<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/tools/testing, branch v6.7-rc3</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux</title>
<updated>2023-11-25T16:43:46+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-11-25T16:43:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2821c393d4fdfc75a96a2fad3bec76cf3107b88a'/>
<id>2821c393d4fdfc75a96a2fad3bec76cf3107b88a</id>
<content type='text'>
Pull arm64 fixes from Catalin Marinas:

 - Fix "rodata=on" not disabling "rodata=full" on arm64

 - Add arm64 make dependency between vmlinuz.efi and Image, leading to
   occasional build failures previously (with parallel building)

 - Add newline to the output formatting of the za-fork kselftest

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: add dependency between vmlinuz.efi and Image
  kselftest/arm64: Fix output formatting for za-fork
  arm64: mm: Fix "rodata=on" when CONFIG_RODATA_FULL_DEFAULT_ENABLED=y
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull arm64 fixes from Catalin Marinas:

 - Fix "rodata=on" not disabling "rodata=full" on arm64

 - Add arm64 make dependency between vmlinuz.efi and Image, leading to
   occasional build failures previously (with parallel building)

 - Add newline to the output formatting of the za-fork kselftest

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: add dependency between vmlinuz.efi and Image
  kselftest/arm64: Fix output formatting for za-fork
  arm64: mm: Fix "rodata=on" when CONFIG_RODATA_FULL_DEFAULT_ENABLED=y
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'net-6.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net</title>
<updated>2023-11-23T18:40:13+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-11-23T18:40:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d3fa86b1a7b4cdc4367acacea16b72e0a200b3d7'/>
<id>d3fa86b1a7b4cdc4367acacea16b72e0a200b3d7</id>
<content type='text'>
Pull networking fixes from Jakub Kicinski:
 "Including fixes from bpf.

  Current release - regressions:

   - Revert "net: r8169: Disable multicast filter for RTL8168H and
     RTL8107E"

   - kselftest: rtnetlink: fix ip route command typo

  Current release - new code bugs:

   - s390/ism: make sure ism driver implies smc protocol in kconfig

   - two build fixes for tools/net

  Previous releases - regressions:

   - rxrpc: couple of ACK/PING/RTT handling fixes

  Previous releases - always broken:

   - bpf: verify bpf_loop() callbacks as if they are called unknown
     number of times

   - improve stability of auto-bonding with Hyper-V

   - account BPF-neigh-redirected traffic in interface statistics

  Misc:

   - net: fill in some more MODULE_DESCRIPTION()s"

* tag 'net-6.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (58 commits)
  tools: ynl: fix duplicate op name in devlink
  tools: ynl: fix header path for nfsd
  net: ipa: fix one GSI register field width
  tls: fix NULL deref on tls_sw_splice_eof() with empty record
  net: axienet: Fix check for partial TX checksum
  vsock/test: fix SEQPACKET message bounds test
  i40e: Fix adding unsupported cloud filters
  ice: restore timestamp configuration after device reset
  ice: unify logic for programming PFINT_TSYN_MSK
  ice: remove ptp_tx ring parameter flag
  amd-xgbe: propagate the correct speed and duplex status
  amd-xgbe: handle the corner-case during tx completion
  amd-xgbe: handle corner-case during sfp hotplug
  net: veth: fix ethtool stats reporting
  octeontx2-pf: Fix ntuple rule creation to direct packet to VF with higher Rx queue than its PF
  net: usb: qmi_wwan: claim interface 4 for ZTE MF290
  Revert "net: r8169: Disable multicast filter for RTL8168H and RTL8107E"
  net/smc: avoid data corruption caused by decline
  nfc: virtual_ncidev: Add variable to check if ndev is running
  dpll: Fix potential msg memleak when genlmsg_put_reply failed
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull networking fixes from Jakub Kicinski:
 "Including fixes from bpf.

