<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/arm64/net, branch master</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>bpf, arm64: Emit BTI for indirect jump target</title>
<updated>2026-04-16T14:03:41+00:00</updated>
<author>
<name>Xu Kuohai</name>
<email>xukuohai@huawei.com</email>
</author>
<published>2026-04-16T06:43:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f6606a44bc438ec5f1d450d0153878e80e79ff80'/>
<id>f6606a44bc438ec5f1d450d0153878e80e79ff80</id>
<content type='text'>
On CPUs that support BTI, the indirect jump selftest triggers a kernel
panic because there is no BTI instructions at the indirect jump targets.

Fix it by emitting a BTI instruction for each indirect jump target.

For reference, below is a sample panic log.

Internal error: Oops - BTI: 0000000036000003 [#1]  SMP
...
Call trace:
 bpf_prog_2e5f1c71c13ac3e0_big_jump_table+0x54/0xf8 (P)
 bpf_prog_run_pin_on_cpu+0x140/0x468
 bpf_prog_test_run_syscall+0x280/0x3b8
 bpf_prog_test_run+0x22c/0x2c0

Fixes: f4a66cf1cb14 ("bpf: arm64: Add support for indirect jumps")
Reviewed-by: Anton Protopopov &lt;a.s.protopopov@gmail.com&gt; # v8
Reviewed-by: Emil Tsalapatis &lt;emil@etsalapatis.com&gt; # v12
Acked-by: Leon Hwang &lt;leon.hwang@linux.dev&gt;
Signed-off-by: Xu Kuohai &lt;xukuohai@huawei.com&gt;
Link: https://lore.kernel.org/r/20260416064341.151802-6-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On CPUs that support BTI, the indirect jump selftest triggers a kernel
panic because there is no BTI instructions at the indirect jump targets.

Fix it by emitting a BTI instruction for each indirect jump target.

For reference, below is a sample panic log.

Internal error: Oops - BTI: 0000000036000003 [#1]  SMP
...
Call trace:
 bpf_prog_2e5f1c71c13ac3e0_big_jump_table+0x54/0xf8 (P)
 bpf_prog_run_pin_on_cpu+0x140/0x468
 bpf_prog_test_run_syscall+0x280/0x3b8
 bpf_prog_test_run+0x22c/0x2c0

Fixes: f4a66cf1cb14 ("bpf: arm64: Add support for indirect jumps")
Reviewed-by: Anton Protopopov &lt;a.s.protopopov@gmail.com&gt; # v8
Reviewed-by: Emil Tsalapatis &lt;emil@etsalapatis.com&gt; # v12
Acked-by: Leon Hwang &lt;leon.hwang@linux.dev&gt;
Signed-off-by: Xu Kuohai &lt;xukuohai@huawei.com&gt;
Link: https://lore.kernel.org/r/20260416064341.151802-6-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: Pass bpf_verifier_env to JIT</title>
<updated>2026-04-16T14:03:40+00:00</updated>
<author>
<name>Xu Kuohai</name>
<email>xukuohai@huawei.com</email>
</author>
<published>2026-04-16T06:43:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d9ef13f72711f2dad64cd4445472ded98fb6c954'/>
<id>d9ef13f72711f2dad64cd4445472ded98fb6c954</id>
<content type='text'>
Pass bpf_verifier_env to bpf_int_jit_compile(). The follow-up patch will
use env-&gt;insn_aux_data in the JIT stage to detect indirect jump targets.

Since bpf_prog_select_runtime() can be called by cbpf and lib/test_bpf.c
code without verifier, introduce helper __bpf_prog_select_runtime()
to accept the env parameter.

Remove the call to bpf_prog_select_runtime() in bpf_prog_load(), and
switch to call __bpf_prog_select_runtime() in the verifier, with env
variable passed. The original bpf_prog_select_runtime() is preserved for
cbpf and lib/test_bpf.c, where env is NULL.

Now all constants blinding calls are moved into the verifier, except
the cbpf and lib/test_bpf.c cases. The instructions arrays are adjusted
by bpf_patch_insn_data() function for normal cases, so there is no need
to call adjust_insn_arrays() in bpf_jit_blind_constants(). Remove it.

