Yazhou Tang says:
====================
bpf: Add range tracking for BPF_DIV and BPF_MOD
From: Yazhou Tang <tangyazhou518@outlook.com>
Add range tracking (interval analysis) for BPF_DIV and BPF_MOD when
divisor is constant. Please see commit log of 1/2 for more details.
Changes v4 => v5:
1. Rename helper functions `__reset_reg(32|64)_and_tnum` to
`reset_reg(32|64)_and_tnum`. (Alexei)
2. Replace plain C division with `div64_u64` and `div64_s64` for 64-bit
operations, ensuring compatibility with 32-bit architectures. (Alexei
& kernel test robot)
3. Fixup an indent typo in selftest file `verifier_div_mod_bounds.c`.
v4: https://lore.kernel.org/bpf/20260116103246.2477635-1-tangyazhou@zju.edu.cn/
Changes v3 => v4:
1. Remove verbose helper functions for "division by zero" handling. (Alexei)
2. Put all "reset" logic in one place for clarity, and add 2 helper
function `__reset_reg64_and_tnum` and `__reset_reg32_and_tnum` to
reduce code duplication. (Alexei)
3. Update all multi-line comments to follow the standard kernel style. (Alexei)
4. Add new test cases to cover strictly positive and strictly negative
divisor scenarios in SDIV and SMOD analysis. (Alexei)
5. Fixup a typo in SDIV analysis functions.
v3: https://lore.kernel.org/bpf/20260113103552.3435695-1-tangyazhou@zju.edu.cn/
Changes v2 => v3:
1. Fixup a bug in `adjust_scalar_min_max_vals` function that lead to
incorrect range results. (Syzbot)
2. Remove tnum analysis logic. (Alexei)
3. Only handle "constant divisor" case. (Alexei)
4. Add BPF_MOD range analysis logic.
5. Update selftests accordingly.
6. Add detailed code comments and improve commit messages. (Yonghong)
v2: https://lore.kernel.org/bpf/20251223091120.2413435-1-tangyazhou@zju.edu.cn/
Changes v1 => v2:
1. Fixed 2 bugs in sdiv32 analysis logic and corrected the associated
selftest cases. (AI reviewer)
2. Renamed `tnum_bottom` to `tnum_empty` for better clarity, and updated
commit message to explain its role in signed BPF_DIV analysis.
v1:
https://lore.kernel.org/bpf/tencent_717092CD734D050CCD93401CA624BB3C8307@qq.com/https://lore.kernel.org/bpf/tencent_7C98FAECA40C98489ACF4515CE346F031509@qq.com/
====================
Link: https://patch.msgid.link/20260119085458.182221-1-tangyazhou@zju.edu.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Now BPF_DIV has range tracking support via interval analysis. This patch
adds selftests to cover various cases of BPF_DIV and BPF_MOD operations
when the divisor is a constant, also covering both signed and unsigned variants.
This patch includes several types of tests in 32-bit and 64-bit variants:
1. For UDIV
- positive divisor
- zero divisor
2. For SDIV
- positive divisor, positive dividend
- positive divisor, negative dividend
- positive divisor, mixed sign dividend
- negative divisor, positive dividend
- negative divisor, negative dividend
- negative divisor, mixed sign dividend
- zero divisor
- overflow (SIGNED_MIN/-1), normal dividend
- overflow (SIGNED_MIN/-1), constant dividend
3. For UMOD
- positive divisor
- positive divisor, small dividend
- zero divisor
4. For SMOD
- positive divisor, positive dividend
- positive divisor, negative dividend
- positive divisor, mixed sign dividend
- positive divisor, mixed sign dividend, small dividend
- negative divisor, positive dividend
- negative divisor, negative dividend
- negative divisor, mixed sign dividend
- negative divisor, mixed sign dividend, small dividend
- zero divisor
- overflow (SIGNED_MIN/-1), normal dividend
- overflow (SIGNED_MIN/-1), constant dividend
Specifically, these selftests are based on dead code elimination:
If the BPF verifier can precisely analyze the result of BPF_DIV/BPF_MOD
instruction, it can prune the path that leads to an error (here we use
invalid memory access as the error case), allowing the program to pass
verification.
