<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/riscv/kernel/cacheinfo.c, branch v6.16</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>riscv: cacheinfo: Use of_property_present() for non-boolean properties</title>
<updated>2025-02-14T21:04:20+00:00</updated>
<author>
<name>Rob Herring</name>
<email>robh@kernel.org</email>
</author>
<published>2024-11-04T19:03:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=fb8179ce2996bffaa36a04e2b6262843b01b7565'/>
<id>fb8179ce2996bffaa36a04e2b6262843b01b7565</id>
<content type='text'>
The use of of_property_read_bool() for non-boolean properties is
deprecated in favor of of_property_present() when testing for property
presence.

Signed-off-by: Rob Herring (Arm) &lt;robh@kernel.org&gt;
Reviewed-by: Clément Léger &lt;cleger@rivosinc.com&gt;
Cc: stable@vger.kernel.org
Fixes: 76d2a0493a17 ("RISC-V: Init and Halt Code")
Link: https://lore.kernel.org/r/20241104190314.270095-1-robh@kernel.org
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The use of of_property_read_bool() for non-boolean properties is
deprecated in favor of of_property_present() when testing for property
presence.

Signed-off-by: Rob Herring (Arm) &lt;robh@kernel.org&gt;
Reviewed-by: Clément Léger &lt;cleger@rivosinc.com&gt;
Cc: stable@vger.kernel.org
Fixes: 76d2a0493a17 ("RISC-V: Init and Halt Code")
Link: https://lore.kernel.org/r/20241104190314.270095-1-robh@kernel.org
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: Prevent a bad reference count on CPU nodes</title>
<updated>2024-10-25T13:18:39+00:00</updated>
<author>
<name>Miquel Sabaté Solà</name>
<email>mikisabate@gmail.com</email>
</author>
<published>2024-09-13T08:00:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=37233169a6ea912020c572f870075a63293b786a'/>
<id>37233169a6ea912020c572f870075a63293b786a</id>
<content type='text'>
When populating cache leaves we previously fetched the CPU device node
at the very beginning. But when ACPI is enabled we go through a
specific branch which returns early and does not call 'of_node_put' for
the node that was acquired.

Since we are not using a CPU device node for the ACPI code anyways, we
can simply move the initialization of it just passed the ACPI block, and
we are guaranteed to have an 'of_node_put' call for the acquired node.
This prevents a bad reference count of the CPU device node.

Moreover, the previous function did not check for errors when acquiring
the device node, so a return -ENOENT has been added for that case.

Signed-off-by: Miquel Sabaté Solà &lt;mikisabate@gmail.com&gt;
Reviewed-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Reviewed-by: Sunil V L &lt;sunilvl@ventanamicro.com&gt;
Reviewed-by: Alexandre Ghiti &lt;alexghiti@rivosinc.com&gt;
Fixes: 604f32ea6909 ("riscv: cacheinfo: initialize cacheinfo's level and  type from ACPI PPTT")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240913080053.36636-1-mikisabate@gmail.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When populating cache leaves we previously fetched the CPU device node
at the very beginning. But when ACPI is enabled we go through a
specific branch which returns early and does not call 'of_node_put' for
the node that was acquired.

Since we are not using a CPU device node for the ACPI code anyways, we
can simply move the initialization of it just passed the ACPI block, and
we are guaranteed to have an 'of_node_put' call for the acquired node.
This prevents a bad reference count of the CPU device node.

Moreover, the previous function did not check for errors when acquiring
the device node, so a return -ENOENT has been added for that case.

