<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/riscv/Makefile, branch master</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>riscv: Remove support for XIP kernel</title>
<updated>2026-04-05T00:42:44+00:00</updated>
<author>
<name>Nam Cao</name>
<email>namcao@linutronix.de</email>
</author>
<published>2026-04-04T01:28:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9b3a2be84803cf18c4b4d1efc695991f0daa153c'/>
<id>9b3a2be84803cf18c4b4d1efc695991f0daa153c</id>
<content type='text'>
XIP has a history of being broken for long periods of time. In 2023, it was
broken for 18 months before getting fixed [1]. In 2024 it was 4 months [2].

And now it is broken again since commit a44fb5722199 ("riscv: Add runtime
constant support"), 10 months ago.

These are clear signs that XIP feature is not being used.

I occasionally looked after XIP, but mostly because I was bored and had
nothing better to do.

Remove XIP support. Revert is possible if someone shows up complaining.

Link: https://lore.kernel.org/linux-riscv/20231212-customary-hardcover-e19462bf8e75@wendy/ [1]
Link: https://lore.kernel.org/linux-riscv/20240526110104.470429-1-namcao@linutronix.de/ [2]
Signed-off-by: Nam Cao &lt;namcao@linutronix.de&gt;
Cc: Frederik Haxel &lt;haxel@fzi.de&gt;
Cc: Vitaly Wool &lt;vitaly.wool@konsulko.com&gt;
Reviewed-by: Jisheng Zhang &lt;jszhang@kernel.org&gt;
Acked-by: Conor Dooley &lt;conor.dooley@microchip.com&gt;
Link: https://patch.msgid.link/20260202115403.2119218-1-namcao@linutronix.de
[pjw@kernel.org: updated to apply]
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
XIP has a history of being broken for long periods of time. In 2023, it was
broken for 18 months before getting fixed [1]. In 2024 it was 4 months [2].

And now it is broken again since commit a44fb5722199 ("riscv: Add runtime
constant support"), 10 months ago.

These are clear signs that XIP feature is not being used.

I occasionally looked after XIP, but mostly because I was bored and had
nothing better to do.

Remove XIP support. Revert is possible if someone shows up complaining.

Link: https://lore.kernel.org/linux-riscv/20231212-customary-hardcover-e19462bf8e75@wendy/ [1]
Link: https://lore.kernel.org/linux-riscv/20240526110104.470429-1-namcao@linutronix.de/ [2]
Signed-off-by: Nam Cao &lt;namcao@linutronix.de&gt;
Cc: Frederik Haxel &lt;haxel@fzi.de&gt;
Cc: Vitaly Wool &lt;vitaly.wool@konsulko.com&gt;
Reviewed-by: Jisheng Zhang &lt;jszhang@kernel.org&gt;
Acked-by: Conor Dooley &lt;conor.dooley@microchip.com&gt;
Link: https://patch.msgid.link/20260202115403.2119218-1-namcao@linutronix.de
[pjw@kernel.org: updated to apply]
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: Simplify assignment for UTS_MACHINE</title>
<updated>2026-04-05T00:42:40+00:00</updated>
<author>
<name>Uwe Kleine-König</name>
<email>u.kleine-koenig@baylibre.com</email>
</author>
<published>2026-04-05T00:42:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c8d0c36d852ccd7caf9d5a44f3090f80a060c28d'/>
<id>c8d0c36d852ccd7caf9d5a44f3090f80a060c28d</id>
<content type='text'>
The BITS variable conveniently allows to simplify the assignment for
UTS_MACHINE.

Signed-off-by: Uwe Kleine-König (The Capable Hub) &lt;u.kleine-koenig@baylibre.com&gt;
Link: https://patch.msgid.link/20260313164012.1153936-2-u.kleine-koenig@baylibre.com
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The BITS variable conveniently allows to simplify the assignment for
UTS_MACHINE.