Co-developed-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Co-developed-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Yazhou Tang <tangyazhou518@outlook.com>
Link: https://lore.kernel.org/r/20260119085458.182221-3-tangyazhou@zju.edu.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch implements range tracking (interval analysis) for BPF_DIV and
BPF_MOD operations when the divisor is a constant, covering both signed
and unsigned variants.
While LLVM typically optimizes integer division and modulo by constants
into multiplication and shift sequences, this optimization is less
effective for the BPF target when dealing with 64-bit arithmetic.
Currently, the verifier does not track bounds for scalar division or
modulo, treating the result as "unbounded". This leads to false positive
rejections for safe code patterns.
For example, the following code (compiled with -O2):
```c
int test(struct pt_regs *ctx) {
char buffer[6] = {1};
__u64 x = bpf_ktime_get_ns();
__u64 res = x % sizeof(buffer);
char value = buffer[res];
bpf_printk("res = %llu, val = %d", res, value);
return 0;
}
```
Generates a raw `BPF_MOD64` instruction:
```asm
; __u64 res = x % sizeof(buffer);
1: 97 00 00 00 06 00 00 00 r0 %= 0x6
; char value = buffer[res];
2: 18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0x0 ll
4: 0f 01 00 00 00 00 00 00 r1 += r0
5: 91 14 00 00 00 00 00 00 r4 = *(s8 *)(r1 + 0x0)
```
Without this patch, the verifier fails with "math between map_value
pointer and register with unbounded min value is not allowed" because
it cannot deduce that `r0` is within [0, 5].
According to the BPF instruction set[1], the instruction's offset field
(`insn->off`) is used to distinguish between signed (`off == 1`) and
unsigned division (`off == 0`). Moreover, we also follow the BPF division
and modulo runtime behavior (semantics) to handle special cases, such as
division by zero and signed division overflow.
- UDIV: dst = (src != 0) ? (dst / src) : 0
- SDIV: dst = (src == 0) ? 0 : ((src == -1 && dst == LLONG_MIN) ? LLONG_MIN : (dst / src))
- UMOD: dst = (src != 0) ? (dst % src) : dst
- SMOD: dst = (src == 0) ? dst : ((src == -1 && dst == LLONG_MIN) ? 0: (dst s% src))
Here is the overview of the changes made in this patch (See the code comments
for more details and examples):
1. For BPF_DIV: Firstly check whether the divisor is zero. If so, set the
destination register to zero (matching runtime behavior).
For non-zero constant divisors: goto `scalar(32)?_min_max_(u|s)div` functions.
- General cases: compute the new range by dividing max_dividend and
min_dividend by the constant divisor.
- Overflow case (SIGNED_MIN / -1) in signed division: mark the result
as unbounded if the dividend is not a single number.
2. For BPF_MOD: Firstly check whether the divisor is zero. If so, leave the
destination register unchanged (matching runtime behavior).
For non-zero constant divisors: goto `scalar(32)?_min_max_(u|s)mod` functions.
- General case: For signed modulo, the result's sign matches the
dividend's sign. And the result's absolute value is strictly bounded
by `min(abs(dividend), abs(divisor) - 1)`.
- Special care is taken when the divisor is SIGNED_MIN. By casting
to unsigned before negation and subtracting 1, we avoid signed
overflow and correctly calculate the maximum possible magnitude
(`res_max_abs` in the code).
- "Small dividend" case: If the dividend is already within the possible
result range (e.g., [-2, 5] % 10), the operation is an identity
function, and the destination register remains unchanged.
3. In `scalar(32)?_min_max_(u|s)(div|mod)` functions: After updating current
range, reset other ranges and tnum to unbounded/unknown.
e.g., in `scalar_min_max_sdiv`, signed 64-bit range is updated. Then reset
unsigned 64-bit range and 32-bit range to unbounded, and tnum to unknown.