Signed-off-by: Miquel Sabaté Solà &lt;mikisabate@gmail.com&gt;
Reviewed-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Reviewed-by: Sunil V L &lt;sunilvl@ventanamicro.com&gt;
Reviewed-by: Alexandre Ghiti &lt;alexghiti@rivosinc.com&gt;
Fixes: 604f32ea6909 ("riscv: cacheinfo: initialize cacheinfo's level and  type from ACPI PPTT")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240913080053.36636-1-mikisabate@gmail.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: cacheinfo: Add back init_cache_level() function</title>
<updated>2024-09-16T03:15:50+00:00</updated>
<author>
<name>Steffen Persvold</name>
<email>spersvold@gmail.com</email>
</author>
<published>2024-07-07T00:35:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1845d381f28063a3b68e9e148d5a7f01d6be8721'/>
<id>1845d381f28063a3b68e9e148d5a7f01d6be8721</id>
<content type='text'>
commit 5944ce092b97 (arch_topology: Build cacheinfo from primary CPU)
removed the init_cache_level() function from arch/riscv/kernel/cacheinfo.c
and relies on the init_cpu_topology() function in drivers/base/arch_topology.c
to call fetch_cache_info() which in turn calls init_of_cache_level() to
populate the cache hierarchy information. However, init_cpu_topology() is only
called from smpboot.c:smp_prepare_cpus() and thus only available when
CONFIG_SMP is defined.

To support non-SMP enabled kernels to still detect cache hierarchy, we add back
the init_cache_level() function. The init_level_allocate_ci() function handles
this gracefully on SMP-enabled kernels anyway where fetch_cache_info() is
called from init_cpu_topology() earlier in the boot phase.

Signed-off-by: Steffen Persvold &lt;spersvold@gmail.com&gt;
Link: https://lore.kernel.org/r/20240707003515.5058-1-spersvold@gmail.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 5944ce092b97 (arch_topology: Build cacheinfo from primary CPU)
removed the init_cache_level() function from arch/riscv/kernel/cacheinfo.c
and relies on the init_cpu_topology() function in drivers/base/arch_topology.c
to call fetch_cache_info() which in turn calls init_of_cache_level() to
populate the cache hierarchy information. However, init_cpu_topology() is only
called from smpboot.c:smp_prepare_cpus() and thus only available when
CONFIG_SMP is defined.

To support non-SMP enabled kernels to still detect cache hierarchy, we add back
the init_cache_level() function. The init_level_allocate_ci() function handles
this gracefully on SMP-enabled kernels anyway where fetch_cache_info() is
called from init_cpu_topology() earlier in the boot phase.

Signed-off-by: Steffen Persvold &lt;spersvold@gmail.com&gt;
Link: https://lore.kernel.org/r/20240707003515.5058-1-spersvold@gmail.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: cacheinfo: initialize cacheinfo's level and type from ACPI PPTT</title>
<updated>2024-07-24T14:39:36+00:00</updated>
<author>
<name>Yunhui Cui</name>
<email>cuiyunhui@bytedance.com</email>
</author>
<published>2024-06-17T13:14:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=604f32ea6909b0ebb8ab0bf1ab7dc66ee3dc8955'/>
<id>604f32ea6909b0ebb8ab0bf1ab7dc66ee3dc8955</id>
<content type='text'>
Before cacheinfo can be built correctly, we need to initialize level
and type. Since RISC-V currently does not have a register group that
describes cache-related attributes like ARM64, we cannot obtain them
directly, so now we obtain cache leaves from the ACPI PPTT table
(acpi_get_cache_info()) and set the cache type through split_levels.

Suggested-by: Jeremy Linton &lt;jeremy.linton@arm.com&gt;
Suggested-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Reviewed-by: Conor Dooley &lt;conor.dooley@microchip.com&gt;
Reviewed-by: Sunil V L &lt;sunilvl@ventanamicro.com&gt;
Reviewed-by: Jeremy Linton &lt;jeremy.linton@arm.com&gt;
Reviewed-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Signed-off-by: Yunhui Cui &lt;cuiyunhui@bytedance.com&gt;
Link: https://lore.kernel.org/r/20240617131425.7526-2-cuiyunhui@bytedance.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Before cacheinfo can be built correctly, we need to initialize level
and type. Since RISC-V currently does not have a register group that
describes cache-related attributes like ARM64, we cannot obtain them
directly, so now we obtain cache leaves from the ACPI PPTT table
(acpi_get_cache_info()) and set the cache type through split_levels.