  Current release - regressions:

   - Revert "net: r8169: Disable multicast filter for RTL8168H and
     RTL8107E"

   - kselftest: rtnetlink: fix ip route command typo

  Current release - new code bugs:

   - s390/ism: make sure ism driver implies smc protocol in kconfig

   - two build fixes for tools/net

  Previous releases - regressions:

   - rxrpc: couple of ACK/PING/RTT handling fixes

  Previous releases - always broken:

   - bpf: verify bpf_loop() callbacks as if they are called unknown
     number of times

   - improve stability of auto-bonding with Hyper-V

   - account BPF-neigh-redirected traffic in interface statistics

  Misc:

   - net: fill in some more MODULE_DESCRIPTION()s"

* tag 'net-6.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (58 commits)
  tools: ynl: fix duplicate op name in devlink
  tools: ynl: fix header path for nfsd
  net: ipa: fix one GSI register field width
  tls: fix NULL deref on tls_sw_splice_eof() with empty record
  net: axienet: Fix check for partial TX checksum
  vsock/test: fix SEQPACKET message bounds test
  i40e: Fix adding unsupported cloud filters
  ice: restore timestamp configuration after device reset
  ice: unify logic for programming PFINT_TSYN_MSK
  ice: remove ptp_tx ring parameter flag
  amd-xgbe: propagate the correct speed and duplex status
  amd-xgbe: handle the corner-case during tx completion
  amd-xgbe: handle corner-case during sfp hotplug
  net: veth: fix ethtool stats reporting
  octeontx2-pf: Fix ntuple rule creation to direct packet to VF with higher Rx queue than its PF
  net: usb: qmi_wwan: claim interface 4 for ZTE MF290
  Revert "net: r8169: Disable multicast filter for RTL8168H and RTL8107E"
  net/smc: avoid data corruption caused by decline
  nfc: virtual_ncidev: Add variable to check if ndev is running
  dpll: Fix potential msg memleak when genlmsg_put_reply failed
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>vsock/test: fix SEQPACKET message bounds test</title>
<updated>2023-11-23T16:49:16+00:00</updated>
<author>
<name>Arseniy Krasnov</name>
<email>avkrasnov@salutedevices.com</email>
</author>
<published>2023-11-21T21:16:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f0863888f6cfef33e3117dccfe94fa78edf76be4'/>
<id>f0863888f6cfef33e3117dccfe94fa78edf76be4</id>
<content type='text'>
Tune message length calculation to make this test work on machines
where 'getpagesize()' returns &gt;32KB. Now maximum message length is not
hardcoded (on machines above it was smaller than 'getpagesize()' return
value, thus we get negative value and test fails), but calculated at
runtime and always bigger than 'getpagesize()' result. Reproduced on
aarch64 with 64KB page size.

Fixes: 5c338112e48a ("test/vsock: rework message bounds test")
Signed-off-by: Arseniy Krasnov &lt;avkrasnov@salutedevices.com&gt;
Reported-by: Bogdan Marcynkov &lt;bmarcynk@redhat.com&gt;
Reviewed-by: Stefano Garzarella &lt;sgarzare@redhat.com&gt;
Link: https://lore.kernel.org/r/20231121211642.163474-1-avkrasnov@salutedevices.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Tune message length calculation to make this test work on machines
where 'getpagesize()' returns &gt;32KB. Now maximum message length is not
hardcoded (on machines above it was smaller than 'getpagesize()' return
value, thus we get negative value and test fails), but calculated at
runtime and always bigger than 'getpagesize()' result. Reproduced on
aarch64 with 64KB page size.

Fixes: 5c338112e48a ("test/vsock: rework message bounds test")
Signed-off-by: Arseniy Krasnov &lt;avkrasnov@salutedevices.com&gt;
Reported-by: Bogdan Marcynkov &lt;bmarcynk@redhat.com&gt;
Reviewed-by: Stefano Garzarella &lt;sgarzare@redhat.com&gt;
Link: https://lore.kernel.org/r/20231121211642.163474-1-avkrasnov@salutedevices.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>kselftest/arm64: Fix output formatting for za-fork</title>
<updated>2023-11-23T14:16:15+00:00</updated>
<author>
<name>Mark Brown</name>
<email>broonie@kernel.org</email>
</author>
<published>2023-11-16T12:52:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=460e462d22542adfafd8a5bc979437df73f1cbf3'/>
<id>460e462d22542adfafd8a5bc979437df73f1cbf3</id>
<content type='text'>
The za-fork test does not output a newline when reporting the result of
the one test it runs, causing the counts printed by kselftest to be
included in the test name.  Add the newline.