Exception: in BPF_MOD's "small dividend" case, since the result remains
unchanged, we do not reset other ranges/tnum.
4. Also updated existing selftests based on the expected BPF_DIV and
BPF_MOD behavior.
[1] https://www.kernel.org/doc/Documentation/bpf/standardization/instruction-set.rst
Co-developed-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Co-developed-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Yazhou Tang <tangyazhou518@outlook.com>
Tested-by: syzbot@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20260119085458.182221-2-tangyazhou@zju.edu.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Ihor Solodrai says:
====================
bpf: Kernel functions with KF_IMPLICIT_ARGS
This series implements a generic "implicit arguments" feature for BPF
kernel functions. For context see prior work [1][2].
A mechanism is created for kfuncs to have arguments that are not
visible to the BPF programs, and are provided to the kernel function
implementation by the verifier.
This mechanism is then used in the kfuncs that have a parameter with
__prog annotation [3], which is the current way of passing struct
bpf_prog_aux pointer to kfuncs.
The function with implicit arguments is defined by KF_IMPLICIT_ARGS
flag in BTF_IDS_FLAGS set. In this series, only a pointer to struct
bpf_prog_aux can be implicit, although it is simple to extend this to
more types.
The verifier handles a kfunc with KF_IMPLICIT_ARGS by resolving it to
a different (actual) BTF prototype early in verification (patch #3).
A <kfunc>_impl function generated in BTF for a kfunc with implicit
args does not have a "bpf_kfunc" decl tag, and a kernel address. The
verifier will reject a program trying to call such an _impl kfunc.
The usage of <kfunc>_impl functions in BPF is only allowed for kfuncs
with an explicit kernel (or kmodule) declaration, that is in "legacy"
cases. As of this series, there are no legacy kernel functions, as all
__prog users are migrated to KF_IMPLICIT_ARGS. However the
implementation allows for legacy cases support in principle.
The series removes the following BPF kernel functions:
- bpf_stream_vprintk_impl
- bpf_task_work_schedule_resume_impl
- bpf_task_work_schedule_signal_impl
- bpf_wq_set_callback_impl
This will break existing BPF programs calling these functions (the
verifier will not load them) on new kernels.
To mitigate, BPF users are advised to use the following pattern [4]:
if (xxx_impl)
xxx_impl(..., NULL);
else
xxx(...);
Which can be wrapped in a macro.
The series consists of the following patches:
- patches #1 and #2 are non-functional refactoring in kernel/bpf
- patch #3 defines KF_IMPLICIT_ARGS flag and teaches the verifier
about it
- patches #4-#5 implement btf2btf transformation in resolve_btfids
- patch #6 adds selftests specific to KF_IMPLICIT_ARGS feature
- patches #7-#11 migrate the current users of __prog argument to
KF_IMPLICIT_ARGS
- patch #12 removes __prog arg suffix support from the kernel
- patch #13 updates the docs
[1] https://lore.kernel.org/bpf/20251029190113.3323406-1-ihor.solodrai@linux.dev/
[2] https://lore.kernel.org/bpf/20250924211716.1287715-1-ihor.solodrai@linux.dev/
[3] https://docs.kernel.org/bpf/kfuncs.html#prog-annotation
[4] https://lore.kernel.org/bpf/CAEf4BzbgPfRm9BX=TsZm-TsHFAHcwhPY4vTt=9OT-uhWqf8tqw@mail.gmail.com/
---
v2->v3:
- resolve_btfids: Use dynamic reallocation for btf2btf_context arrays (Andrii)
- resolve_btfids: Add missing free() for btf2btf_context arrays (AI)
- Other nits in resolve_btfids (Andrii, Eduard)
v2: https://lore.kernel.org/bpf/20260116201700.864797-1-ihor.solodrai@linux.dev/
v1->v2:
- Replace the following kernel functions with KF_IMPLICIT_ARGS version:
- bpf_stream_vprintk_impl -> bpf_stream_vprintk
- bpf_task_work_schedule_resume_impl -> bpf_task_work_schedule_resume
- bpf_task_work_schedule_signal_impl -> bpf_task_work_schedule_signal
- bpf_wq_set_callback_impl -> bpf_wq_set_callback_impl
- Remove __prog arg suffix support from the verifier
- Rework btf2btf implementation in resolve_btfids