Suggested-by: Jeremy Linton &lt;jeremy.linton@arm.com&gt;
Suggested-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Reviewed-by: Conor Dooley &lt;conor.dooley@microchip.com&gt;
Reviewed-by: Sunil V L &lt;sunilvl@ventanamicro.com&gt;
Reviewed-by: Jeremy Linton &lt;jeremy.linton@arm.com&gt;
Reviewed-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Signed-off-by: Yunhui Cui &lt;cuiyunhui@bytedance.com&gt;
Link: https://lore.kernel.org/r/20240617131425.7526-2-cuiyunhui@bytedance.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: cacheinfo: remove the useless input parameter (node) of ci_leaf_init()</title>
<updated>2024-07-24T14:39:35+00:00</updated>
<author>
<name>Yunhui Cui</name>
<email>cuiyunhui@bytedance.com</email>
</author>
<published>2024-06-17T13:14:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ee3fab10cb1566562aa683f319066eaeecccf918'/>
<id>ee3fab10cb1566562aa683f319066eaeecccf918</id>
<content type='text'>
ci_leaf_init() is a declared static function. The implementation of the
function body and the caller do not use the parameter (struct device_node
*node) input parameter, so remove it.

Fixes: 6a24915145c9 ("Revert "riscv: Set more data to cacheinfo"")
Signed-off-by: Yunhui Cui &lt;cuiyunhui@bytedance.com&gt;
Reviewed-by: Jeremy Linton &lt;jeremy.linton@arm.com&gt;
Reviewed-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Link: https://lore.kernel.org/r/20240617131425.7526-1-cuiyunhui@bytedance.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
ci_leaf_init() is a declared static function. The implementation of the
function body and the caller do not use the parameter (struct device_node
*node) input parameter, so remove it.

Fixes: 6a24915145c9 ("Revert "riscv: Set more data to cacheinfo"")
Signed-off-by: Yunhui Cui &lt;cuiyunhui@bytedance.com&gt;
Reviewed-by: Jeremy Linton &lt;jeremy.linton@arm.com&gt;
Reviewed-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Link: https://lore.kernel.org/r/20240617131425.7526-1-cuiyunhui@bytedance.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'riscv-for-linus-6.4-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux</title>
<updated>2023-04-28T23:55:39+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-04-28T23:55:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=89d77f71f493a3663b10fa812d17f472935d24be'/>
<id>89d77f71f493a3663b10fa812d17f472935d24be</id>
<content type='text'>
Pull RISC-V updates from Palmer Dabbelt:

 - Support for runtime detection of the Svnapot extension

 - Support for Zicboz when clearing pages

 - We've moved to GENERIC_ENTRY

 - Support for !MMU on rv32 systems

 - The linear region is now mapped via huge pages

 - Support for building relocatable kernels

 - Support for the hwprobe interface

 - Various fixes and cleanups throughout the tree

* tag 'riscv-for-linus-6.4-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (57 commits)
  RISC-V: hwprobe: Explicity check for -1 in vdso init
  RISC-V: hwprobe: There can only be one first
  riscv: Allow to downgrade paging mode from the command line
  dt-bindings: riscv: add sv57 mmu-type
  RISC-V: hwprobe: Remove __init on probe_vendor_features()
  riscv: Use --emit-relocs in order to move .rela.dyn in init
  riscv: Check relocations at compile time
  powerpc: Move script to check relocations at compile time in scripts/
  riscv: Introduce CONFIG_RELOCATABLE
  riscv: Move .rela.dyn outside of init to avoid empty relocations
  riscv: Prepare EFI header for relocatable kernels
  riscv: Unconditionnally select KASAN_VMALLOC if KASAN
  riscv: Fix ptdump when KASAN is enabled
  riscv: Fix EFI stub usage of KASAN instrumented strcmp function
  riscv: Move DTB_EARLY_BASE_VA to the kernel address space
  riscv: Rework kasan population functions
  riscv: Split early and final KASAN population functions
  riscv: Use PUD/P4D/PGD pages for the linear mapping
  riscv: Move the linear mapping creation in its own function
  riscv: Get rid of riscv_pfn_base variable
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull RISC-V updates from Palmer Dabbelt:

 - Support for runtime detection of the Svnapot extension

 - Support for Zicboz when clearing pages

 - We've moved to GENERIC_ENTRY

 - Support for !MMU on rv32 systems

 - The linear region is now mapped via huge pages

 - Support for building relocatable kernels

 - Support for the hwprobe interface

 - Various fixes and cleanups throughout the tree

* tag 'riscv-for-linus-6.4-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (57 commits)
  RISC-V: hwprobe: Explicity check for -1 in vdso init
  RISC-V: hwprobe: There can only be one first
  riscv: Allow to downgrade paging mode from the command line
  dt-bindings: riscv: add sv57 mmu-type
  RISC-V: hwprobe: Remove __init on probe_vendor_features()
  riscv: Use --emit-relocs in order to move .rela.dyn in init
  riscv: Check relocations at compile time
  powerpc: Move script to check relocations at compile time in scripts/
  riscv: Introduce CONFIG_RELOCATABLE
  riscv: Move .rela.dyn outside of init to avoid empty relocations
  riscv: Prepare EFI header for relocatable kernels
  riscv: Unconditionnally select KASAN_VMALLOC if KASAN
  riscv: Fix ptdump when KASAN is enabled
  riscv: Fix EFI stub usage of KASAN instrumented strcmp function
  riscv: Move DTB_EARLY_BASE_VA to the kernel address space
  riscv: Rework kasan population functions
  riscv: Split early and final KASAN population functions
  riscv: Use PUD/P4D/PGD pages for the linear mapping
  riscv: Move the linear mapping creation in its own function
  riscv: Get rid of riscv_pfn_base variable
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>riscv: cacheinfo: Adjust includes to remove of_device.h</title>
<updated>2023-04-13T22:46:34+00:00</updated>
<author>
<name>Rob Herring</name>
<email>robh@kernel.org</email>
</author>
<published>2023-03-29T15:52:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=06d90669769b6fc0a390b2f724457994d247aaae'/>
<id>06d90669769b6fc0a390b2f724457994d247aaae</id>
<content type='text'>
Now that of_cpu_device_node_get() is defined in of.h, of_device.h is just
implicitly including other includes, and is no longer needed. Adjust the
include files with what was implicitly included by of_device.h (cpu.h and
of.h) and drop including of_device.h.

Link: https://lore.kernel.org/r/20230329-dt-cpu-header-cleanups-v1-9-581e2605fe47@kernel.org
Signed-off-by: Rob Herring &lt;robh@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Now that of_cpu_device_node_get() is defined in of.h, of_device.h is just
implicitly including other includes, and is no longer needed. Adjust the
include files with what was implicitly included by of_device.h (cpu.h and
of.h) and drop including of_device.h.

Link: https://lore.kernel.org/r/20230329-dt-cpu-header-cleanups-v1-9-581e2605fe47@kernel.org
Signed-off-by: Rob Herring &lt;robh@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "riscv: Set more data to cacheinfo"</title>
<updated>2023-04-11T23:07:53+00:00</updated>
<author>
<name>Song Shuai</name>
<email>suagrfillet@gmail.com</email>
</author>
<published>2023-03-08T06:47:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6a24915145c922b79d3ac78f681137a4c14a6d6b'/>
<id>6a24915145c922b79d3ac78f681137a4c14a6d6b</id>
<content type='text'>
This reverts commit baf7cbd94b5688f167443a2cc3dcea3300132099.

There are some duplicate cache attributes populations executed
in both ci_leaf_init() and later cache_setup_properties().

Revert the commit baf7cbd94b56 ("riscv: Set more data to cacheinfo")
to setup only the level and type attributes at this early place.