Signed-off-by: Uwe Kleine-König (The Capable Hub) &lt;u.kleine-koenig@baylibre.com&gt;
Link: https://patch.msgid.link/20260313164012.1153936-2-u.kleine-koenig@baylibre.com
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arch/riscv: add dual vdso creation logic and select vdso based on hw</title>
<updated>2026-01-29T09:38:40+00:00</updated>
<author>
<name>Deepak Gupta</name>
<email>debug@rivosinc.com</email>
</author>
<published>2026-01-26T04:09:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ccad8c1336b6511e3c7ca5c02f797b1fd2cf67e1'/>
<id>ccad8c1336b6511e3c7ca5c02f797b1fd2cf67e1</id>
<content type='text'>
Shadow stack instructions are taken from the Zimop ISA extension,
which is mandated on RVA23. Any userspace with shadow stack
instructions in it will fault on hardware that doesn't have support
for Zimop.  Thus, a shadow stack-enabled userspace can't be run on
hardware that doesn't support Zimop.

It's not known how Linux userspace providers will respond to this kind
of binary fragmentation.  In order to keep kernel portable across
different hardware, 'arch/riscv/kernel/vdso_cfi' is created which has
Makefile logic to compile 'arch/riscv/kernel/vdso' sources with CFI
flags, and 'arch/riscv/kernel/vdso.c' is modified to select the
appropriate vdso depending on whether the underlying CPU implements
the Zimop extension. Since the offset of vdso symbols will change due
to having two different vdso binaries, there is added logic to include
a new generated vdso offset header and dynamically select the offset
(like for rt_sigreturn).

Signed-off-by: Deepak Gupta &lt;debug@rivosinc.com&gt;
Acked-by: Charles Mirabile &lt;cmirabil@redhat.com&gt;
Tested-by: Andreas Korb &lt;andreas.korb@aisec.fraunhofer.de&gt; # QEMU, custom CVA6
Tested-by: Valentin Haudiquet &lt;valentin.haudiquet@canonical.com&gt;
Link: https://patch.msgid.link/20251112-v5_user_cfi_series-v23-24-b55691eacf4f@rivosinc.com
[pjw@kernel.org: cleaned up patch description]
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Shadow stack instructions are taken from the Zimop ISA extension,
which is mandated on RVA23. Any userspace with shadow stack
instructions in it will fault on hardware that doesn't have support
for Zimop.  Thus, a shadow stack-enabled userspace can't be run on
hardware that doesn't support Zimop.

It's not known how Linux userspace providers will respond to this kind
of binary fragmentation.  In order to keep kernel portable across
different hardware, 'arch/riscv/kernel/vdso_cfi' is created which has
Makefile logic to compile 'arch/riscv/kernel/vdso' sources with CFI
flags, and 'arch/riscv/kernel/vdso.c' is modified to select the
appropriate vdso depending on whether the underlying CPU implements
the Zimop extension. Since the offset of vdso symbols will change due
to having two different vdso binaries, there is added logic to include
a new generated vdso offset header and dynamically select the offset
(like for rt_sigreturn).

Signed-off-by: Deepak Gupta &lt;debug@rivosinc.com&gt;
Acked-by: Charles Mirabile &lt;cmirabil@redhat.com&gt;
Tested-by: Andreas Korb &lt;andreas.korb@aisec.fraunhofer.de&gt; # QEMU, custom CVA6
Tested-by: Valentin Haudiquet &lt;valentin.haudiquet@canonical.com&gt;
Link: https://patch.msgid.link/20251112-v5_user_cfi_series-v23-24-b55691eacf4f@rivosinc.com
[pjw@kernel.org: cleaned up patch description]
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arch/riscv: compile vdso with landing pad and shadow stack note</title>
<updated>2026-01-29T09:38:40+00:00</updated>
<author>
<name>Jim Shu</name>
<email>jim.shu@sifive.com</email>
</author>
<published>2026-01-26T04:09:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=37f57bd3faeac92e898c3381355f4fd2b6a80901'/>
<id>37f57bd3faeac92e898c3381355f4fd2b6a80901</id>
<content type='text'>
User mode tasks compiled with Zicfilp may call indirectly into the
vdso (like hwprobe indirect calls). Add support for compiling landing
pads into the vdso. Landing pad instructions in the vdso will be
no-ops for tasks which have not enabled landing pads. Furthermore, add
support for the C sources of the vdso to be compiled with shadow stack
and landing pads enabled as well.

