linux.git/arch/riscv/kernel/cpu.c, branch v6.12

riscv: Add vendor extensions to /proc/cpuinfo

2024-07-22T22:36:55+00:00

All of the supported vendor extensions that have been listed in
riscv_isa_vendor_ext_list can be exported through /proc/cpuinfo.

Signed-off-by: Charlie Jenkins 
Reviewed-by: Evan Green 
Reviewed-by: Conor Dooley 
Link: https://lore.kernel.org/r/20240719-support_vendor_extensions-v3-2-0af7587bbec0@rivosinc.com
Signed-off-by: Palmer Dabbelt

riscv: cpufeature: Fix thead vector hwcap removal

2024-05-22T16:41:02+00:00

The riscv_cpuinfo struct that contains mvendorid and marchid is not
populated until all harts are booted which happens after the DT parsing.
Use the mvendorid/marchid from the boot hart to determine if the DT
contains an invalid V.

Fixes: d82f32202e0d ("RISC-V: Ignore V from the riscv,isa DT property on older T-Head CPUs")
Signed-off-by: Charlie Jenkins 
Reviewed-by: Conor Dooley 
Reviewed-by: Guo Ren 
Link: https://lore.kernel.org/r/20240502-cpufeature_fixes-v4-1-b3d1a088722d@rivosinc.com
Signed-off-by: Palmer Dabbelt

Merge patch series "Linux RISC-V AIA Preparatory Series"

2023-11-09T02:57:17+00:00

These two  ended up in the AIA series, but they're really independent
improvements.

* b4-shazam-merge:
  of: property: Add fw_devlink support for msi-parent
  RISC-V: Don't fail in riscv_of_parent_hartid() for disabled HARTs

Link: https://lore.kernel.org/r/20231027154254.355853-1-apatel@ventanamicro.com
Signed-off-by: Palmer Dabbelt

RISC-V: Don't fail in riscv_of_parent_hartid() for disabled HARTs

2023-11-09T02:57:14+00:00

The riscv_of_processor_hartid() used by riscv_of_parent_hartid() fails
for HARTs disabled in the DT. This results in the following warning
thrown by the RISC-V INTC driver for the E-core on SiFive boards:

[    0.000000] riscv-intc: unable to find hart id for /cpus/cpu@0/interrupt-controller

The riscv_of_parent_hartid() is only expected to read the hartid
from the DT so we directly call of_get_cpu_hwid() instead of calling
riscv_of_processor_hartid().

Fixes: ad635e723e17 ("riscv: cpu: Add 64bit hartid support on RV64")
Signed-off-by: Anup Patel 
Reviewed-by: Atish Patra 
Link: https://lore.kernel.org/r/20231027154254.355853-2-apatel@ventanamicro.com
Signed-off-by: Palmer Dabbelt

RISC-V: Show accurate per-hart isa in /proc/cpuinfo

2023-11-07T23:13:09+00:00

In /proc/cpuinfo, most of the information we show for each processor is
specific to that hart: marchid, mvendorid, mimpid, processor, hart,
compatible, and the mmu size. But the ISA string gets filtered through a
lowest common denominator mask, so that if one CPU is missing an ISA
extension, no CPUs will show it.

Now that we track the ISA extensions for each hart, let's report ISA
extension info accurately per-hart in /proc/cpuinfo. We cannot change
the "isa:" line, as usermode may be relying on that line to show only
the common set of extensions supported across all harts. Add a new "hart
isa" line instead, which reports the true set of extensions for that
hart.

Signed-off-by: Evan Green 
Reviewed-by: Andrew Jones 
Reviewed-by: Conor Dooley 
Link: https://lore.kernel.org/r/20231106232439.3176268-1-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt

Merge tag 'riscv-for-linus-6.6-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2023-09-01T15:09:48+00:00

Pull RISC-V updates from Palmer Dabbelt:

 - Support for the new "riscv,isa-extensions" and "riscv,isa-base"
   device tree interfaces for probing extensions

 - Support for userspace access to the performance counters

 - Support for more instructions in kprobes

 - Crash kernels can be allocated above 4GiB

 - Support for KCFI

 - Support for ELFs in !MMU configurations

 - ARCH_KMALLOC_MINALIGN has been reduced to 8

 - mmap() defaults to sv48-sized addresses, with longer addresses hidden
   behind a hint (similar to Arm and Intel)