Signed-off-by: Song Shuai &lt;suagrfillet@gmail.com&gt;
Acked-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Acked-by: Conor Dooley &lt;conor.dooley@microchip.com&gt;
Link: https://lore.kernel.org/r/20230308064734.512457-1-suagrfillet@gmail.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 reverts commit baf7cbd94b5688f167443a2cc3dcea3300132099.

There are some duplicate cache attributes populations executed
in both ci_leaf_init() and later cache_setup_properties().

Revert the commit baf7cbd94b56 ("riscv: Set more data to cacheinfo")
to setup only the level and type attributes at this early place.

Signed-off-by: Song Shuai &lt;suagrfillet@gmail.com&gt;
Acked-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Acked-by: Conor Dooley &lt;conor.dooley@microchip.com&gt;
Link: https://lore.kernel.org/r/20230308064734.512457-1-suagrfillet@gmail.com
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arch_topology: Build cacheinfo from primary CPU</title>
<updated>2023-01-18T09:58:40+00:00</updated>
<author>
<name>Pierre Gondois</name>
<email>pierre.gondois@arm.com</email>
</author>
<published>2023-01-04T18:30:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5944ce092b97caed5d86d961e963b883b5c44ee2'/>
<id>5944ce092b97caed5d86d961e963b883b5c44ee2</id>
<content type='text'>
commit 3fcbf1c77d08 ("arch_topology: Fix cache attributes detection
in the CPU hotplug path")
adds a call to detect_cache_attributes() to populate the cacheinfo
before updating the siblings mask. detect_cache_attributes() allocates
memory and can take the PPTT mutex (on ACPI platforms). On PREEMPT_RT
kernels, on secondary CPUs, this triggers a:
  'BUG: sleeping function called from invalid context' [1]
as the code is executed with preemption and interrupts disabled.

The primary CPU was previously storing the cache information using
the now removed (struct cpu_topology).llc_id:
commit 5b8dc787ce4a ("arch_topology: Drop LLC identifier stash from
the CPU topology")

allocate_cache_info() tries to build the cacheinfo from the primary
CPU prior secondary CPUs boot, if the DT/ACPI description
contains cache information.
If allocate_cache_info() fails, then fallback to the current state
for the cacheinfo allocation. [1] will be triggered in such case.

When unplugging a CPU, the cacheinfo memory cannot be freed. If it
was, then the memory would be allocated early by the re-plugged
CPU and would trigger [1].

Note that populate_cache_leaves() might be called multiple times
due to populate_leaves being moved up. This is required since
detect_cache_attributes() might be called with per_cpu_cacheinfo(cpu)
being allocated but not populated.

[1]:
 | BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
 | in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111
 | preempt_count: 1, expected: 0
 | RCU nest depth: 1, expected: 1
 | 3 locks held by swapper/111/0:
 |  #0:  (&amp;pcp-&gt;lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8
 |  #1:  (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0
 |  #2:  (&amp;zone-&gt;lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80
 | irq event stamp: 0
 | hardirqs last  enabled at (0):  0x0
 | hardirqs last disabled at (0):  copy_process+0x5dc/0x1ab8
 | softirqs last  enabled at (0):  copy_process+0x5dc/0x1ab8
 | softirqs last disabled at (0):  0x0
 | Preemption disabled at:
 |  migrate_enable+0x30/0x130
 | CPU: 111 PID: 0 Comm: swapper/111 Tainted: G        W          6.0.0-rc4-rt6-[...]
 | Call trace:
 |  __kmalloc+0xbc/0x1e8
 |  detect_cache_attributes+0x2d4/0x5f0
 |  update_siblings_masks+0x30/0x368
 |  store_cpu_topology+0x78/0xb8
 |  secondary_start_kernel+0xd0/0x198
 |  __secondary_switched+0xb0/0xb4

Signed-off-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Acked-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20230104183033.755668-7-pierre.gondois@arm.com
Signed-off-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 3fcbf1c77d08 ("arch_topology: Fix cache attributes detection
in the CPU hotplug path")
adds a call to detect_cache_attributes() to populate the cacheinfo
before updating the siblings mask. detect_cache_attributes() allocates
memory and can take the PPTT mutex (on ACPI platforms). On PREEMPT_RT
kernels, on secondary CPUs, this triggers a:
  'BUG: sleeping function called from invalid context' [1]
as the code is executed with preemption and interrupts disabled.