- Do distill base and sort before BTF_ids patching
- Collect kfuncs based on BTF decl tags, before BTF_ids are patched
- resolve_btfids: use dynamic memory for intermediate data (Andrii)
- verifier: reset .subreg_def for caller saved registers on kfunc
call (Eduard)
- selftests/hid: remove Makefile changes (Benjamin)
- selftests/bpf: Add a patch (#11) migrating struct_ops_assoc test
to KF_IMPLICIT_ARGS
- Various nits across the series (Alexei, Andrii, Eduard)
v1: https://lore.kernel.org/bpf/20260109184852.1089786-1-ihor.solodrai@linux.dev/
---
====================
Link: https://patch.msgid.link/20260120222638.3976562-1-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A test kfunc named bpf_kfunc_multi_st_ops_test_1_impl() is a user of
__prog suffix. Subsequent patch removes __prog support in favor of
KF_IMPLICIT_ARGS, so migrate this kfunc to use implicit argument.
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-12-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Implement bpf_stream_vprintk with an implicit bpf_prog_aux argument,
and remote bpf_stream_vprintk_impl from the kernel.
Update the selftests to use the new API with implicit argument.
bpf_stream_vprintk macro is changed to use the new bpf_stream_vprintk
kfunc, and the extern definition of bpf_stream_vprintk_impl is
replaced accordingly.
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-11-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Implement bpf_task_work_schedule_* with an implicit bpf_prog_aux
argument, and remove corresponding _impl funcs from the kernel.
Update special kfunc checks in the verifier accordingly.
Update the selftests to use the new API with implicit argument.
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-10-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Remove extern declaration of bpf_wq_set_callback_impl() from
hid_bpf_helpers.h and replace bpf_wq_set_callback macro with a
corresponding new declaration.
Tested with:
# append tools/testing/selftests/hid/config and build the kernel
$ make -C tools/testing/selftests/hid
# in built kernel
$ ./tools/testing/selftests/hid/hid_bpf -t test_multiply_events_wq
TAP version 13
1..1
# Starting 1 tests from 1 test cases.
# RUN hid_bpf.test_multiply_events_wq ...
[ 2.575520] hid-generic 0003:0001:0A36.0001: hidraw0: USB HID v0.00 Device [test-uhid-device-138] on 138
# OK hid_bpf.test_multiply_events_wq
ok 1 hid_bpf.test_multiply_events_wq
# PASSED: 1 / 1 tests passed.
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
PASS
Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-9-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Implement bpf_wq_set_callback() with an implicit bpf_prog_aux
argument, and remove bpf_wq_set_callback_impl().
Update special kfunc checks in the verifier accordingly.
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-8-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add trivial end-to-end tests to validate that KF_IMPLICIT_ARGS flag is
properly handled by both resolve_btfids and the verifier.
Declare kfuncs in bpf_testmod. Check that bpf_prog_aux pointer is set
in the kfunc implementation. Verify that calls with implicit args and
a legacy case all work.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-7-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Implement BTF modifications in resolve_btfids to support BPF kernel
functions with implicit arguments.
For a kfunc marked with KF_IMPLICIT_ARGS flag, a new function
prototype is added to BTF that does not have implicit arguments. The
kfunc's prototype is then updated to a new one in BTF. This prototype
is the intended interface for the BPF programs.
A <func_name>_impl function is added to BTF to make the original kfunc
prototype searchable for the BPF verifier. If a <func_name>_impl
function already exists in BTF, its interpreted as a legacy case, and
this step is skipped.
Whether an argument is implicit is determined by its type:
currently only `struct bpf_prog_aux *` is supported.
