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2024-10-25riscv: Do not use fortify in early codeAlexandre Ghiti
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 <jmontleo@redhat.com> 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 <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20241009072749.45006-1-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-08-05RISC-V: Use Zkr to seed KASLR base addressJesse Taube
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 <jesse@rivosinc.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Tested-by: Zong Li <zong.li@sifive.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20240709173937.510084-5-jesse@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-08-05RISC-V: pi: Add kernel/pi/pi.hJesse Taube
Add pi.h header for declarations of the kernel/pi prefixed functions and any other related declarations. Suggested-by: Charlie Jenkins <charlie@rivosinc.com> Signed-off-by: Jesse Taube <jesse@rivosinc.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240709173937.510084-4-jesse@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-08-05RISC-V: pi: Force hidden visibility for all symbol referencesJesse Taube
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 <jesse@rivosinc.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240709173937.510084-2-jesse@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-05-14Makefile: remove redundant tool coverage variablesMasahiro Yamada
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 <masahiroy@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Roberto Sassu <roberto.sassu@huawei.com>
2024-01-22RISC-V: build: Allow LTO to be selectedWende Tan
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 <twd2.me@gmail.com> Signed-off-by: Wende Tan <twd2.me@gmail.com> Co-developed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20231017-riscv-lto-v4-1-e7810b24e805@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-11riscv: Fix an off-by-one in get_early_cmdline()Christophe JAILLET
The ending NULL is not taken into account by strncat(), so switch to strlcat() to correctly compute the size of the available memory when appending CONFIG_CMDLINE to 'early_cmdline'. Fixes: 26e7aacb83df ("riscv: Allow to downgrade paging mode from the command line") Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/9f66d2b58c8052d4055e90b8477ee55d9a0914f9.1698564026.git.christophe.jaillet@wanadoo.fr Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-09-05riscv: Introduce virtual kernel mapping KASLRAlexandre Ghiti
KASLR implementation relies on a relocatable kernel so that we can move the kernel mapping. The seed needed to virtually move the kernel is taken from the device tree, so we rely on the bootloader to provide a correct seed. Zkr could be used unconditionnally instead if implemented, but that's for another patch. Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Tested-by: Conor Dooley <conor.dooley@microchip.com> Tested-by: Song Shuai <songshuaishuai@tinylab.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sami Tolvanen <samitolvanen@google.com> Link: https://lore.kernel.org/r/20230722123850.634544-2-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-05-09riscv: Fix orphan section warnings caused by kernel/piAlexandre Ghiti
kernel/pi gives rise to a lot of new sections that end up orphans: the first attempt to fix that tried to enumerate them all in the linker script, but kernel test robot with a random config keeps finding more of them. So prefix all those sections with .init.pi instead of only .init in order to be able to easily catch them all in the linker script. Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/oe-kbuild-all/202304301606.Cgp113Ha-lkp@intel.com/ Fixes: 26e7aacb83df ("riscv: Allow to downgrade paging mode from the command line") Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20230504120759.18730-1-alexghiti@rivosinc.com Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-04-26riscv: Allow to downgrade paging mode from the command lineAlexandre Ghiti
Add 2 early command line parameters that allow to downgrade satp mode (using the same naming as x86): - "no5lvl": use a 4-level page table (down from sv57 to sv48) - "no4lvl": use a 3-level page table (down from sv57/sv48 to sv39) Note that going through the device tree to get the kernel command line works with ACPI too since the efi stub creates a device tree anyway with the command line. In KASAN kernels, we can't use the libfdt that early in the boot process since we are not ready to execute instrumented functions. So instead of using the "generic" libfdt, we compile our own versions of those functions that are not instrumented and that are prefixed so that they do not conflict with the generic ones. We also need the non-instrumented versions of the string functions and the prefixed versions of memcpy/memmove. This is largely inspired by commit aacd149b6238 ("arm64: head: avoid relocating the kernel twice for KASLR") from which I removed compilation flags that were not relevant to RISC-V at the moment (LTO, SCS). Also note that we have to link with -z norelro to avoid ld.lld to throw a warning with the new .got sections, like in commit 311bea3cb9ee ("arm64: link with -z norelro for LLD or aarch64-elf"). Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Tested-by: Björn Töpel <bjorn@rivosinc.com> Reviewed-by: Björn Töpel <bjorn@rivosinc.com> Link: https://lore.kernel.org/r/20230424092313.178699-2-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>