Reviewed-by: Anton Protopopov &lt;a.s.protopopov@gmail.com&gt; # v8
Reviewed-by: Emil Tsalapatis &lt;emil@etsalapatis.com&gt; # v12
Acked-by: Hengqi Chen &lt;hengqi.chen@gmail.com&gt; # v14
Signed-off-by: Xu Kuohai &lt;xukuohai@huawei.com&gt;
Link: https://lore.kernel.org/r/20260416064341.151802-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pass bpf_verifier_env to bpf_int_jit_compile(). The follow-up patch will
use env-&gt;insn_aux_data in the JIT stage to detect indirect jump targets.

Since bpf_prog_select_runtime() can be called by cbpf and lib/test_bpf.c
code without verifier, introduce helper __bpf_prog_select_runtime()
to accept the env parameter.

Remove the call to bpf_prog_select_runtime() in bpf_prog_load(), and
switch to call __bpf_prog_select_runtime() in the verifier, with env
variable passed. The original bpf_prog_select_runtime() is preserved for
cbpf and lib/test_bpf.c, where env is NULL.

Now all constants blinding calls are moved into the verifier, except
the cbpf and lib/test_bpf.c cases. The instructions arrays are adjusted
by bpf_patch_insn_data() function for normal cases, so there is no need
to call adjust_insn_arrays() in bpf_jit_blind_constants(). Remove it.

Reviewed-by: Anton Protopopov &lt;a.s.protopopov@gmail.com&gt; # v8
Reviewed-by: Emil Tsalapatis &lt;emil@etsalapatis.com&gt; # v12
Acked-by: Hengqi Chen &lt;hengqi.chen@gmail.com&gt; # v14
Signed-off-by: Xu Kuohai &lt;xukuohai@huawei.com&gt;
Link: https://lore.kernel.org/r/20260416064341.151802-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: Move constants blinding out of arch-specific JITs</title>
<updated>2026-04-16T14:03:40+00:00</updated>
<author>
<name>Xu Kuohai</name>
<email>xukuohai@huawei.com</email>
</author>
<published>2026-04-16T06:43:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d3e945223e0158c85dbde23de4f89493a2a817f6'/>
<id>d3e945223e0158c85dbde23de4f89493a2a817f6</id>
<content type='text'>
During the JIT stage, constants blinding rewrites instructions but only
rewrites the private instruction copy of the JITed subprog, leaving the
global env-&gt;prog-&gt;insnsi and env-&gt;insn_aux_data untouched. This causes a
mismatch between subprog instructions and the global state, making it
difficult to use the global data in the JIT.

To avoid this mismatch, and given that all arch-specific JITs already
support constants blinding, move it to the generic verifier code, and
switch to rewrite the global env-&gt;prog-&gt;insnsi with the global states
adjusted, as other rewrites in the verifier do.

This removes the constants blinding calls in each JIT, which are largely
duplicated code across architectures.

Since constants blinding is only required for JIT, and there are two
JIT entry functions, jit_subprogs() for BPF programs with multiple
subprogs and bpf_prog_select_runtime() for programs with no subprogs,
move the constants blinding invocation into these two functions.

In the verifier path, bpf_patch_insn_data() is used to keep global
verifier auxiliary data in sync with patched instructions. A key
question is whether this global auxiliary data should be restored
on the failure path.

Besides instructions, bpf_patch_insn_data() adjusts:
  - prog-&gt;aux-&gt;poke_tab
  - env-&gt;insn_array_maps
  - env-&gt;subprog_info
  - env-&gt;insn_aux_data

For prog-&gt;aux-&gt;poke_tab, it is only used by JIT or only meaningful after
JIT succeeds, so it does not need to be restored on the failure path.

For env-&gt;insn_array_maps, when JIT fails, programs using insn arrays
are rejected by bpf_insn_array_ready() due to missing JIT addresses.
Hence, env-&gt;insn_array_maps is only meaningful for JIT and does not need
to be restored.

For subprog_info, if jit_subprogs fails and CONFIG_BPF_JIT_ALWAYS_ON
is not enabled, kernel falls back to interpreter. In this case,
env-&gt;subprog_info is used to determine subprogram stack depth. So it
must be restored on failure.

For env-&gt;insn_aux_data, it is freed by clear_insn_aux_data() at the
end of bpf_check(). Before freeing, clear_insn_aux_data() loops over
env-&gt;insn_aux_data to release jump targets recorded in it. The loop
uses env-&gt;prog-&gt;len as the array length, but this length no longer
matches the actual size of the adjusted env-&gt;insn_aux_data array after
constants blinding.