Landing pad and shadow stack instructions are emitted only when the
VDSO_CFI cflags option is defined during compile.

Signed-off-by: Jim Shu &lt;jim.shu@sifive.com&gt;
Reviewed-by: Zong Li &lt;zong.li@sifive.com&gt;
Signed-off-by: Deepak Gupta &lt;debug@rivosinc.com&gt;
Tested-by: Andreas Korb &lt;andreas.korb@aisec.fraunhofer.de&gt; # QEMU, custom CVA6
Tested-by: Valentin Haudiquet &lt;valentin.haudiquet@canonical.com&gt;
Link: https://patch.msgid.link/20251112-v5_user_cfi_series-v23-23-b55691eacf4f@rivosinc.com
[pjw@kernel.org: cleaned up patch description, issues reported by checkpatch]
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
User mode tasks compiled with Zicfilp may call indirectly into the
vdso (like hwprobe indirect calls). Add support for compiling landing
pads into the vdso. Landing pad instructions in the vdso will be
no-ops for tasks which have not enabled landing pads. Furthermore, add
support for the C sources of the vdso to be compiled with shadow stack
and landing pads enabled as well.

Landing pad and shadow stack instructions are emitted only when the
VDSO_CFI cflags option is defined during compile.

Signed-off-by: Jim Shu &lt;jim.shu@sifive.com&gt;
Reviewed-by: Zong Li &lt;zong.li@sifive.com&gt;
Signed-off-by: Deepak Gupta &lt;debug@rivosinc.com&gt;
Tested-by: Andreas Korb &lt;andreas.korb@aisec.fraunhofer.de&gt; # QEMU, custom CVA6
Tested-by: Valentin Haudiquet &lt;valentin.haudiquet@canonical.com&gt;
Link: https://patch.msgid.link/20251112-v5_user_cfi_series-v23-23-b55691eacf4f@rivosinc.com
[pjw@kernel.org: cleaned up patch description, issues reported by checkpatch]
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: Remove redundant judgment for the default build target</title>
<updated>2025-11-08T00:39:07+00:00</updated>
<author>
<name>Feng Jiang</name>
<email>jiangfeng@kylinos.cn</email>
</author>
<published>2025-10-29T09:44:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5e8632987dd1882ed4d1e1039032ab1b0c1ec12b'/>
<id>5e8632987dd1882ed4d1e1039032ab1b0c1ec12b</id>
<content type='text'>
The value of KBUILD_IMAGE is derived from $(boot-image-y),
so there's no need for redundant checks before this.

Signed-off-by: Feng Jiang &lt;jiangfeng@kylinos.cn&gt;
Reviewed-by: Emil Renner Berthing &lt;emil.renner.berthing@canonical.com&gt;
Link: https://lore.kernel.org/r/20251029094429.553842-2-jiangfeng@kylinos.cn
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The value of KBUILD_IMAGE is derived from $(boot-image-y),
so there's no need for redundant checks before this.

Signed-off-by: Feng Jiang &lt;jiangfeng@kylinos.cn&gt;
Reviewed-by: Emil Renner Berthing &lt;emil.renner.berthing@canonical.com&gt;
Link: https://lore.kernel.org/r/20251029094429.553842-2-jiangfeng@kylinos.cn
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: Build loader.bin exclusively for Canaan K210</title>
<updated>2025-11-08T00:39:06+00:00</updated>
<author>
<name>Feng Jiang</name>
<email>jiangfeng@kylinos.cn</email>
</author>
<published>2025-10-29T09:44:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3ad1b71fdc5707d14332d9ae710a237de936be9b'/>
<id>3ad1b71fdc5707d14332d9ae710a237de936be9b</id>
<content type='text'>
According to the explanation in commit ef10bdf9c3e6 ("riscv:
Kconfig.socs: Split ARCH_CANAAN and SOC_CANAAN_K210"),
loader.bin is a special feature of the Canaan K210 and
is not applicable to other SoCs.