As a result, the BTF associated with kfunc is changed from
__bpf_kfunc bpf_foo(int arg1, struct bpf_prog_aux *aux);
into
bpf_foo_impl(int arg1, struct bpf_prog_aux *aux);
__bpf_kfunc bpf_foo(int arg1);
For more context see previous discussions and patches [1][2].
[1] https://lore.kernel.org/dwarves/ba1650aa-fafd-49a8-bea4-bdddee7c38c9@linux.dev/
[2] https://lore.kernel.org/bpf/20251029190113.3323406-1-ihor.solodrai@linux.dev/
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-6-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Since recently [1][2] resolve_btfids executes final adjustments to the
kernel/module BTF before it's embedded into the target binary.
To keep the implementation simple, a clear and stable "pipeline" of
how BTF data flows through resolve_btfids would be helpful. Some BTF
modifications may change the ids of the types, so it is important to
maintain correct order of operations with respect to .BTF_ids
resolution too.
This patch refactors the BTF handling to establish the following
sequence:
- load target ELF sections
- load .BTF_ids symbols
- this will be a dependency of btf2btf transformations in
subsequent patches
- load BTF and its base as is
- (*) btf2btf transformations will happen here
- finalize_btf(), introduced in this patch
- does distill base and sort BTF
- resolve and patch .BTF_ids
This approach helps to avoid fixups in .BTF_ids data in case the ids
change at any point of BTF processing, because symbol resolution
happens on the finalized, ready to dump, BTF data.
This also gives flexibility in BTF transformations, because they will
happen on BTF that is not distilled and/or sorted yet, allowing to
freely add, remove and modify BTF types.
[1] https://lore.kernel.org/bpf/20251219181321.1283664-1-ihor.solodrai@linux.dev/
[2] https://lore.kernel.org/bpf/20260109130003.3313716-1-dolinux.peng@gmail.com/
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-5-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A kernel function bpf_foo marked with KF_IMPLICIT_ARGS flag is
expected to have two associated types in BTF:
* `bpf_foo` with a function prototype that omits implicit arguments
* `bpf_foo_impl` with a function prototype that matches the kernel
declaration of `bpf_foo`, but doesn't have a ksym associated with
its name
In order to support kfuncs with implicit arguments, the verifier has
to know how to resolve a call of `bpf_foo` to the correct BTF function
prototype and address.
To implement this, in add_kfunc_call() kfunc flags are checked for
KF_IMPLICIT_ARGS. For such kfuncs a BTF func prototype is adjusted to
the one found for `bpf_foo_impl` (func_name + "_impl" suffix, by
convention) function in BTF.
This effectively changes the signature of the `bpf_foo` kfunc in the
context of verification: from one without implicit args to the one
with full argument list.
The values of implicit arguments by design are provided by the
verifier, and so they can only be of particular types. In this patch
the only allowed implicit arg type is a pointer to struct
bpf_prog_aux.
In order for the verifier to correctly set an implicit bpf_prog_aux
arg value at runtime, is_kfunc_arg_prog() is extended to check for the
arg type. At a point when prog arg is determined in check_kfunc_args()
the kfunc with implicit args already has a prototype with full
argument list, so the existing value patch mechanism just works.
If a new kfunc with KF_IMPLICIT_ARG is declared for an existing kfunc
that uses a __prog argument (a legacy case), the prototype
substitution works in exactly the same way, assuming the kfunc follows
the _impl naming convention. The difference is only in how _impl
prototype is added to the BTF, which is not the verifier's
concern. See a subsequent resolve_btfids patch for details.
__prog suffix is still supported at this point, but will be removed in
a subsequent patch, after current users are moved to KF_IMPLICIT_ARGS.
Introduction of KF_IMPLICIT_ARGS revealed an issue with zero-extension
tracking, because an explicit rX = 0 in place of the verifier-supplied
argument is now absent if the arg is implicit (the BPF prog doesn't
pass a dummy NULL anymore). To mitigate this, reset the subreg_def of
all caller saved registers in check_kfunc_call() [1].