To address it, a simple approach is to keep insn_aux_data as adjusted
after failure, since it will be freed shortly, and record its actual size
for the loop in clear_insn_aux_data(). But since clear_insn_aux_data()
uses the same index to loop over both env-&gt;prog-&gt;insnsi and env-&gt;insn_aux_data,
this approach results in incorrect index for the insnsi array. So an
alternative approach is adopted: clone the original env-&gt;insn_aux_data
before blinding and restore it after failure, similar to env-&gt;prog.

For classic BPF programs, constants blinding works as before since it
is still invoked from bpf_prog_select_runtime().

Reviewed-by: Anton Protopopov &lt;a.s.protopopov@gmail.com&gt; # v8
Reviewed-by: Hari Bathini &lt;hbathini@linux.ibm.com&gt; # powerpc jit
Reviewed-by: Pu Lehui &lt;pulehui@huawei.com&gt; # riscv jit
Acked-by: Hengqi Chen &lt;hengqi.chen@gmail.com&gt; # loongarch jit
Signed-off-by: Xu Kuohai &lt;xukuohai@huawei.com&gt;
Link: https://lore.kernel.org/r/20260416064341.151802-2-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
During the JIT stage, constants blinding rewrites instructions but only
rewrites the private instruction copy of the JITed subprog, leaving the
global env-&gt;prog-&gt;insnsi and env-&gt;insn_aux_data untouched. This causes a
mismatch between subprog instructions and the global state, making it
difficult to use the global data in the JIT.

To avoid this mismatch, and given that all arch-specific JITs already
support constants blinding, move it to the generic verifier code, and
switch to rewrite the global env-&gt;prog-&gt;insnsi with the global states
adjusted, as other rewrites in the verifier do.

This removes the constants blinding calls in each JIT, which are largely
duplicated code across architectures.

Since constants blinding is only required for JIT, and there are two
JIT entry functions, jit_subprogs() for BPF programs with multiple
subprogs and bpf_prog_select_runtime() for programs with no subprogs,
move the constants blinding invocation into these two functions.

In the verifier path, bpf_patch_insn_data() is used to keep global
verifier auxiliary data in sync with patched instructions. A key
question is whether this global auxiliary data should be restored
on the failure path.

Besides instructions, bpf_patch_insn_data() adjusts:
  - prog-&gt;aux-&gt;poke_tab
  - env-&gt;insn_array_maps
  - env-&gt;subprog_info
  - env-&gt;insn_aux_data

For prog-&gt;aux-&gt;poke_tab, it is only used by JIT or only meaningful after
JIT succeeds, so it does not need to be restored on the failure path.

For env-&gt;insn_array_maps, when JIT fails, programs using insn arrays
are rejected by bpf_insn_array_ready() due to missing JIT addresses.
Hence, env-&gt;insn_array_maps is only meaningful for JIT and does not need
to be restored.

For subprog_info, if jit_subprogs fails and CONFIG_BPF_JIT_ALWAYS_ON
is not enabled, kernel falls back to interpreter. In this case,
env-&gt;subprog_info is used to determine subprogram stack depth. So it
must be restored on failure.

For env-&gt;insn_aux_data, it is freed by clear_insn_aux_data() at the
end of bpf_check(). Before freeing, clear_insn_aux_data() loops over
env-&gt;insn_aux_data to release jump targets recorded in it. The loop
uses env-&gt;prog-&gt;len as the array length, but this length no longer
matches the actual size of the adjusted env-&gt;insn_aux_data array after
constants blinding.

To address it, a simple approach is to keep insn_aux_data as adjusted
after failure, since it will be freed shortly, and record its actual size
for the loop in clear_insn_aux_data(). But since clear_insn_aux_data()
uses the same index to loop over both env-&gt;prog-&gt;insnsi and env-&gt;insn_aux_data,
this approach results in incorrect index for the insnsi array. So an
alternative approach is adopted: clone the original env-&gt;insn_aux_data
before blinding and restore it after failure, similar to env-&gt;prog.

For classic BPF programs, constants blinding works as before since it
is still invoked from bpf_prog_select_runtime().