Fixes: e79dfcbfb902 ("riscv: make image compression configurable")
Signed-off-by: Feng Jiang &lt;jiangfeng@kylinos.cn&gt;
Reviewed-by: Emil Renner Berthing &lt;emil.renner.berthing@canonical.com&gt;
Link: https://lore.kernel.org/r/20251029094429.553842-1-jiangfeng@kylinos.cn
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
According to the explanation in commit ef10bdf9c3e6 ("riscv:
Kconfig.socs: Split ARCH_CANAAN and SOC_CANAAN_K210"),
loader.bin is a special feature of the Canaan K210 and
is not applicable to other SoCs.

Fixes: e79dfcbfb902 ("riscv: make image compression configurable")
Signed-off-by: Feng Jiang &lt;jiangfeng@kylinos.cn&gt;
Reviewed-by: Emil Renner Berthing &lt;emil.renner.berthing@canonical.com&gt;
Link: https://lore.kernel.org/r/20251029094429.553842-1-jiangfeng@kylinos.cn
Signed-off-by: Paul Walmsley &lt;pjw@kernel.org&gt;</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: Unconditionally use linker relaxation</title>
<updated>2025-08-28T23:58:45+00:00</updated>
<author>
<name>Nathan Chancellor</name>
<email>nathan@kernel.org</email>
</author>
<published>2025-08-21T21:15:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7ccbe91796d7bb584a00833cb59ef7d4575ba784'/>
<id>7ccbe91796d7bb584a00833cb59ef7d4575ba784</id>
<content type='text'>
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, CONFIG_RISCV_USE_LINKER_RELAXATION will
always be enabled, so it can be removed.

Acked-by: Alexandre Ghiti &lt;alexghiti@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20250821-bump-min-llvm-ver-15-v2-8-635f3294e5f0@kernel.org
Signed-off-by: Nathan Chancellor &lt;nathan@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, CONFIG_RISCV_USE_LINKER_RELAXATION will
always be enabled, so it can be removed.

Acked-by: Alexandre Ghiti &lt;alexghiti@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20250821-bump-min-llvm-ver-15-v2-8-635f3294e5f0@kernel.org
Signed-off-by: Nathan Chancellor &lt;nathan@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: Implement HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS</title>
<updated>2025-06-05T18:09:30+00:00</updated>
<author>
<name>Puranjay Mohan</name>
<email>puranjay12@gmail.com</email>
</author>
<published>2025-04-07T18:08:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c217157bcd1df434fdeaeb24b7c25ec31e15cf4a'/>
<id>c217157bcd1df434fdeaeb24b7c25ec31e15cf4a</id>
<content type='text'>
This patch enables support for DYNAMIC_FTRACE_WITH_CALL_OPS on RISC-V.
This allows each ftrace callsite to provide an ftrace_ops to the common
ftrace trampoline, allowing each callsite to invoke distinct tracer
functions without the need to fall back to list processing or to
allocate custom trampolines for each callsite. This significantly speeds
up cases where multiple distinct trace functions are used and callsites
are mostly traced by a single tracer.

The idea and most of the implementation is taken from the ARM64's
implementation of the same feature. The idea is to place a pointer to
the ftrace_ops as a literal at a fixed offset from the function entry
point, which can be recovered by the common ftrace trampoline.

We use -fpatchable-function-entry to reserve 8 bytes above the function
entry by emitting 2 4 byte or 4 2 byte  nops depending on the presence of
CONFIG_RISCV_ISA_C. These 8 bytes are patched at runtime with a pointer
to the associated ftrace_ops for that callsite. Functions are aligned to
8 bytes to make sure that the accesses to this literal are atomic.

