linux.git/arch/riscv/kernel/pi, branch master

riscv: pi: use 'targets' instead of extra-y in Makefile

2025-09-18T14:20:56+00:00

%.pi.o files are built as prerequisites of other objects.
There is no need to use extra-y, which is planned for deprecation.

Signed-off-by: Masahiro Yamada 
Link: https://lore.kernel.org/r/20250602181023.528550-1-masahiroy@kernel.org
Signed-off-by: Paul Walmsley

riscv: mm: Use mmu-type from FDT to limit SATP mode

2025-09-18T14:18:14+00:00

Some RISC-V implementations may hang when attempting to write an
unsupported SATP mode, even though the latest RISC-V specification
states such writes should have no effect. To avoid this issue, the
logic for selecting SATP mode has been refined:

The kernel now determines the SATP mode limit by taking the minimum of
the value specified by the kernel command line (noXlvl) and the
"mmu-type" property in the device tree (FDT). If only one is specified,
use that.
- If the resulting limit is sv48 or higher, the kernel will probe SATP
  modes from this limit downward until a supported mode is found.
- If the limit is sv39, the kernel will directly use sv39 without
  probing.

This ensures SATP mode selection is safe and compatible with both
hardware and user configuration, minimizing the risk of hangs.

Signed-off-by: Junhui Liu 
Reviewed-by: Alexandre Ghiti 
Reviewed-by: Nutty Liu 
Link: https://lore.kernel.org/r/20250722-satp-from-fdt-v1-2-5ba22218fa5f@pigmoral.tech
Signed-off-by: Paul Walmsley

riscv: mm: Return intended SATP mode for noXlvl options

2025-09-17T23:00:59+00:00

Change the return value of match_noXlvl() to return the SATP mode that
will be used, rather than the mode being disabled. This enables unified
logic for return value judgement with the function that obtains mmu-type
from the fdt, avoiding extra conversion. This only changes the naming,
with no functional impact.

Signed-off-by: Junhui Liu 
Reviewed-by: Alexandre Ghiti 
Reviewed-by: Nutty Liu 
Link: https://lore.kernel.org/r/20250722-satp-from-fdt-v1-1-5ba22218fa5f@pigmoral.tech
Signed-off-by: Paul Walmsley

stackleak: Rename STACKLEAK to KSTACK_ERASE

2025-07-22T04:35:01+00:00

In preparation for adding Clang sanitizer coverage stack depth tracking
that can support stack depth callbacks:

- Add the new top-level CONFIG_KSTACK_ERASE option which will be
  implemented either with the stackleak GCC plugin, or with the Clang
  stack depth callback support.
- Rename CONFIG_GCC_PLUGIN_STACKLEAK as needed to CONFIG_KSTACK_ERASE,
  but keep it for anything specific to the GCC plugin itself.
- Rename all exposed "STACKLEAK" names and files to "KSTACK_ERASE" (named
  for what it does rather than what it protects against), but leave as
  many of the internals alone as possible to avoid even more churn.

While here, also split "prev_lowest_stack" into CONFIG_KSTACK_ERASE_METRICS,
since that's the only place it is referenced from.

Suggested-by: Ingo Molnar 
Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org
Signed-off-by: Kees Cook

riscv: Do not use fortify in early code

2024-10-25T13:18:36+00:00

Early code designates the code executed when the MMU is not yet enabled,
and this comes with some limitations (see
Documentation/arch/riscv/boot.rst, section "Pre-MMU execution").

FORTIFY_SOURCE must be disabled then since it can trigger kernel panics
as reported in [1].

Reported-by: Jason Montleon 
Closes: https://lore.kernel.org/linux-riscv/CAJD_bPJes4QhmXY5f63GHV9B9HFkSCoaZjk-qCT2NGS7Q9HODg@mail.gmail.com/ [1]
Fixes: a35707c3d850 ("riscv: add memory-type errata for T-Head")
Fixes: 26e7aacb83df ("riscv: Allow to downgrade paging mode from the command line")
Cc: stable@vger.kernel.org
Signed-off-by: Alexandre Ghiti 
Link: https://lore.kernel.org/r/20241009072749.45006-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt

RISC-V: Use Zkr to seed KASLR base address

2024-08-05T19:06:41+00:00

Parse the device tree for Zkr in the isa string.
If Zkr is present, use it to seed the kernel base address.