The primary CPU was previously storing the cache information using
the now removed (struct cpu_topology).llc_id:
commit 5b8dc787ce4a ("arch_topology: Drop LLC identifier stash from
the CPU topology")

allocate_cache_info() tries to build the cacheinfo from the primary
CPU prior secondary CPUs boot, if the DT/ACPI description
contains cache information.
If allocate_cache_info() fails, then fallback to the current state
for the cacheinfo allocation. [1] will be triggered in such case.

When unplugging a CPU, the cacheinfo memory cannot be freed. If it
was, then the memory would be allocated early by the re-plugged
CPU and would trigger [1].

Note that populate_cache_leaves() might be called multiple times
due to populate_leaves being moved up. This is required since
detect_cache_attributes() might be called with per_cpu_cacheinfo(cpu)
being allocated but not populated.

[1]:
 | BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
 | in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111
 | preempt_count: 1, expected: 0
 | RCU nest depth: 1, expected: 1
 | 3 locks held by swapper/111/0:
 |  #0:  (&amp;pcp-&gt;lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8
 |  #1:  (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0
 |  #2:  (&amp;zone-&gt;lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80
 | irq event stamp: 0
 | hardirqs last  enabled at (0):  0x0
 | hardirqs last disabled at (0):  copy_process+0x5dc/0x1ab8
 | softirqs last  enabled at (0):  copy_process+0x5dc/0x1ab8
 | softirqs last disabled at (0):  0x0
 | Preemption disabled at:
 |  migrate_enable+0x30/0x130
 | CPU: 111 PID: 0 Comm: swapper/111 Tainted: G        W          6.0.0-rc4-rt6-[...]
 | Call trace:
 |  __kmalloc+0xbc/0x1e8
 |  detect_cache_attributes+0x2d4/0x5f0
 |  update_siblings_masks+0x30/0x368
 |  store_cpu_topology+0x78/0xb8
 |  secondary_start_kernel+0xd0/0x198
 |  __secondary_switched+0xb0/0xb4

Signed-off-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
Acked-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20230104183033.755668-7-pierre.gondois@arm.com
Signed-off-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cacheinfo: Use RISC-V's init_cache_level() as generic OF implementation</title>
<updated>2023-01-17T21:59:52+00:00</updated>
<author>
<name>Pierre Gondois</name>
<email>pierre.gondois@arm.com</email>
</author>
<published>2023-01-04T18:30:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c3719bd9eeb2edf84bd263d662e36ca0ba262a23'/>
<id>c3719bd9eeb2edf84bd263d662e36ca0ba262a23</id>
<content type='text'>
RISC-V's implementation of init_of_cache_level() is following
the Devicetree Specification v0.3 regarding caches, cf.:
- s3.7.3 'Internal (L1) Cache Properties'
- s3.8 'Multi-level and Shared Cache Nodes'

Allow reusing the implementation by moving it.

Also make 'levels', 'leaves' and 'level' unsigned int.

Signed-off-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Conor Dooley &lt;conor.dooley@microchip.com&gt;
Acked-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20230104183033.755668-2-pierre.gondois@arm.com
Signed-off-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
RISC-V's implementation of init_of_cache_level() is following
the Devicetree Specification v0.3 regarding caches, cf.:
- s3.7.3 'Internal (L1) Cache Properties'
- s3.8 'Multi-level and Shared Cache Nodes'

Allow reusing the implementation by moving it.

Also make 'levels', 'leaves' and 'level' unsigned int.

Signed-off-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Conor Dooley &lt;conor.dooley@microchip.com&gt;
Acked-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
Link: https://lore.kernel.org/r/20230104183033.755668-2-pierre.gondois@arm.com
Signed-off-by: Sudeep Holla &lt;sudeep.holla@arm.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