This approach allows for directly invoking ftrace_ops::func even for
ftrace_ops which are dynamically-allocated (or part of a module),
without going via ftrace_ops_list_func.

We've benchamrked this with the ftrace_ops sample module on Spacemit K1
Jupiter:

Without this patch:

baseline (Linux rivos 6.14.0-09584-g7d06015d936c #3 SMP Sat Mar 29
+-----------------------+-----------------+----------------------------+
|  Number of tracers    | Total time (ns) | Per-call average time      |
|-----------------------+-----------------+----------------------------|
| Relevant | Irrelevant |    100000 calls | Total (ns) | Overhead (ns) |
|----------+------------+-----------------+------------+---------------|
|        0 |          0 |        1357958 |          13 |             - |
|        0 |          1 |        1302375 |          13 |             - |
|        0 |          2 |        1302375 |          13 |             - |
|        0 |         10 |        1379084 |          13 |             - |
|        0 |        100 |        1302458 |          13 |             - |
|        0 |        200 |        1302333 |          13 |             - |
|----------+------------+-----------------+------------+---------------|
|        1 |          0 |       13677833 |         136 |           123 |
|        1 |          1 |       18500916 |         185 |           172 |
|        1 |          2 |       22856459 |         228 |           215 |
|        1 |         10 |       58824709 |         588 |           575 |
|        1 |        100 |      505141584 |        5051 |          5038 |
|        1 |        200 |     1580473126 |       15804 |         15791 |
|----------+------------+-----------------+------------+---------------|
|        1 |          0 |       13561000 |         135 |           122 |
|        2 |          0 |       19707292 |         197 |           184 |
|       10 |          0 |       67774750 |         677 |           664 |
|      100 |          0 |      714123125 |        7141 |          7128 |
|      200 |          0 |     1918065668 |       19180 |         19167 |
+----------+------------+-----------------+------------+---------------+

Note: per-call overhead is estimated relative to the baseline case with
0 relevant tracers and 0 irrelevant tracers.

With this patch:

v4-rc4 (Linux rivos 6.14.0-09598-gd75747611c93 #4 SMP Sat Mar 29
+-----------------------+-----------------+----------------------------+
|  Number of tracers    | Total time (ns) | Per-call average time      |
|-----------------------+-----------------+----------------------------|
| Relevant | Irrelevant |    100000 calls | Total (ns) | Overhead (ns) |
|----------+------------+-----------------+------------+---------------|
|        0 |          0 |         1459917 |         14 |             - |
|        0 |          1 |         1408000 |         14 |             - |
|        0 |          2 |         1383792 |         13 |             - |
|        0 |         10 |         1430709 |         14 |             - |
|        0 |        100 |         1383791 |         13 |             - |
|        0 |        200 |         1383750 |         13 |             - |
|----------+------------+-----------------+------------+---------------|
|        1 |          0 |         5238041 |         52 |            38 |
|        1 |          1 |         5228542 |         52 |            38 |
|        1 |          2 |         5325917 |         53 |            40 |
|        1 |         10 |         5299667 |         52 |            38 |
|        1 |        100 |         5245250 |         52 |            39 |
|        1 |        200 |         5238459 |         52 |            39 |
|----------+------------+-----------------+------------+---------------|
|        1 |          0 |         5239083 |         52 |            38 |
|        2 |          0 |        19449417 |        194 |           181 |
|       10 |          0 |        67718584 |        677 |           663 |
|      100 |          0 |       709840708 |       7098 |          7085 |
|      200 |          0 |      2203580626 |      22035 |         22022 |
+----------+------------+-----------------+------------+---------------+

Note: per-call overhead is estimated relative to the baseline case with
0 relevant tracers and 0 irrelevant tracers.

As can be seen from the above:

 a) Whenever there is a single relevant tracer function associated with a
    tracee, the overhead of invoking the tracer is constant, and does not
    scale with the number of tracers which are *not* associated with that
    tracee.

 b) The overhead for a single relevant tracer has dropped to ~1/3 of the
    overhead prior to this series (from 122ns to 38ns). This is largely
    due to permitting calls to dynamically-allocated ftrace_ops without
    going through ftrace_ops_list_func.