On an ACPI system, as of this commit, there is no easy way to check if
Zkr is present. Blindly running the instruction isn't an option as;
we have to be able to trust the firmware.

Signed-off-by: Jesse Taube 
Reviewed-by: Charlie Jenkins 
Reviewed-by: Alexandre Ghiti 
Tested-by: Zong Li 
Reviewed-by: Conor Dooley 
Link: https://lore.kernel.org/r/20240709173937.510084-5-jesse@rivosinc.com
Signed-off-by: Palmer Dabbelt

RISC-V: pi: Add kernel/pi/pi.h

2024-08-05T19:06:40+00:00

Add pi.h header for declarations of the kernel/pi prefixed functions
and any other related declarations.

Suggested-by: Charlie Jenkins 
Signed-off-by: Jesse Taube 
Reviewed-by: Alexandre Ghiti 
Link: https://lore.kernel.org/r/20240709173937.510084-4-jesse@rivosinc.com
Signed-off-by: Palmer Dabbelt

RISC-V: pi: Force hidden visibility for all symbol references

2024-08-05T19:06:38+00:00

Eliminate all GOT entries in the .pi section, by forcing hidden
visibility for all symbol references, which informs the compiler that
such references will be resolved at link time without the need for
allocating GOT entries.

Include linux/hidden.h in Makefile, like arm64, for the
hidden visibility attribute.

Signed-off-by: Jesse Taube 
Reviewed-by: Alexandre Ghiti 
Link: https://lore.kernel.org/r/20240709173937.510084-2-jesse@rivosinc.com
Signed-off-by: Palmer Dabbelt

Makefile: remove redundant tool coverage variables

2024-05-14T14:35:48+00:00

Now Kbuild provides reasonable defaults for objtool, sanitizers, and
profilers.

Remove redundant variables.

Note:

This commit changes the coverage for some objects:

  - include arch/mips/vdso/vdso-image.o into UBSAN, GCOV, KCOV
  - include arch/sparc/vdso/vdso-image-*.o into UBSAN
  - include arch/sparc/vdso/vma.o into UBSAN
  - include arch/x86/entry/vdso/extable.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
  - include arch/x86/entry/vdso/vdso-image-*.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
  - include arch/x86/entry/vdso/vdso32-setup.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
  - include arch/x86/entry/vdso/vma.o into GCOV, KCOV
  - include arch/x86/um/vdso/vma.o into KASAN, GCOV, KCOV

I believe these are positive effects because all of them are kernel
space objects.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Kees Cook 
Tested-by: Roberto Sassu

RISC-V: build: Allow LTO to be selected

2024-01-22T18:06:29+00:00

Allow LTO to be selected for RISC-V, only when LLD >= 14, since there is
an issue [1] in prior LLD versions that prevents LLD to generate proper
machine code for RISC-V when writing `nop`s.

To avoid boot failures in QEMU [2], '-mattr=+c' and '-mattr=+relax'
need to be passed via '-mllvm' to ld.lld, as there appears to be an
issue with LLVM's target-features and LTO [3], which can result in
incorrect relocations to branch targets [4]. Once this is fixed in LLVM,
it can be made conditional on affected ld.lld versions.

Disable LTO for arch/riscv/kernel/pi, as llvm-objcopy expects an ELF
object file when manipulating the files in that subfolder, rather than
LLVM bitcode.

[1] https://github.com/llvm/llvm-project/issues/50505, resolved by LLVM
    commit e63455d5e0e5 ("[MC] Use local MCSubtargetInfo in writeNops")
[2] https://github.com/ClangBuiltLinux/linux/issues/1942
[3] https://github.com/llvm/llvm-project/issues/59350
[4] https://github.com/llvm/llvm-project/issues/65090

Tested-by: Wende Tan 
Signed-off-by: Wende Tan 
Co-developed-by: Nathan Chancellor 
Signed-off-by: Nathan Chancellor 
Reviewed-by: Conor Dooley 
Link: https://lore.kernel.org/r/20231017-riscv-lto-v4-1-e7810b24e805@kernel.org
Signed-off-by: Palmer Dabbelt