[1] https://lore.kernel.org/bpf/b4a760ef828d40dac7ea6074d39452bb0dc82caa.camel@gmail.com/
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-4-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
There is code duplication between add_kfunc_call() and
fetch_kfunc_meta() collecting information about a kfunc from BTF.
Introduce struct bpf_kfunc_meta to hold common kfunc BTF data and
implement fetch_kfunc_meta() to fill it in, instead of struct
bpf_kfunc_call_arg_meta directly.
Then use these in add_kfunc_call() and (new) fetch_kfunc_arg_meta()
functions, and fixup previous usages of fetch_kfunc_meta() to
fetch_kfunc_arg_meta().
Besides the code dedup, this change enables add_kfunc_call() to access
kfunc->flags.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-3-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
btf_kfunc_id_set_contains() is called by fetch_kfunc_meta() in the BPF
verifier to get the kfunc flags stored in the .BTF_ids ELF section.
If it returns NULL instead of a valid pointer, it's interpreted as an
illegal kfunc usage failing the verification.
There are two potential reasons for btf_kfunc_id_set_contains() to
return NULL:
1. Provided kfunc BTF id is not present in relevant kfunc id sets.
2. The kfunc is not allowed, as determined by the program type
specific filter [1].
The filter functions accept a pointer to `struct bpf_prog`, so they
might implicitly depend on earlier stages of verification, when
bpf_prog members are set.
For example, bpf_qdisc_kfunc_filter() in linux/net/sched/bpf_qdisc.c
inspects prog->aux->st_ops [2], which is initialized in:
check_attach_btf_id() -> check_struct_ops_btf_id()
So far this hasn't been an issue, because fetch_kfunc_meta() is the
only caller of btf_kfunc_id_set_contains().
However in subsequent patches of this series it is necessary to
inspect kfunc flags earlier in BPF verifier, in the add_kfunc_call().
To resolve this, refactor btf_kfunc_id_set_contains() into two
interface functions:
* btf_kfunc_flags() that simply returns pointer to kfunc_flags
without applying the filters
* btf_kfunc_is_allowed() that both checks for kfunc_flags existence
(which is a requirement for a kfunc to be allowed) and applies the
prog filters
See [3] for the previous version of this patch.
[1] https://lore.kernel.org/all/20230519225157.760788-7-aditi.ghag@isovalent.com/
[2] https://lore.kernel.org/all/20250409214606.2000194-4-ameryhung@gmail.com/
[3] https://lore.kernel.org/bpf/20251029190113.3323406-3-ihor.solodrai@linux.dev/
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-2-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
An (admittedly problematic) optimization change in LLVM 20 [1] turns
known division by zero into the equivalent of __builtin_unreachable(),
which invokes undefined behavior if it is encountered in a control flow
graph, destroying code generation. When compile testing for x86_64,
objtool flags an instance of this optimization triggering in
msm_dp_ctrl_config_msa(), inlined into msm_dp_ctrl_on_stream():
drivers/gpu/drm/msm/msm.o: warning: objtool: msm_dp_ctrl_on_stream(): unexpected end of section .text.msm_dp_ctrl_on_stream
The zero division happens if the else branch in the first if statement
in msm_dp_ctrl_config_msa() is taken because pixel_div is initialized to
zero and it is not possible for LLVM to eliminate the else branch since
rate is still not known after inlining into msm_dp_ctrl_on_stream().
Transform the if statements into a switch statement with a default case
with the existing error print and an early return to avoid the invalid
division. Add a comment to note this helps the compiler, even though the
case is known to be unreachable. With this, pixel_dev's default zero
initialization can be dropped, as it is dead with this change.