Signed-off-by: Puranjay Mohan &lt;puranjay12@gmail.com&gt;

[update kconfig, asm, refactor]

Signed-off-by: Andy Chiu &lt;andybnac@gmail.com&gt;
Tested-by: Björn Töpel &lt;bjorn@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20250407180838.42877-10-andybnac@gmail.com
Signed-off-by: Alexandre Ghiti &lt;alexghiti@rivosinc.com&gt;
Signed-off-by: Palmer Dabbelt &lt;palmer@dabbelt.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch enables support for DYNAMIC_FTRACE_WITH_CALL_OPS on RISC-V.
This allows each ftrace callsite to provide an ftrace_ops to the common
ftrace trampoline, allowing each callsite to invoke distinct tracer
functions without the need to fall back to list processing or to
allocate custom trampolines for each callsite. This significantly speeds
up cases where multiple distinct trace functions are used and callsites
are mostly traced by a single tracer.

The idea and most of the implementation is taken from the ARM64's
implementation of the same feature. The idea is to place a pointer to
the ftrace_ops as a literal at a fixed offset from the function entry
point, which can be recovered by the common ftrace trampoline.

We use -fpatchable-function-entry to reserve 8 bytes above the function
entry by emitting 2 4 byte or 4 2 byte  nops depending on the presence of
CONFIG_RISCV_ISA_C. These 8 bytes are patched at runtime with a pointer
to the associated ftrace_ops for that callsite. Functions are aligned to
8 bytes to make sure that the accesses to this literal are atomic.

This approach allows for directly invoking ftrace_ops::func even for
ftrace_ops which are dynamically-allocated (or part of a module),
without going via ftrace_ops_list_func.

We've benchamrked this with the ftrace_ops sample module on Spacemit K1
Jupiter:

Without this patch:

baseline (Linux rivos 6.14.0-09584-g7d06015d936c #3 SMP Sat Mar 29
+-----------------------+-----------------+----------------------------+
|  Number of tracers    | Total time (ns) | Per-call average time      |
|-----------------------+-----------------+----------------------------|
| Relevant | Irrelevant |    100000 calls | Total (ns) | Overhead (ns) |
|----------+------------+-----------------+------------+---------------|
|        0 |          0 |        1357958 |          13 |             - |
|        0 |          1 |        1302375 |          13 |             - |
|        0 |          2 |        1302375 |          13 |             - |
|        0 |         10 |        1379084 |          13 |             - |
|        0 |        100 |        1302458 |          13 |             - |
|        0 |        200 |        1302333 |          13 |             - |
|----------+------------+-----------------+------------+---------------|
|        1 |          0 |       13677833 |         136 |           123 |
|        1 |          1 |       18500916 |         185 |           172 |
|        1 |          2 |       22856459 |         228 |           215 |
|        1 |         10 |       58824709 |         588 |           575 |
|        1 |        100 |      505141584 |        5051 |          5038 |
|        1 |        200 |     1580473126 |       15804 |         15791 |
|----------+------------+-----------------+------------+---------------|
|        1 |          0 |       13561000 |         135 |           122 |
|        2 |          0 |       19707292 |         197 |           184 |
|       10 |          0 |       67774750 |         677 |           664 |
|      100 |          0 |      714123125 |        7141 |          7128 |
|      200 |          0 |     1918065668 |       19180 |         19167 |
+----------+------------+-----------------+------------+---------------+

Note: per-call overhead is estimated relative to the baseline case with
0 relevant tracers and 0 irrelevant tracers.