 - Also various fixes and cleanups

* tag 'riscv-for-linus-6.6-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (51 commits)
  lib/Kconfig.debug: Restrict DEBUG_INFO_SPLIT for RISC-V
  riscv: support PREEMPT_DYNAMIC with static keys
  riscv: Move create_tmp_mapping() to init sections
  riscv: Mark KASAN tmp* page tables variables as static
  riscv: mm: use bitmap_zero() API
  riscv: enable DEBUG_FORCE_FUNCTION_ALIGN_64B
  riscv: remove redundant mv instructions
  RISC-V: mm: Document mmap changes
  RISC-V: mm: Update pgtable comment documentation
  RISC-V: mm: Add tests for RISC-V mm
  RISC-V: mm: Restrict address space for sv39,sv48,sv57
  riscv: enable DMA_BOUNCE_UNALIGNED_KMALLOC for !dma_coherent
  riscv: allow kmalloc() caches aligned to the smallest value
  riscv: support the elf-fdpic binfmt loader
  binfmt_elf_fdpic: support 64-bit systems
  riscv: Allow CONFIG_CFI_CLANG to be selected
  riscv/purgatory: Disable CFI
  riscv: Add CFI error handling
  riscv: Add ftrace_stub_graph
  riscv: Add types to indirectly called assembly functions
  ...

riscv: Fix CPU feature detection with SMP disabled

2023-08-08T22:28:25+00:00

commit 914d6f44fc50 ("RISC-V: only iterate over possible CPUs in ISA
string parser") changed riscv_fill_hwcap() from iterating over CPU DT
nodes to iterating over logical CPU IDs. Since this function runs long
before cpu_dev_init() creates CPU devices, it hits the fallback path in
of_cpu_device_node_get(), which itself iterates over the DT nodes,
searching for a node with the requested CPU ID. (Incidentally, this
makes riscv_fill_hwcap() now take quadratic time.)

riscv_fill_hwcap() passes a logical CPU ID to of_cpu_device_node_get(),
which uses the arch_match_cpu_phys_id() hook to translate the logical ID
to a physical ID as found in the DT.

arch_match_cpu_phys_id() has a generic weak definition, and RISC-V
provides a strong definition using cpuid_to_hartid_map(). However, the
RISC-V specific implementation is located in arch/riscv/kernel/smp.c,
and that file is only compiled when SMP is enabled.

As a result, when SMP is disabled, the generic definition is used, and
riscv_isa gets initialized based on the ISA string of hart 0, not the
boot hart. On FU740, this means has_fpu() returns false, and userspace
crashes when trying to use floating-point instructions.

Fix this by moving arch_match_cpu_phys_id() to a file which is always
compiled.

Fixes: 70114560b285 ("RISC-V: Add RISC-V specific arch_match_cpu_phys_id")
Fixes: 914d6f44fc50 ("RISC-V: only iterate over possible CPUs in ISA string parser")
Reported-by: Palmer Dabbelt 
Signed-off-by: Samuel Holland 
Reviewed-by: Conor Dooley 
Link: https://lore.kernel.org/r/20230803012608.3540081-1-samuel.holland@sifive.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt

RISC-V: cpu: refactor deprecated strncpy

2023-08-02T20:45:28+00:00

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

Favor not copying strings onto stack and instead use strings directly.
This avoids hard-coding sizes and buffer lengths all together.

Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Suggested-by: Kees Cook 
Signed-off-by: Justin Stitt 
Reviewed-by: Palmer Dabbelt 
Acked-by: Palmer Dabbelt 
Reviewed-by: Kees Cook 
Reviewed-by: Conor Dooley 
Link: https://lore.kernel.org/r/20230802-arch-riscv-kernel-v2-1-24266e85bc96@google.com
Signed-off-by: Palmer Dabbelt

RISC-V: provide Kconfig & commandline options to control parsing "riscv,isa"

2023-07-25T23:26:25+00:00

As it says on the tin, provide Kconfig option to control parsing the
"riscv,isa" devicetree property. If either option is used, the kernel
will fall back to parsing "riscv,isa", where "riscv,isa-base" and
"riscv,isa-extensions" are not present.
The Kconfig options are set up so that the default kernel configuration
will enable the fallback path, without needing the commandline option.

Suggested-by: Andrew Jones 
Suggested-by: Palmer Dabbelt 
Reviewed-by: Andrew Jones 
Signed-off-by: Conor Dooley 
Link: https://lore.kernel.org/r/20230713-aviator-plausibly-a35662485c2c@wendy
Signed-off-by: Palmer Dabbelt

RISC-V: try new extension properties in of_early_processor_hartid()

2023-07-25T23:26:24+00:00

To fully deprecate the kernel's use of "riscv,isa",
of_early_processor_hartid() needs to first try using the new properties,
before falling back to "riscv,isa".

Reviewed-by: Andrew Jones 
Signed-off-by: Conor Dooley 
Link: https://lore.kernel.org/r/20230713-tablet-jimmy-987fea0eb2e1@wendy
Signed-off-by: Palmer Dabbelt