Reviewed-by: Anton Protopopov &lt;a.s.protopopov@gmail.com&gt; # v8
Reviewed-by: Hari Bathini &lt;hbathini@linux.ibm.com&gt; # powerpc jit
Reviewed-by: Pu Lehui &lt;pulehui@huawei.com&gt; # riscv jit
Acked-by: Hengqi Chen &lt;hengqi.chen@gmail.com&gt; # loongarch jit
Signed-off-by: Xu Kuohai &lt;xukuohai@huawei.com&gt;
Link: https://lore.kernel.org/r/20260416064341.151802-2-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>bpf, arm64: Remove redundant bpf_flush_icache() after pack allocator finalize</title>
<updated>2026-04-15T19:09:46+00:00</updated>
<author>
<name>Puranjay Mohan</name>
<email>puranjay@kernel.org</email>
</author>
<published>2026-04-13T19:11:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=42f18ae53011826cfd3c84d041817e7f07bc645b'/>
<id>42f18ae53011826cfd3c84d041817e7f07bc645b</id>
<content type='text'>
bpf_flush_icache() calls flush_icache_range() to clean the data cache
and invalidate the instruction cache for the JITed code region. However,
since commit 1dad391daef1 ("bpf, arm64: use bpf_prog_pack for memory
management"), this flush is redundant.

bpf_jit_binary_pack_finalize() copies the JITed instructions to the ROX
region via bpf_arch_text_copy() -&gt; aarch64_insn_copy() -&gt; __text_poke(),
and __text_poke() already calls flush_icache_range() on the written
range. The subsequent bpf_flush_icache() repeats the same cache
maintenance on an overlapping range, including an unnecessary second
synchronous IPI to all CPUs via kick_all_cpus_sync().

Remove the redundant bpf_flush_icache() call and its now-unused
definition.

Fixes: 1dad391daef1 ("bpf, arm64: use bpf_prog_pack for memory management")
Acked-by: Song Liu &lt;song@kernel.org&gt;
Signed-off-by: Puranjay Mohan &lt;puranjay@kernel.org&gt;
Acked-by: Breno Leitao &lt;leitao@debian.org&gt;
Link: https://lore.kernel.org/r/20260413191111.3426023-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
bpf_flush_icache() calls flush_icache_range() to clean the data cache
and invalidate the instruction cache for the JITed code region. However,
since commit 1dad391daef1 ("bpf, arm64: use bpf_prog_pack for memory
management"), this flush is redundant.

bpf_jit_binary_pack_finalize() copies the JITed instructions to the ROX
region via bpf_arch_text_copy() -&gt; aarch64_insn_copy() -&gt; __text_poke(),
and __text_poke() already calls flush_icache_range() on the written
range. The subsequent bpf_flush_icache() repeats the same cache
maintenance on an overlapping range, including an unnecessary second
synchronous IPI to all CPUs via kick_all_cpus_sync().

Remove the redundant bpf_flush_icache() call and its now-unused
definition.

Fixes: 1dad391daef1 ("bpf, arm64: use bpf_prog_pack for memory management")
Acked-by: Song Liu &lt;song@kernel.org&gt;
Signed-off-by: Puranjay Mohan &lt;puranjay@kernel.org&gt;
Acked-by: Breno Leitao &lt;leitao@debian.org&gt;
Link: https://lore.kernel.org/r/20260413191111.3426023-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>bpf, arm64: Fix off-by-one in check_imm signed range check</title>
<updated>2026-04-15T19:08:03+00:00</updated>
<author>
<name>Daniel Borkmann</name>
<email>daniel@iogearbox.net</email>
</author>
<published>2026-04-15T12:14:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1dd8be4ec722ce54e4cace59f3a4ba658111b3ec'/>
<id>1dd8be4ec722ce54e4cace59f3a4ba658111b3ec</id>
<content type='text'>
check_imm(bits, imm) is used in the arm64 BPF JIT to verify that
a branch displacement (in arm64 instruction units) fits into the
signed N-bit immediate field of a B, B.cond or CBZ/CBNZ encoding
before it is handed to the encoder. The macro currently tests for
(imm &gt; 0 &amp;&amp; imm &gt;&gt; bits) || (imm &lt; 0 &amp;&amp; ~imm &gt;&gt; bits) which admits
values in [-2^N, 2^N) — effectively a signed (N+1)-bit range. A
signed N-bit field only holds [-2^(N-1), 2^(N-1)), so the check
admits one extra bit of range on each side.

