| Message ID | 20230826053258.1860167-1-hawkinsw@obs.cr (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 2d71a90f7e0fa3cd348602a36f6eb1237ab7cebb |
| Delegated to: | BPF |
| Headers | show |
| Series | bpf, docs: Correct source of offset for program-local call | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
| bpf/vmtest-bpf-next-PR | success | PR summary |
| bpf/vmtest-bpf-next-VM_Test-9 | success | Logs for test_maps on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-8 | success | Logs for test_maps on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-17 | success | Logs for test_progs_no_alu32 on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-18 | success | Logs for test_progs_no_alu32_parallel on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-16 | success | Logs for test_progs_no_alu32 on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-19 | success | Logs for test_progs_no_alu32_parallel on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-20 | success | Logs for test_progs_no_alu32_parallel on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-23 | success | Logs for test_progs_parallel on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-21 | success | Logs for test_progs_parallel on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-22 | success | Logs for test_progs_parallel on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-24 | success | Logs for test_verifier on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-26 | success | Logs for test_verifier on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-27 | success | Logs for test_verifier on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-28 | success | Logs for veristat |
| bpf/vmtest-bpf-next-VM_Test-10 | success | Logs for test_progs on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-13 | success | Logs for test_progs on x86_64 with llvm-16 |
| bpf/vmtest-bpf-next-VM_Test-12 | success | Logs for test_progs on x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-14 | success | Logs for test_progs_no_alu32 on aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-25 | success | Logs for test_verifier on s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-15 | success | Logs for test_progs_no_alu32 on s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-11 | success | Logs for test_progs on s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-0 | success | Logs for ${{ matrix.test }} on ${{ matrix.arch }} with ${{ matrix.toolchain_full }} |
| bpf/vmtest-bpf-next-VM_Test-1 | success | Logs for ShellCheck |
| bpf/vmtest-bpf-next-VM_Test-2 | success | Logs for build for aarch64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-4 | success | Logs for build for x86_64 with gcc |
| bpf/vmtest-bpf-next-VM_Test-3 | fail | Logs for build for s390x with gcc |
| bpf/vmtest-bpf-next-VM_Test-7 | success | Logs for veristat |
| bpf/vmtest-bpf-next-VM_Test-6 | success | Logs for set-matrix |
| bpf/vmtest-bpf-next-VM_Test-5 | success | Logs for build for x86_64 with llvm-16 |
On Sat, 2023-08-26 at 01:32 -0400, Will Hawkins wrote: > The offset to use when calculating the target of a program-local call is > in the instruction's imm field, not its offset field. Indeed, this is the case, e.g. see kernel/bpf/verifier.c:add_subprog_and_kfunc(). Acked-by: Eduard Zingerman <eddyz87@gmail.com> > > Signed-off-by: Will Hawkins <hawkinsw@obs.cr> > --- > Documentation/bpf/standardization/instruction-set.rst | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/Documentation/bpf/standardization/instruction-set.rst b/Documentation/bpf/standardization/instruction-set.rst > index 4f73e9dc8d9e..c5b0b2011f16 100644 > --- a/Documentation/bpf/standardization/instruction-set.rst > +++ b/Documentation/bpf/standardization/instruction-set.rst > @@ -373,7 +373,7 @@ BPF_JNE 0x5 any PC += offset if dst != src > BPF_JSGT 0x6 any PC += offset if dst > src signed > BPF_JSGE 0x7 any PC += offset if dst >= src signed > BPF_CALL 0x8 0x0 call helper function by address see `Helper functions`_ > -BPF_CALL 0x8 0x1 call PC += offset see `Program-local functions`_ > +BPF_CALL 0x8 0x1 call PC += imm see `Program-local functions`_ > BPF_CALL 0x8 0x2 call helper function by BTF ID see `Helper functions`_ > BPF_EXIT 0x9 0x0 return BPF_JMP only > BPF_JLT 0xa any PC += offset if dst < src unsigned > @@ -424,8 +424,8 @@ Program-local functions > ~~~~~~~~~~~~~~~~~~~~~~~ > Program-local functions are functions exposed by the same BPF program as the > caller, and are referenced by offset from the call instruction, similar to > -``BPF_JA``. A ``BPF_EXIT`` within the program-local function will return to > -the caller. > +``BPF_JA``. The offset is encoded in the imm field of the call instruction. > +A ``BPF_EXIT`` within the program-local function will return to the caller. > > Load and store instructions > ===========================
On Sat, Aug 26, 2023 at 01:32:54AM -0400, Will Hawkins wrote: > The offset to use when calculating the target of a program-local call is > in the instruction's imm field, not its offset field. > > Signed-off-by: Will Hawkins <hawkinsw@obs.cr> LGTM, thanks for the fix. Acked-by: David Vernet <void@manifault.com>
Hello: This patch was applied to bpf/bpf.git (master) by Daniel Borkmann <daniel@iogearbox.net>: On Sat, 26 Aug 2023 01:32:54 -0400 you wrote: > The offset to use when calculating the target of a program-local call is > in the instruction's imm field, not its offset field. > > Signed-off-by: Will Hawkins <hawkinsw@obs.cr> > --- > Documentation/bpf/standardization/instruction-set.rst | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) Here is the summary with links: - bpf, docs: Correct source of offset for program-local call https://git.kernel.org/bpf/bpf/c/2d71a90f7e0f You are awesome, thank you!
diff --git a/Documentation/bpf/standardization/instruction-set.rst b/Documentation/bpf/standardization/instruction-set.rst index 4f73e9dc8d9e..c5b0b2011f16 100644 --- a/Documentation/bpf/standardization/instruction-set.rst +++ b/Documentation/bpf/standardization/instruction-set.rst @@ -373,7 +373,7 @@ BPF_JNE 0x5 any PC += offset if dst != src BPF_JSGT 0x6 any PC += offset if dst > src signed BPF_JSGE 0x7 any PC += offset if dst >= src signed BPF_CALL 0x8 0x0 call helper function by address see `Helper functions`_ -BPF_CALL 0x8 0x1 call PC += offset see `Program-local functions`_ +BPF_CALL 0x8 0x1 call PC += imm see `Program-local functions`_ BPF_CALL 0x8 0x2 call helper function by BTF ID see `Helper functions`_ BPF_EXIT 0x9 0x0 return BPF_JMP only BPF_JLT 0xa any PC += offset if dst < src unsigned @@ -424,8 +424,8 @@ Program-local functions ~~~~~~~~~~~~~~~~~~~~~~~ Program-local functions are functions exposed by the same BPF program as the caller, and are referenced by offset from the call instruction, similar to -``BPF_JA``. A ``BPF_EXIT`` within the program-local function will return to -the caller. +``BPF_JA``. The offset is encoded in the imm field of the call instruction. +A ``BPF_EXIT`` within the program-local function will return to the caller. Load and store instructions ===========================
The offset to use when calculating the target of a program-local call is in the instruction's imm field, not its offset field. Signed-off-by: Will Hawkins <hawkinsw@obs.cr> --- Documentation/bpf/standardization/instruction-set.rst | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)