On 1/3/23 2:24 PM, xxmy@xxxxxxxxxxxxx wrote:
From: Tonghao Zhang <xxmy@xxxxxxxxxxxxx>
The x86_64 can't dump the valid insn in this way. A test BPF prog
which include subprog:
$ llvm-objdump -d subprog.o
Disassembly of section .text:
0000000000000000 <subprog>:
0: 18 01 00 00 73 75 62 70 00 00 00 00 72 6f 67 00 r1 = 29114459903653235 ll
2: 7b 1a f8 ff 00 00 00 00 *(u64 *)(r10 - 8) = r1
3: bf a1 00 00 00 00 00 00 r1 = r10
4: 07 01 00 00 f8 ff ff ff r1 += -8
5: b7 02 00 00 08 00 00 00 r2 = 8
6: 85 00 00 00 06 00 00 00 call 6
7: 95 00 00 00 00 00 00 00 exit
Disassembly of section raw_tp/sys_enter:
0000000000000000 <entry>:
0: 85 10 00 00 ff ff ff ff call -1
1: b7 00 00 00 00 00 00 00 r0 = 0
2: 95 00 00 00 00 00 00 00 exit
kernel print message:
[ 580.775387] flen=8 proglen=51 pass=3 image=ffffffffa000c20c from=kprobe-load pid=1643
[ 580.777236] JIT code: 00000000: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
[ 580.779037] JIT code: 00000010: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
[ 580.780767] JIT code: 00000020: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
[ 580.782568] JIT code: 00000030: cc cc cc
$ bpf_jit_disasm
51 bytes emitted from JIT compiler (pass:3, flen:8)
ffffffffa000c20c + <x>:
0: int3
1: int3
2: int3
3: int3
4: int3
5: int3
...
Until bpf_jit_binary_pack_finalize is invoked, we copy rw_header to header
and then image/insn is valid. BTW, we can use the "bpftool prog dump" JITed instructions.
* clean up the doc
* remove bpf_jit_disasm tool
* set bpf_jit_enable only 0 or 1.
Signed-off-by: Tonghao Zhang <xxmy@xxxxxxxxxxxxx>
Suggested-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
Cc: Martin KaFai Lau <martin.lau@xxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: Yonghong Song <yhs@xxxxxx>
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: KP Singh <kpsingh@xxxxxxxxxx>
Cc: Stanislav Fomichev <sdf@xxxxxxxxxx>
Cc: Hao Luo <haoluo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Hou Tao <houtao1@xxxxxxxxxx>
---
Documentation/admin-guide/sysctl/net.rst | 2 +-
Documentation/networking/filter.rst | 98 +------
arch/arm/net/bpf_jit_32.c | 4 -
arch/arm64/net/bpf_jit_comp.c | 4 -
arch/loongarch/net/bpf_jit.c | 4 -
arch/mips/net/bpf_jit_comp.c | 3 -
arch/powerpc/net/bpf_jit_comp.c | 11 -
arch/riscv/net/bpf_jit_core.c | 3 -
arch/s390/net/bpf_jit_comp.c | 4 -
arch/sparc/net/bpf_jit_comp_32.c | 3 -
arch/sparc/net/bpf_jit_comp_64.c | 13 -
arch/x86/net/bpf_jit_comp.c | 3 -
arch/x86/net/bpf_jit_comp32.c | 3 -
net/core/sysctl_net_core.c | 14 +-
tools/bpf/.gitignore | 1 -
tools/bpf/Makefile | 10 +-
tools/bpf/bpf_jit_disasm.c | 332 -----------------------
17 files changed, 8 insertions(+), 504 deletions(-)
delete mode 100644 tools/bpf/bpf_jit_disasm.c
diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst
index 6394f5dc2303..45d3d965276c 100644
--- a/Documentation/admin-guide/sysctl/net.rst
+++ b/Documentation/admin-guide/sysctl/net.rst
@@ -87,7 +87,7 @@ Values:
- 0 - disable the JIT (default value)
- 1 - enable the JIT
- - 2 - enable the JIT and ask the compiler to emit traces on kernel log.
+ - 2 - deprecated in linux 6.2
I'd make it more clear in the docs and reword it as follows (also, it'll be in 6.3, not 6.2):
- 2 - enable the JIT and ask the compiler to emit traces on kernel log.
(deprecated since v6.3, use ``bpftool prog dump jited id <id>`` instead)
bpf_jit_harden
--------------
[...]
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 5b1ce656baa1..731a2eb0f68e 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -275,16 +275,8 @@ static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
tmp.data = &jit_enable;
ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
- if (write && !ret) {
- if (jit_enable < 2 ||
- (jit_enable == 2 && bpf_dump_raw_ok(current_cred()))) {
- *(int *)table->data = jit_enable;
- if (jit_enable == 2)
- pr_warn("bpf_jit_enable = 2 was set! NEVER use this in production, only for JIT debugging!\n");
- } else {
- ret = -EPERM;
- }
- }
+ if (write && !ret)
+ *(int *)table->data = jit_enable;
if (write && ret && min == max)
pr_info_once("CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently set to 1.\n");
@@ -395,7 +387,7 @@ static struct ctl_table net_core_table[] = {
.extra2 = SYSCTL_ONE,
# else
.extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_TWO,
+ .extra2 = SYSCTL_ONE,
I'd leave it at SYSCTL_TWO to avoid breakage, just that the semantics of 2 will be the same
as 1 going forward.
# endif
},
# ifdef CONFIG_HAVE_EBPF_JIT