In particular, for check_imm19(), values in [2^18, 2^19) slip past
the check but do not fit into the 19-bit signed imm19 field of
B.cond. aarch64_insn_encode_immediate() then masks the raw value
into the 19-bit field, setting bit 18 (the sign bit) and flipping
a forward branch into a backward one. Same class of issue exists
for check_imm26() and the B/BL encoding. Shift by (bits - 1)
instead of bits so the actual signed N-bit range is enforced.

Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler")
Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Reviewed-by: Puranjay Mohan &lt;puranjay@kernel.org&gt;
Link: https://lore.kernel.org/r/20260415121403.639619-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
check_imm(bits, imm) is used in the arm64 BPF JIT to verify that
a branch displacement (in arm64 instruction units) fits into the
signed N-bit immediate field of a B, B.cond or CBZ/CBNZ encoding
before it is handed to the encoder. The macro currently tests for
(imm &gt; 0 &amp;&amp; imm &gt;&gt; bits) || (imm &lt; 0 &amp;&amp; ~imm &gt;&gt; bits) which admits
values in [-2^N, 2^N) — effectively a signed (N+1)-bit range. A
signed N-bit field only holds [-2^(N-1), 2^(N-1)), so the check
admits one extra bit of range on each side.

In particular, for check_imm19(), values in [2^18, 2^19) slip past
the check but do not fit into the 19-bit signed imm19 field of
B.cond. aarch64_insn_encode_immediate() then masks the raw value
into the 19-bit field, setting bit 18 (the sign bit) and flipping
a forward branch into a backward one. Same class of issue exists
for check_imm26() and the B/BL encoding. Shift by (bits - 1)
instead of bits so the actual signed N-bit range is enforced.

Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler")
Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Reviewed-by: Puranjay Mohan &lt;puranjay@kernel.org&gt;
Link: https://lore.kernel.org/r/20260415121403.639619-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>bpf, arm64: Use ORR-based MOV for general-purpose registers</title>
<updated>2026-03-03T16:43:10+00:00</updated>
<author>
<name>Puranjay Mohan</name>
<email>puranjay@kernel.org</email>
</author>
<published>2026-02-25T13:43:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b1d6bd5462f1e16adb805ce293bd11e9d7c47e6c'/>
<id>b1d6bd5462f1e16adb805ce293bd11e9d7c47e6c</id>
<content type='text'>
The A64_MOV macro unconditionally uses ADD Rd, Rn, #0 to implement
register moves. While functionally correct, this is not the canonical
encoding when both operands are general-purpose registers.

On AArch64, MOV has two aliases depending on the operand registers:
  - MOV &lt;Xd|SP&gt;, &lt;Xn|SP&gt;  →  ADD &lt;Xd|SP&gt;, &lt;Xn|SP&gt;, #0
  - MOV &lt;Xd&gt;, &lt;Xn&gt;        →  ORR &lt;Xd&gt;, XZR, &lt;Xn&gt;

The ADD form is required when the stack pointer is involved (as ORR
does not accept SP), while the ORR form is the preferred encoding for
general-purpose registers.

The ORR encoding is also measurably faster on modern microarchitectures.
A microbenchmark [1] comparing dependent chains of MOV (ORR) vs ADD #0
on an ARM Neoverse-V2 (72-core, 3.4 GHz) shows:

  === mov (ORR Xd, XZR, Xn) ===
  run1 cycles/op=0.749859456
  run2 cycles/op=0.749991250
  run3 cycles/op=0.749601847
  avg cycles/op=0.749817518

  === add0 (ADD Xd, Xn, #0) ===
  run1 cycles/op=1.004777689
  run2 cycles/op=1.004558266
  run3 cycles/op=1.004806559
  avg cycles/op=1.004714171

The ORR form completes in ~0.75 cycles/op vs ~1.00 cycles/op for ADD #0,
a ~25% improvement. This is likely because the CPU's register renaming
hardware can eliminate ORR-based moves, while ADD #0 must go through the
ALU pipeline.

Update A64_MOV to select the appropriate encoding at JIT time:
use ADD when either register is A64_SP, and ORR (via
aarch64_insn_gen_move_reg()) otherwise.

Update verifier_private_stack selftests to expect "mov x7, x0" instead
of "add x7, x0, #0x0" in the JITed instruction checks, matching the
new ORR-based encoding.