Fixes: c943b4948b ("drm/msm/dp: add displayPort driver support")
Link: 37932643ab [1]
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202601081959.9UVJEOfP-lkp@intel.com/
Suggested-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/698355/
Link: https://lore.kernel.org/r/20260113-drm-msm-dp_ctrl-avoid-zero-div-v2-1-f1aa67bf6e8e@kernel.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Some of error messages in RM reference block index, while other print
the enum value (which is shifted by 1), not to mention that some of the
messages are misleading. Reformat the messages, making them more clear
and also always printing the hardware block name.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/698774/
Link: https://lore.kernel.org/r/20260115-dpu-fix-dspp-v1-1-b73152c147b3@oss.qualcomm.com
Add support for Display Processing Unit (DPU) version 13.0
on the Kaanapali platform. This version introduces changes
to the SSPP sub-block structure. Add common block and rectangle
blocks to accommodate these structural modifications for
compatibility.
Co-developed-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Yuanjie Yang <yuanjie.yang@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/698716/
Link: https://lore.kernel.org/r/20260115092749.533-13-yuanjie.yang@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Add support for Kaanapali platform SSPP sub-blocks, which
introduce structural changes including register additions,
removals, and relocations. Add the new common and rectangle
blocks, and update register definitions and handling to
ensure compatibility with DPU v13.0.
Co-developed-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Signed-off-by: Yuanjie Yang <yuanjie.yang@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/698712/
Link: https://lore.kernel.org/r/20260115092749.533-11-yuanjie.yang@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
NFC stack in Linux is in poor shape, with several bugs being discovered
last years via fuzzing, not much new development happening and limited
review and testing. It requires some more effort than drive-by reviews
I have been offering last one or two years.
I don't have much time nor business interests to keep looking at NFC,
so let's drop me from the maintainers to clearly indicate that more
hands are needed.
Acked-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260118094822.10126-2-krzysztof.kozlowski@oss.qualcomm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
DPU version 13.0.0 introduces changes to the interrupt register
layout. Update the driver to support these modifications for
proper interrupt handling.
Co-developed-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Yuanjie Yang <yuanjie.yang@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/698708/
Link: https://lore.kernel.org/r/20260115092749.533-9-yuanjie.yang@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Add DSI PHY support for the Kaanapali platform, Kaanapali introduce
addition of DSI2/DSI2_phy compared to SM8650. However, based on the
HPG diagram, only DSI0_phy and DSI1_phy works.
Co-developed-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Yuanjie Yang <yuanjie.yang@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/698705/
Link: https://lore.kernel.org/r/20260115092749.533-7-yuanjie.yang@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Add DPU version 13.0 for Qualcomm Kaanapali Soc. The Kaanapali
DPU and SM8750 have significant differences, including additions
and removals of registers, as well as changes in register addresses.
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Yuanjie Yang <yuanjie.yang@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/698694/
Link: https://lore.kernel.org/r/20260115092749.533-2-yuanjie.yang@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Code in dpu_hw_sspp_setup_format() doesn't handle UBWC versions bigger
than 4.0. Replace switch-case with if-else checks, making sure that the
register is initialized on UBWC 5.x (and later) hosts.
Fixes: c2577fc174 ("drm/msm/dpu: Add support for SM8750")
Tested-by: Val Packett <val@packett.cool> # x1e80100-dell-latitude-7455
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/699280/
Link: https://lore.kernel.org/r/20260119-msm-ubwc-fixes-v4-4-0987acc0427f@oss.qualcomm.com
Since DPU 8.0 there is a separate register for the second rectangle,
which needs to be programmed with the UBWC config if multirect is being
used. Write pipe's UBWC configuration to the correct register.
Fixes: 100d7ef699 ("drm/msm/dpu: add support for SM8450")
Tested-by: Val Packett <val@packett.cool> # x1e80100-dell-latitude-7455
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/699277/
Link: https://lore.kernel.org/r/20260119-msm-ubwc-fixes-v4-3-0987acc0427f@oss.qualcomm.com
As in all other places, the Highest Bank Bit value should be programmed
into the hardware with the offset of -13. Correct the value written
into the register to prevent unpredictable results.
