot be fetched.
ffffffff818d3520 <__x64_sys_connect>:
ffffffff818d3520: e8 fb df 32 00 callq 0xffffffff81c01520
<__fentry__>
ffffffff818d3525: 48 8b 57 60 movq 96(%rdi), %rdx
ffffffff818d3529: 48 8b 77 68 movq 104(%rdi), %rsi
ffffffff818d352d: 48 8b 7f 70 movq 112(%rdi), %rdi
ffffffff818d3531: e8 1a ff ff ff callq 0xffffffff818d3450
<__sys_connect>
ffffffff818d3536: 48 98 cltq
ffffffff818d3538: c3 retq
ffffffff818d3539: 0f 1f 80 00 00 00 00 nopl (%rax)
As the assembly code for __x64_sys_connect shows, parameters should be
fetched and set into rdi, rsi, rdx registers prior to calling
__sys_connect.
Because of this problem, this commit fixes the sys_connect event by
first getting the value of the rdi register and then the value of the
rdi, rsi, and rdx register through an offset based on that value.
Fixes: 34745aed515c ("samples/bpf: fix kprobe attachment issue on x64")
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200707184855.30968-2-danieltimlee@gmail.com
Diffstat (limited to 'samples/bpf/map_perf_test_kern.c')
| -rw-r--r-- | samples/bpf/map_perf_test_kern.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/samples/bpf/map_perf_test_kern.c b/samples/bpf/map_perf_test_kern.c index 12e91ae64d4d..c9b31193ca12 100644 --- a/samples/bpf/map_perf_test_kern.c +++ b/samples/bpf/map_perf_test_kern.c @@ -11,6 +11,8 @@ #include <bpf/bpf_helpers.h> #include "bpf_legacy.h" #include <bpf/bpf_tracing.h> +#include <bpf/bpf_core_read.h> +#include "trace_common.h" #define MAX_ENTRIES 1000 #define MAX_NR_CPUS 1024 @@ -154,9 +156,10 @@ int stress_percpu_hmap_alloc(struct pt_regs *ctx) return 0; } -SEC("kprobe/sys_connect") +SEC("kprobe/" SYSCALL(sys_connect)) int stress_lru_hmap_alloc(struct pt_regs *ctx) { + struct pt_regs *real_regs = (struct pt_regs *)PT_REGS_PARM1_CORE(ctx); char fmt[] = "Failed at stress_lru_hmap_alloc. ret:%dn"; union { u16 dst6[8]; @@ -175,8 +178,8 @@ int stress_lru_hmap_alloc(struct pt_regs *ctx) long val = 1; u32 key = 0; - in6 = (struct sockaddr_in6 *)PT_REGS_PARM2(ctx); - addrlen = (int)PT_REGS_PARM3(ctx); + in6 = (struct sockaddr_in6 *)PT_REGS_PARM2_CORE(real_regs); + addrlen = (int)PT_REGS_PARM3_CORE(real_regs); if (addrlen != sizeof(*in6)) return 0; |