Fixes: 266679ffd867 ("kselftest/arm64: Convert za-fork to use kselftest.h")
Cc: &lt;stable@vger.kernel.org&gt; # 6.4.x
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Link: https://lore.kernel.org/r/20231116-arm64-fix-za-fork-output-v1-1-42c03d4f5759@kernel.org
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The za-fork test does not output a newline when reporting the result of
the one test it runs, causing the counts printed by kselftest to be
included in the test name.  Add the newline.

Fixes: 266679ffd867 ("kselftest/arm64: Convert za-fork to use kselftest.h")
Cc: &lt;stable@vger.kernel.org&gt; # 6.4.x
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Link: https://lore.kernel.org/r/20231116-arm64-fix-za-fork-output-v1-1-42c03d4f5759@kernel.org
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests/bpf: check if max number of bpf_loop iterations is tracked</title>
<updated>2023-11-21T02:36:40+00:00</updated>
<author>
<name>Eduard Zingerman</name>
<email>eddyz87@gmail.com</email>
</author>
<published>2023-11-21T02:07:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=57e2a52deeb12ab84c15c6d0fb93638b5b94001b'/>
<id>57e2a52deeb12ab84c15c6d0fb93638b5b94001b</id>
<content type='text'>
Check that even if bpf_loop() callback simulation does not converge to
a specific state, verification could proceed via "brute force"
simulation of maximal number of callback calls.

Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-12-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Check that even if bpf_loop() callback simulation does not converge to
a specific state, verification could proceed via "brute force"
simulation of maximal number of callback calls.

Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-12-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: keep track of max number of bpf_loop callback iterations</title>
<updated>2023-11-21T02:36:40+00:00</updated>
<author>
<name>Eduard Zingerman</name>
<email>eddyz87@gmail.com</email>
</author>
<published>2023-11-21T02:07:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bb124da69c47dd98d69361ec13244ece50bec63e'/>
<id>bb124da69c47dd98d69361ec13244ece50bec63e</id>
<content type='text'>
In some cases verifier can't infer convergence of the bpf_loop()
iteration. E.g. for the following program:

    static int cb(__u32 idx, struct num_context* ctx)
    {
        ctx-&gt;i++;
        return 0;
    }

    SEC("?raw_tp")
    int prog(void *_)
    {
        struct num_context ctx = { .i = 0 };
        __u8 choice_arr[2] = { 0, 1 };

        bpf_loop(2, cb, &amp;ctx, 0);
        return choice_arr[ctx.i];
    }

Each 'cb' simulation would eventually return to 'prog' and reach
'return choice_arr[ctx.i]' statement. At which point ctx.i would be
marked precise, thus forcing verifier to track multitude of separate
states with {.i=0}, {.i=1}, ... at bpf_loop() callback entry.

This commit allows "brute force" handling for such cases by limiting
number of callback body simulations using 'umax' value of the first
bpf_loop() parameter.

For this, extend bpf_func_state with 'callback_depth' field.
Increment this field when callback visiting state is pushed to states
traversal stack. For frame #N it's 'callback_depth' field counts how
many times callback with frame depth N+1 had been executed.
Use bpf_func_state specifically to allow independent tracking of
callback depths when multiple nested bpf_loop() calls are present.

Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-11-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In some cases verifier can't infer convergence of the bpf_loop()
iteration. E.g. for the following program:

    static int cb(__u32 idx, struct num_context* ctx)
    {
        ctx-&gt;i++;
        return 0;
    }

    SEC("?raw_tp")
    int prog(void *_)
    {
        struct num_context ctx = { .i = 0 };
        __u8 choice_arr[2] = { 0, 1 };

        bpf_loop(2, cb, &amp;ctx, 0);
        return choice_arr[ctx.i];
    }

Each 'cb' simulation would eventually return to 'prog' and reach
'return choice_arr[ctx.i]' statement. At which point ctx.i would be
marked precise, thus forcing verifier to track multitude of separate
states with {.i=0}, {.i=1}, ... at bpf_loop() callback entry.

This commit allows "brute force" handling for such cases by limiting
number of callback body simulations using 'umax' value of the first
bpf_loop() parameter.

For this, extend bpf_func_state with 'callback_depth' field.
Increment this field when callback visiting state is pushed to states
traversal stack. For frame #N it's 'callback_depth' field counts how
many times callback with frame depth N+1 had been executed.
Use bpf_func_state specifically to allow independent tracking of
callback depths when multiple nested bpf_loop() calls are present.

Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-11-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests/bpf: test widening for iterating callbacks</title>
<updated>2023-11-21T02:36:40+00:00</updated>
<author>
<name>Eduard Zingerman</name>
<email>eddyz87@gmail.com</email>
</author>
<published>2023-11-21T02:06:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9f3330aa644d6d979eb064c46e85c62d4b4eac75'/>
<id>9f3330aa644d6d979eb064c46e85c62d4b4eac75</id>
<content type='text'>
A test case to verify that imprecise scalars widening is applied to
callback entering state, when callback call is simulated repeatedly.

Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-10-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
A test case to verify that imprecise scalars widening is applied to
callback entering state, when callback call is simulated repeatedly.

Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-10-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests/bpf: tests for iterating callbacks</title>
<updated>2023-11-21T02:36:40+00:00</updated>
<author>
<name>Eduard Zingerman</name>
<email>eddyz87@gmail.com</email>
</author>
<published>2023-11-21T02:06:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=958465e217dbf5fc6677d42d8827fb3073d86afd'/>
<id>958465e217dbf5fc6677d42d8827fb3073d86afd</id>
<content type='text'>
A set of test cases to check behavior of callback handling logic,
check if verifier catches the following situations:
- program not safe on second callback iteration;
- program not safe on zero callback iterations;
- infinite loop inside a callback.

Verify that callback logic works for bpf_loop, bpf_for_each_map_elem,
bpf_user_ringbuf_drain, bpf_find_vma.

Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-8-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
A set of test cases to check behavior of callback handling logic,
check if verifier catches the following situations:
- program not safe on second callback iteration;
- program not safe on zero callback iterations;
- infinite loop inside a callback.

Verify that callback logic works for bpf_loop, bpf_for_each_map_elem,
bpf_user_ringbuf_drain, bpf_find_vma.

Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-8-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bpf: verify callbacks as if they are called unknown number of times</title>
<updated>2023-11-21T02:35:44+00:00</updated>
<author>
<name>Eduard Zingerman</name>
<email>eddyz87@gmail.com</email>
</author>
<published>2023-11-21T02:06:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ab5cfac139ab8576fb54630d4cca23c3e690ee90'/>
<id>ab5cfac139ab8576fb54630d4cca23c3e690ee90</id>
<content type='text'>
Prior to this patch callbacks were handled as regular function calls,
execution of callback body was modeled exactly once.
This patch updates callbacks handling logic as follows:
- introduces a function push_callback_call() that schedules callback
  body verification in env-&gt;head stack;
- updates prepare_func_exit() to reschedule callback body verification
  upon BPF_EXIT;
- as calls to bpf_*_iter_next(), calls to callback invoking functions
  are marked as checkpoints;
- is_state_visited() is updated to stop callback based iteration when
  some identical parent state is found.

Paths with callback function invoked zero times are now verified first,
which leads to necessity to modify some selftests:
- the following negative tests required adding release/unlock/drop
  calls to avoid previously masked unrelated error reports:
  - cb_refs.c:underflow_prog
  - exceptions_fail.c:reject_rbtree_add_throw
  - exceptions_fail.c:reject_with_cp_reference
- the following precision tracking selftests needed change in expected
  log trace:
  - verifier_subprog_precision.c:callback_result_precise
    (note: r0 precision is no longer propagated inside callback and
           I think this is a correct behavior)
  - verifier_subprog_precision.c:parent_callee_saved_reg_precise_with_callback
  - verifier_subprog_precision.c:parent_stack_slot_precise_with_callback

Reported-by: Andrew Werner &lt;awerner32@gmail.com&gt;
Closes: https://lore.kernel.org/bpf/CA+vRuzPChFNXmouzGG+wsy=6eMcfr1mFG0F3g7rbg-sedGKW3w@mail.gmail.com/
Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-7-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Prior to this patch callbacks were handled as regular function calls,
execution of callback body was modeled exactly once.
This patch updates callbacks handling logic as follows:
- introduces a function push_callback_call() that schedules callback
  body verification in env-&gt;head stack;
- updates prepare_func_exit() to reschedule callback body verification
  upon BPF_EXIT;
- as calls to bpf_*_iter_next(), calls to callback invoking functions
  are marked as checkpoints;
- is_state_visited() is updated to stop callback based iteration when
  some identical parent state is found.