Fixes: 227d4ce0b0 ("drm/msm: Offset MDSS HBB value by 13")
Tested-by: Val Packett <val@packett.cool> # x1e80100-dell-latitude-7455
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/699276/
Link: https://lore.kernel.org/r/20260119-msm-ubwc-fixes-v4-2-0987acc0427f@oss.qualcomm.com
As in the previous generations, on UBWC 5.x and 6.x devices the Highest
Bank Bit value should be programmed into the hardware with the offset of
-13. Correct the value written into the register to prevent
unpredictable results.
Fixes: 227d4ce0b0 ("drm/msm: Offset MDSS HBB value by 13")
Tested-by: Val Packett <val@packett.cool> # x1e80100-dell-latitude-7455
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/699274/
Link: https://lore.kernel.org/r/20260119-msm-ubwc-fixes-v4-1-0987acc0427f@oss.qualcomm.com
The strchr() function these days return const/non-const based on the arg
it receives, and sometimes we need to use casts when we're dealing with
variables that are used in code that needs to safely change the returned
value and sometimes not (as it points to really const areas).
Tweak one such case.
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
As it is just used to waste some cycles, not being used as all, to
silence some compilers.
Noticed with gcc version 16.0.1 20260115 on fedora 44:
tests/sw-clock.c: In function '__test__sw_clock_freq':
tests/sw-clock.c:31:22: error: variable 'tmp' set but not used [-Werror=unused-but-set-variable=]
31 | volatile int tmp = 0;
| ^~~
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The parsing of jobserver options is done in a massive try: block that hides
problems and (perhaps) bugs. Split up that block and make the logic
explicit by moving the initial parsing of MAKEFLAGS out of that block. Add
warnings in the places things can go wrong.
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
- Fix a refcount leak in of_alias_scan()
- Support decending into child nodes when populating nodes in /firmware
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Merge tag 'devicetree-fixes-for-6.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
Pull devicetree fixes from Rob Herring:
- Fix a refcount leak in of_alias_scan()
- Support descending into child nodes when populating nodes
in /firmware
* tag 'devicetree-fixes-for-6.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
of: fix reference count leak in of_alias_scan()
of: platform: Use default match table for /firmware
Some folks evidently have muscle memory expecting kernel-doc to be under
scripts/. Now that we have moved it to tools/docs, leave behind a symbolic
link to reduce the global profanity count.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Now that the Sphinx build does not use the kerneldoc_bin configuration
variable, we shouldn't try to set it in the build wrapper or we get a nifty
warning:
WARNING: unknown config value 'kerneldoc_bin' in override, ignoring
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
In the past, this contained the location of the binary file to parse
kernel-doc. Nowadays, it is used only for debugging purposes, inside
kerneldoc.py extension.
Move it to sphinx/kerneldoc.py, to avoid needing to handle with it
on several places.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <c0fa9f561c1dd4370f9096de4195a9214763c51c.1768823489.git.mchehab+huawei@kernel.org>
The description there is quite vague. Make it clearer.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <94269990e2d665bec08a1b6f4d28d84939cb9d83.1768823489.git.mchehab+huawei@kernel.org>
It makes sense to describe what kernel-doc is expected to return
on its help message. Move such messages to argparse epilog.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <3bcfa48016770929fcd073376515e3ff0b777ea8.1768823489.git.mchehab+huawei@kernel.org>
kernel-doc is the last documentation-related tool still living outside of
the tools/docs directory; the time has come to move it over.
[mchehab: fixed kdoc lib location]
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <311d17e403524349940a8b12de6b5e91e554b1f4.1768823489.git.mchehab+huawei@kernel.org>
The ability to build the docs with an external kernel-doc program involves
some truly confusing logic and complicates the task of moving kernel-doc
out of scripts/. But this feature is not useful for normal documentation
builds, and the external kernel-doc can always be run by hand when it needs
debugging. So just remove that feature and make life easier.
There is still a bunch of logic to build a command line that we never use;
the idea is to be able to output it, but I'm not sure if that is worth
keeping.
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <a97a8361546648906344457a7e92e4db533048a9.1768823489.git.mchehab+huawei@kernel.org>