[1] https://github.com/puranjaymohan/scripts/blob/main/arm64/bench/run_mov_vs_add0.sh

Signed-off-by: Puranjay Mohan &lt;puranjay@kernel.org&gt;
Acked-by: Xu Kuohai &lt;xukuohai@huawei.com&gt;
Link: https://lore.kernel.org/r/20260225134339.2723288-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The A64_MOV macro unconditionally uses ADD Rd, Rn, #0 to implement
register moves. While functionally correct, this is not the canonical
encoding when both operands are general-purpose registers.

On AArch64, MOV has two aliases depending on the operand registers:
  - MOV &lt;Xd|SP&gt;, &lt;Xn|SP&gt;  →  ADD &lt;Xd|SP&gt;, &lt;Xn|SP&gt;, #0
  - MOV &lt;Xd&gt;, &lt;Xn&gt;        →  ORR &lt;Xd&gt;, XZR, &lt;Xn&gt;

The ADD form is required when the stack pointer is involved (as ORR
does not accept SP), while the ORR form is the preferred encoding for
general-purpose registers.

The ORR encoding is also measurably faster on modern microarchitectures.
A microbenchmark [1] comparing dependent chains of MOV (ORR) vs ADD #0
on an ARM Neoverse-V2 (72-core, 3.4 GHz) shows:

  === mov (ORR Xd, XZR, Xn) ===
  run1 cycles/op=0.749859456
  run2 cycles/op=0.749991250
  run3 cycles/op=0.749601847
  avg cycles/op=0.749817518

  === add0 (ADD Xd, Xn, #0) ===
  run1 cycles/op=1.004777689
  run2 cycles/op=1.004558266
  run3 cycles/op=1.004806559
  avg cycles/op=1.004714171

The ORR form completes in ~0.75 cycles/op vs ~1.00 cycles/op for ADD #0,
a ~25% improvement. This is likely because the CPU's register renaming
hardware can eliminate ORR-based moves, while ADD #0 must go through the
ALU pipeline.

Update A64_MOV to select the appropriate encoding at JIT time:
use ADD when either register is A64_SP, and ORR (via
aarch64_insn_gen_move_reg()) otherwise.

Update verifier_private_stack selftests to expect "mov x7, x0" instead
of "add x7, x0, #0x0" in the JITed instruction checks, matching the
new ORR-based encoding.

[1] https://github.com/puranjaymohan/scripts/blob/main/arm64/bench/run_mov_vs_add0.sh

Signed-off-by: Puranjay Mohan &lt;puranjay@kernel.org&gt;
Acked-by: Xu Kuohai &lt;xukuohai@huawei.com&gt;
Link: https://lore.kernel.org/r/20260225134339.2723288-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing</title>
<updated>2026-02-26T19:19:00+00:00</updated>
<author>
<name>Fuad Tabba</name>
<email>tabba@google.com</email>
</author>
<published>2026-02-26T07:55:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ef06fd16d48704eac868441d98d4ef083d8f3d07'/>
<id>ef06fd16d48704eac868441d98d4ef083d8f3d07</id>
<content type='text'>
struct bpf_plt contains a u64 target field. Currently, the BPF JIT
allocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT
buffer.

Because the base address of the JIT buffer can be 4-byte aligned (e.g.,
ending in 0x4 or 0xc), the relative padding logic in build_plt() fails
to ensure that target lands on an 8-byte boundary.

This leads to two issues:
1. UBSAN reports misaligned-access warnings when dereferencing the
   structure.
2. More critically, target is updated concurrently via WRITE_ONCE() in
   bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64,
   64-bit loads/stores are only guaranteed to be single-copy atomic if
   they are 64-bit aligned. A misaligned target risks a torn read,
   causing the JIT to jump to a corrupted address.

Fix this by increasing the allocation alignment requirement to 8 bytes
(sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of
the JIT buffer to an 8-byte boundary, allowing the relative padding math
in build_plt() to correctly align the target field.

Fixes: b2ad54e1533e ("bpf, arm64: Implement bpf_arch_text_poke() for arm64")
Signed-off-by: Fuad Tabba &lt;tabba@google.com&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20260226075525.233321-1-tabba@google.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
struct bpf_plt contains a u64 target field. Currently, the BPF JIT
allocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT
buffer.