Paths with callback function invoked zero times are now verified first,
which leads to necessity to modify some selftests:
- the following negative tests required adding release/unlock/drop
  calls to avoid previously masked unrelated error reports:
  - cb_refs.c:underflow_prog
  - exceptions_fail.c:reject_rbtree_add_throw
  - exceptions_fail.c:reject_with_cp_reference
- the following precision tracking selftests needed change in expected
  log trace:
  - verifier_subprog_precision.c:callback_result_precise
    (note: r0 precision is no longer propagated inside callback and
           I think this is a correct behavior)
  - verifier_subprog_precision.c:parent_callee_saved_reg_precise_with_callback
  - verifier_subprog_precision.c:parent_stack_slot_precise_with_callback

Reported-by: Andrew Werner &lt;awerner32@gmail.com&gt;
Closes: https://lore.kernel.org/bpf/CA+vRuzPChFNXmouzGG+wsy=6eMcfr1mFG0F3g7rbg-sedGKW3w@mail.gmail.com/
Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-7-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests/bpf: fix bpf_loop_bench for new callback verification scheme</title>
<updated>2023-11-21T02:33:35+00:00</updated>
<author>
<name>Eduard Zingerman</name>
<email>eddyz87@gmail.com</email>
</author>
<published>2023-11-21T02:06:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f40bfd1679446b22d321e64a1fa98b7d07d2be08'/>
<id>f40bfd1679446b22d321e64a1fa98b7d07d2be08</id>
<content type='text'>
This is a preparatory change. A follow-up patch "bpf: verify callbacks
as if they are called unknown number of times" changes logic for
callbacks handling. While previously callbacks were verified as a
single function call, new scheme takes into account that callbacks
could be executed unknown number of times.

This has dire implications for bpf_loop_bench:

    SEC("fentry/" SYS_PREFIX "sys_getpgid")
    int benchmark(void *ctx)
    {
            for (int i = 0; i &lt; 1000; i++) {
                    bpf_loop(nr_loops, empty_callback, NULL, 0);
                    __sync_add_and_fetch(&amp;hits, nr_loops);
            }
            return 0;
    }

W/o callbacks change verifier sees it as a 1000 calls to
empty_callback(). However, with callbacks change things become
exponential:
- i=0: state exploring empty_callback is scheduled with i=0 (a);
- i=1: state exploring empty_callback is scheduled with i=1;
  ...
- i=999: state exploring empty_callback is scheduled with i=999;
- state (a) is popped from stack;
- i=1: state exploring empty_callback is scheduled with i=1;
  ...

Avoid this issue by rewriting outer loop as bpf_loop().
Unfortunately, this adds a function call to a loop at runtime, which
negatively affects performance:

            throughput               latency
   before:  149.919 ± 0.168 M ops/s, 6.670 ns/op
   after :  137.040 ± 0.187 M ops/s, 7.297 ns/op

Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is a preparatory change. A follow-up patch "bpf: verify callbacks
as if they are called unknown number of times" changes logic for
callbacks handling. While previously callbacks were verified as a
single function call, new scheme takes into account that callbacks
could be executed unknown number of times.

This has dire implications for bpf_loop_bench:

    SEC("fentry/" SYS_PREFIX "sys_getpgid")
    int benchmark(void *ctx)
    {
            for (int i = 0; i &lt; 1000; i++) {
                    bpf_loop(nr_loops, empty_callback, NULL, 0);
                    __sync_add_and_fetch(&amp;hits, nr_loops);
            }
            return 0;
    }

W/o callbacks change verifier sees it as a 1000 calls to
empty_callback(). However, with callbacks change things become
exponential:
- i=0: state exploring empty_callback is scheduled with i=0 (a);
- i=1: state exploring empty_callback is scheduled with i=1;
  ...
- i=999: state exploring empty_callback is scheduled with i=999;
- state (a) is popped from stack;
- i=1: state exploring empty_callback is scheduled with i=1;
  ...

Avoid this issue by rewriting outer loop as bpf_loop().
Unfortunately, this adds a function call to a loop at runtime, which
negatively affects performance:

            throughput               latency
   before:  149.919 ± 0.168 M ops/s, 6.670 ns/op
   after :  137.040 ± 0.187 M ops/s, 7.297 ns/op

Acked-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Signed-off-by: Eduard Zingerman &lt;eddyz87@gmail.com&gt;
Link: https://lore.kernel.org/r/20231121020701.26440-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