With this patch:

v4-rc4 (Linux rivos 6.14.0-09598-gd75747611c93 #4 SMP Sat Mar 29
+-----------------------+-----------------+----------------------------+
|  Number of tracers    | Total time (ns) | Per-call average time      |
|-----------------------+-----------------+----------------------------|
| Relevant | Irrelevant |    100000 calls | Total (ns) | Overhead (ns) |
|----------+------------+-----------------+------------+---------------|
|        0 |          0 |         1459917 |         14 |             - |
|        0 |          1 |         1408000 |         14 |             - |
|        0 |          2 |         1383792 |         13 |             - |
|        0 |         10 |         1430709 |         14 |             - |
|        0 |        100 |         1383791 |         13 |             - |
|        0 |        200 |         1383750 |         13 |             - |
|----------+------------+-----------------+------------+---------------|
|        1 |          0 |         5238041 |         52 |            38 |
|        1 |          1 |         5228542 |         52 |            38 |
|        1 |          2 |         5325917 |         53 |            40 |
|        1 |         10 |         5299667 |         52 |            38 |
|        1 |        100 |         5245250 |         52 |            39 |
|        1 |        200 |         5238459 |         52 |            39 |
|----------+------------+-----------------+------------+---------------|
|        1 |          0 |         5239083 |         52 |            38 |
|        2 |          0 |        19449417 |        194 |           181 |
|       10 |          0 |        67718584 |        677 |           663 |
|      100 |          0 |       709840708 |       7098 |          7085 |
|      200 |          0 |      2203580626 |      22035 |         22022 |
+----------+------------+-----------------+------------+---------------+

Note: per-call overhead is estimated relative to the baseline case with
0 relevant tracers and 0 irrelevant tracers.

As can be seen from the above:

 a) Whenever there is a single relevant tracer function associated with a
    tracee, the overhead of invoking the tracer is constant, and does not
    scale with the number of tracers which are *not* associated with that
    tracee.

 b) The overhead for a single relevant tracer has dropped to ~1/3 of the
    overhead prior to this series (from 122ns to 38ns). This is largely
    due to permitting calls to dynamically-allocated ftrace_ops without
    going through ftrace_ops_list_func.

Signed-off-by: Puranjay Mohan &lt;puranjay12@gmail.com&gt;

[update kconfig, asm, refactor]

Signed-off-by: Andy Chiu &lt;andybnac@gmail.com&gt;
Tested-by: Björn Töpel &lt;bjorn@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20250407180838.42877-10-andybnac@gmail.com
Signed-off-by: Alexandre Ghiti &lt;alexghiti@rivosinc.com&gt;
Signed-off-by: Palmer Dabbelt &lt;palmer@dabbelt.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild</title>
<updated>2025-04-05T22:46:50+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-04-05T22:46:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f4d2ef48250ad057e4f00087967b5ff366da9f39'/>
<id>f4d2ef48250ad057e4f00087967b5ff366da9f39</id>
<content type='text'>
Pull Kbuild updates from Masahiro Yamada:

 - Improve performance in gendwarfksyms

 - Remove deprecated EXTRA_*FLAGS and KBUILD_ENABLE_EXTRA_GCC_CHECKS

 - Support CONFIG_HEADERS_INSTALL for ARCH=um

 - Use more relative paths to sources files for better reproducibility

 - Support the loong64 Debian architecture

 - Add Kbuild bash completion

 - Introduce intermediate vmlinux.unstripped for architectures that need
   static relocations to be stripped from the final vmlinux