Because the base address of the JIT buffer can be 4-byte aligned (e.g.,
ending in 0x4 or 0xc), the relative padding logic in build_plt() fails
to ensure that target lands on an 8-byte boundary.

This leads to two issues:
1. UBSAN reports misaligned-access warnings when dereferencing the
   structure.
2. More critically, target is updated concurrently via WRITE_ONCE() in
   bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64,
   64-bit loads/stores are only guaranteed to be single-copy atomic if
   they are 64-bit aligned. A misaligned target risks a torn read,
   causing the JIT to jump to a corrupted address.

Fix this by increasing the allocation alignment requirement to 8 bytes
(sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of
the JIT buffer to an 8-byte boundary, allowing the relative padding math
in build_plt() to correctly align the target field.

Fixes: b2ad54e1533e ("bpf, arm64: Implement bpf_arch_text_poke() for arm64")
Signed-off-by: Fuad Tabba &lt;tabba@google.com&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20260226075525.233321-1-tabba@google.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Convert 'alloc_obj' family to use the new default GFP_KERNEL argument</title>
<updated>2026-02-22T01:09:51+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2026-02-22T00:37:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bf4afc53b77aeaa48b5409da5c8da6bb4eff7f43'/>
<id>bf4afc53b77aeaa48b5409da5c8da6bb4eff7f43</id>
<content type='text'>
This was done entirely with mindless brute force, using

    git grep -l '\&lt;k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This was done entirely with mindless brute force, using

    git grep -l '\&lt;k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>treewide: Replace kmalloc with kmalloc_obj for non-scalar types</title>
<updated>2026-02-21T09:02:28+00:00</updated>
<author>
<name>Kees Cook</name>
<email>kees@kernel.org</email>
</author>
<published>2026-02-21T07:49:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=69050f8d6d075dc01af7a5f2f550a8067510366f'/>
<id>69050f8d6d075dc01af7a5f2f550a8067510366f</id>
<content type='text'>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'mm-nonmm-stable-2026-02-12-10-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2026-02-12T20:13:01+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2026-02-12T20:13:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=136114e0abf03005e182d75761ab694648e6d388'/>
<id>136114e0abf03005e182d75761ab694648e6d388</id>
<content type='text'>
Pull non-MM updates from Andrew Morton:

 - "ocfs2: give ocfs2 the ability to reclaim suballocator free bg" saves
   disk space by teaching ocfs2 to reclaim suballocator block group
   space (Heming Zhao)

 - "Add ARRAY_END(), and use it to fix off-by-one bugs" adds the
   ARRAY_END() macro and uses it in various places (Alejandro Colomar)

 - "vmcoreinfo: support VMCOREINFO_BYTES larger than PAGE_SIZE" makes
   the vmcore code future-safe, if VMCOREINFO_BYTES ever exceeds the
   page size (Pnina Feder)

 - "kallsyms: Prevent invalid access when showing module buildid" cleans
   up kallsyms code related to module buildid and fixes an invalid
   access crash when printing backtraces (Petr Mladek)

 - "Address page fault in ima_restore_measurement_list()" fixes a
   kexec-related crash that can occur when booting the second-stage
   kernel on x86 (Harshit Mogalapalli)

 - "kho: ABI headers and Documentation updates" updates the kexec
   handover ABI documentation (Mike Rapoport)

 - "Align atomic storage" adds the __aligned attribute to atomic_t and
   atomic64_t definitions to get natural alignment of both types on
   csky, m68k, microblaze, nios2, openrisc and sh (Finn Thain)

 - "kho: clean up page initialization logic" simplifies the page
   initialization logic in kho_restore_page() (Pratyush Yadav)

 - "Unload linux/kernel.h" moves several things out of kernel.h and into
   more appropriate places (Yury Norov)

 - "don't abuse task_struct.group_leader" removes the usage of
   -&gt;group_leader when it is "obviously unnecessary" (Oleg Nesterov)

 - "list private v2 &amp; luo flb" adds some infrastructure improvements to
   the live update orchestrator (Pasha Tatashin)

* tag 'mm-nonmm-stable-2026-02-12-10-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (107 commits)
  watchdog/hardlockup: simplify perf event probe and remove per-cpu dependency
  procfs: fix missing RCU protection when reading real_parent in do_task_stat()
  watchdog/softlockup: fix sample ring index wrap in need_counting_irqs()
  kcsan, compiler_types: avoid duplicate type issues in BPF Type Format
  kho: fix doc for kho_restore_pages()
  tests/liveupdate: add in-kernel liveupdate test
  liveupdate: luo_flb: introduce File-Lifecycle-Bound global state
  liveupdate: luo_file: Use private list
  list: add kunit test for private list primitives
  list: add primitives for private list manipulations
  delayacct: fix uapi timespec64 definition
  panic: add panic_force_cpu= parameter to redirect panic to a specific CPU
  netclassid: use thread_group_leader(p) in update_classid_task()
  RDMA/umem: don't abuse current-&gt;group_leader
  drm/pan*: don't abuse current-&gt;group_leader
  drm/amd: kill the outdated "Only the pthreads threading model is supported" checks
  drm/amdgpu: don't abuse current-&gt;group_leader
  android/binder: use same_thread_group(proc-&gt;tsk, current) in binder_mmap()
  android/binder: don't abuse current-&gt;group_leader
  kho: skip memoryless NUMA nodes when reserving scratch areas
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull non-MM updates from Andrew Morton:

 - "ocfs2: give ocfs2 the ability to reclaim suballocator free bg" saves
   disk space by teaching ocfs2 to reclaim suballocator block group
   space (Heming Zhao)

 - "Add ARRAY_END(), and use it to fix off-by-one bugs" adds the
   ARRAY_END() macro and uses it in various places (Alejandro Colomar)

 - "vmcoreinfo: support VMCOREINFO_BYTES larger than PAGE_SIZE" makes
   the vmcore code future-safe, if VMCOREINFO_BYTES ever exceeds the
   page size (Pnina Feder)

 - "kallsyms: Prevent invalid access when showing module buildid" cleans
   up kallsyms code related to module buildid and fixes an invalid
   access crash when printing backtraces (Petr Mladek)

 - "Address page fault in ima_restore_measurement_list()" fixes a
   kexec-related crash that can occur when booting the second-stage
   kernel on x86 (Harshit Mogalapalli)

 - "kho: ABI headers and Documentation updates" updates the kexec
   handover ABI documentation (Mike Rapoport)

 - "Align atomic storage" adds the __aligned attribute to atomic_t and
   atomic64_t definitions to get natural alignment of both types on
   csky, m68k, microblaze, nios2, openrisc and sh (Finn Thain)

 - "kho: clean up page initialization logic" simplifies the page
   initialization logic in kho_restore_page() (Pratyush Yadav)

 - "Unload linux/kernel.h" moves several things out of kernel.h and into
   more appropriate places (Yury Norov)

 - "don't abuse task_struct.group_leader" removes the usage of
   -&gt;group_leader when it is "obviously unnecessary" (Oleg Nesterov)

 - "list private v2 &amp; luo flb" adds some infrastructure improvements to
   the live update orchestrator (Pasha Tatashin)

* tag 'mm-nonmm-stable-2026-02-12-10-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (107 commits)
  watchdog/hardlockup: simplify perf event probe and remove per-cpu dependency
  procfs: fix missing RCU protection when reading real_parent in do_task_stat()
  watchdog/softlockup: fix sample ring index wrap in need_counting_irqs()
  kcsan, compiler_types: avoid duplicate type issues in BPF Type Format
  kho: fix doc for kho_restore_pages()
  tests/liveupdate: add in-kernel liveupdate test
  liveupdate: luo_flb: introduce File-Lifecycle-Bound global state
  liveupdate: luo_file: Use private list
  list: add kunit test for private list primitives
  list: add primitives for private list manipulations
  delayacct: fix uapi timespec64 definition
  panic: add panic_force_cpu= parameter to redirect panic to a specific CPU
  netclassid: use thread_group_leader(p) in update_classid_task()
  RDMA/umem: don't abuse current-&gt;group_leader
  drm/pan*: don't abuse current-&gt;group_leader
  drm/amd: kill the outdated "Only the pthreads threading model is supported" checks
  drm/amdgpu: don't abuse current-&gt;group_leader
  android/binder: use same_thread_group(proc-&gt;tsk, current) in binder_mmap()
  android/binder: don't abuse current-&gt;group_leader
  kho: skip memoryless NUMA nodes when reserving scratch areas
  ...
</pre>
</div>
</content>
</entry>
</feed>