 - Fix versioning in Debian packages for -rc releases

 - Treat missing MODULE_DESCRIPTION() as an error

 - Convert Nios2 Makefiles to use the generic rule for built-in DTB

 - Add debuginfo support to the RPM package

* tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits)
  kbuild: rpm-pkg: build a debuginfo RPM
  kconfig: merge_config: use an empty file as initfile
  nios2: migrate to the generic rule for built-in DTB
  rust: kbuild: skip `--remap-path-prefix` for `rustdoc`
  kbuild: pacman-pkg: hardcode module installation path
  kbuild: deb-pkg: don't set KBUILD_BUILD_VERSION unconditionally
  modpost: require a MODULE_DESCRIPTION()
  kbuild: make all file references relative to source root
  x86: drop unnecessary prefix map configuration
  kbuild: deb-pkg: add comment about future removal of KDEB_COMPRESS
  kbuild: Add a help message for "headers"
  kbuild: deb-pkg: remove "version" variable in mkdebian
  kbuild: deb-pkg: fix versioning for -rc releases
  Documentation/kbuild: Fix indentation in modules.rst example
  x86: Get rid of Makefile.postlink
  kbuild: Create intermediate vmlinux build with relocations preserved
  kbuild: Introduce Kconfig symbol for linking vmlinux with relocations
  kbuild: link-vmlinux.sh: Make output file name configurable
  kbuild: do not generate .tmp_vmlinux*.map when CONFIG_VMLINUX_MAP=y
  Revert "kheaders: Ignore silly-rename files"
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull Kbuild updates from Masahiro Yamada:

 - Improve performance in gendwarfksyms

 - Remove deprecated EXTRA_*FLAGS and KBUILD_ENABLE_EXTRA_GCC_CHECKS

 - Support CONFIG_HEADERS_INSTALL for ARCH=um

 - Use more relative paths to sources files for better reproducibility

 - Support the loong64 Debian architecture

 - Add Kbuild bash completion

 - Introduce intermediate vmlinux.unstripped for architectures that need
   static relocations to be stripped from the final vmlinux

 - Fix versioning in Debian packages for -rc releases

 - Treat missing MODULE_DESCRIPTION() as an error

 - Convert Nios2 Makefiles to use the generic rule for built-in DTB

 - Add debuginfo support to the RPM package

* tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits)
  kbuild: rpm-pkg: build a debuginfo RPM
  kconfig: merge_config: use an empty file as initfile
  nios2: migrate to the generic rule for built-in DTB
  rust: kbuild: skip `--remap-path-prefix` for `rustdoc`
  kbuild: pacman-pkg: hardcode module installation path
  kbuild: deb-pkg: don't set KBUILD_BUILD_VERSION unconditionally
  modpost: require a MODULE_DESCRIPTION()
  kbuild: make all file references relative to source root
  x86: drop unnecessary prefix map configuration
  kbuild: deb-pkg: add comment about future removal of KDEB_COMPRESS
  kbuild: Add a help message for "headers"
  kbuild: deb-pkg: remove "version" variable in mkdebian
  kbuild: deb-pkg: fix versioning for -rc releases
  Documentation/kbuild: Fix indentation in modules.rst example
  x86: Get rid of Makefile.postlink
  kbuild: Create intermediate vmlinux build with relocations preserved
  kbuild: Introduce Kconfig symbol for linking vmlinux with relocations
  kbuild: link-vmlinux.sh: Make output file name configurable
  kbuild: do not generate .tmp_vmlinux*.map when CONFIG_VMLINUX_MAP=y
  Revert "kheaders: Ignore silly-rename files"
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: Remove duplicate CONFIG_PAGE_OFFSET definition</title>
<updated>2025-03-26T22:56:38+00:00</updated>
<author>
<name>Samuel Holland</name>
<email>samuel.holland@sifive.com</email>
</author>
<published>2024-10-26T17:13:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bffada8201fc9933ba0974b76b6068d6b4557ef4'/>
<id>bffada8201fc9933ba0974b76b6068d6b4557ef4</id>
<content type='text'>
This definition is already provided by include/generated/autoconf.h,
so it does not need to be provided on the command line.

Signed-off-by: Samuel Holland &lt;samuel.holland@sifive.com&gt;
Reviewed-by: Jesse Taube &lt;mr.bossman075@gmail.com&gt;
Link: https://lore.kernel.org/r/20241026171441.3047904-2-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This definition is already provided by include/generated/autoconf.h,
so it does not need to be provided on the command line.

Signed-off-by: Samuel Holland &lt;samuel.holland@sifive.com&gt;
Reviewed-by: Jesse Taube &lt;mr.bossman075@gmail.com&gt;
Link: https://lore.kernel.org/r/20241026171441.3047904-2-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
