kernel.git/arch/riscv/kernel/entry.S, branch linux-6.19.y

riscv: entry: fix typo in comment 'instruciton' -> 'instruction'

2025-10-10T01:36:45Z

Fix a typo in a comment in the RISC-V entry.S. Signed-off-by: Florian Schmaus Link: https://lore.kernel.org/r/20251006093742.53925-1-flo@geekplace.eu [pjw@kernel.org: wrote a basic patch description] Signed-off-by: Paul Walmsley

riscv: errata: Fix the PAUSE Opcode for MIPS P8700

2025-09-19T16:33:56Z

Add ERRATA_MIPS and ERRATA_MIPS_P8700_PAUSE_OPCODE configs. Handle errata for the MIPS PAUSE instruction. Signed-off-by: Djordje Todorovic Signed-off-by: Aleksandar Rikalo Signed-off-by: Raj Vishwanathan4 Signed-off-by: Aleksa Paunovic Reviewed-by: Alexandre Ghiti Link: https://lore.kernel.org/r/20250724-p8700-pause-v5-7-a6cbbe1c3412@htecgroup.com [pjw@kernel.org: updated to apply and compile; fixed a checkpatch issue] Signed-off-by: Paul Walmsley

riscv: use lw when reading int cpu in new_vmalloc_check

2025-09-05T21:30:45Z

REG_L is wrong, because thread_info.cpu is 32-bit, not xlen-bit wide. The struct currently has a hole after cpu, so little endian accesses seemed fine. Fixes: 503638e0babf ("riscv: Stop emitting preventive sfence.vma for new vmalloc mappings") Cc: stable@vger.kernel.org Reviewed-by: Alexandre Ghiti Signed-off-by: Radim Krčmář Link: https://lore.kernel.org/r/20250725165410.2896641-4-rkrcmar@ventanamicro.com Signed-off-by: Paul Walmsley

stackleak: Rename STACKLEAK to KSTACK_ERASE

2025-07-22T04:35:01Z

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

Merge tag 'riscv-for-linus-6.16-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2025-06-07T01:05:18Z

Pull RISC-V updates from Palmer Dabbelt: - Support for the FWFT SBI extension, which is part of SBI 3.0 and a dependency for many new SBI and ISA extensions - Support for getrandom() in the VDSO - Support for mseal - Optimized routines for raid6 syndrome and recovery calculations - kexec_file() supports loading Image-formatted kernel binaries - Improvements to the instruction patching framework to allow for atomic instruction patching, along with rules as to how systems need to behave in order to function correctly - Support for a handful of new ISA extensions: Svinval, Zicbop, Zabha, some SiFive vendor extensions - Various fixes and cleanups, including: misaligned access handling, perf symbol mangling, module loading, PUD THPs, and improved uaccess routines * tag 'riscv-for-linus-6.16-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (69 commits) riscv: uaccess: Only restore the CSR_STATUS SUM bit RISC-V: vDSO: Wire up getrandom() vDSO implementation riscv: enable mseal sysmap for RV64 raid6: Add RISC-V SIMD syndrome and recovery calculations riscv: mm: Add support for Svinval extension RISC-V: Documentation: Add enough title underlines to CMODX riscv: Improve Kconfig help for RISCV_ISA_V_PREEMPTIVE MAINTAINERS: Update Atish's email address riscv: uaccess: do not do misaligned accesses in get/put_user() riscv: process: use unsigned int instead of unsigned long for put_user() riscv: make unsafe user copy routines use existing assembly routines riscv: hwprobe: export Zabha extension riscv: Make regs_irqs_disabled() more clear perf symbols: Ignore mapping symbols on riscv RISC-V: Kconfig: Fix help text of CMDLINE_EXTEND riscv: module: Optimize PLT/GOT entry counting riscv: Add support for PUD THP riscv: xchg: Prefetch the destination word for sc.w riscv: Add ARCH_HAS_PREFETCH[W] support with Zicbop riscv: Add support for Zicbop ...

riscv: uaccess: Only restore the CSR_STATUS SUM bit

2025-06-05T21:03:17Z

During switch to csrs will OR the value of the register into the corresponding csr. In this case we're only interested in restoring the SUM bit not the entire register. Signed-off-by: Cyril Bur Link: https://lore.kernel.org/r/20250522160954.429333-1-cyrilbur@tenstorrent.com Co-developed-by: Alexandre Ghiti Signed-off-by: Alexandre Ghiti Fixes: 788aa64c01f1 ("riscv: save the SR_SUM status over switches") Link: https://lore.kernel.org/r/20250602121543.1544278-1-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt

riscv: save the SR_SUM status over switches

2025-05-08T17:01:00Z

When threads/tasks are switched we need to ensure the old execution's SR_SUM state is saved and the new thread has the old SR_SUM state restored. The issue was seen under heavy load especially with the syz-stress tool running, with crashes as follows in schedule_tail: Unable to handle kernel access to user memory without uaccess routines at virtual address 000000002749f0d0 Oops [#1] Modules linked in: CPU: 1 PID: 4875 Comm: syz-executor.0 Not tainted 5.12.0-rc2-syzkaller-00467-g0d7588ab9ef9 #0 Hardware name: riscv-virtio,qemu (DT) epc : schedule_tail+0x72/0xb2 kernel/sched/core.c:4264 ra : task_pid_vnr include/linux/sched.h:1421 [inline] ra : schedule_tail+0x70/0xb2 kernel/sched/core.c:4264 epc : ffffffe00008c8b0 ra : ffffffe00008c8ae sp : ffffffe025d17ec0 gp : ffffffe005d25378 tp : ffffffe00f0d0000 t0 : 0000000000000000 t1 : 0000000000000001 t2 : 00000000000f4240 s0 : ffffffe025d17ee0 s1 : 000000002749f0d0 a0 : 000000000000002a a1 : 0000000000000003 a2 : 1ffffffc0cfac500 a3 : ffffffe0000c80cc a4 : 5ae9db91c19bbe00 a5 : 0000000000000000 a6 : 0000000000f00000 a7 : ffffffe000082eba s2 : 0000000000040000 s3 : ffffffe00eef96c0 s4 : ffffffe022c77fe0 s5 : 0000000000004000 s6 : ffffffe067d74e00 s7 : ffffffe067d74850 s8 : ffffffe067d73e18 s9 : ffffffe067d74e00 s10: ffffffe00eef96e8 s11: 000000ae6cdf8368 t3 : 5ae9db91c19bbe00 t4 : ffffffc4043cafb2 t5 : ffffffc4043cafba t6 : 0000000000040000 status: 0000000000000120 badaddr: 000000002749f0d0 cause: 000000000000000f Call Trace: [] schedule_tail+0x72/0xb2 kernel/sched/core.c:4264 [] ret_from_exception+0x0/0x14 Dumping ftrace buffer: (ftrace buffer empty) ---[ end trace b5f8f9231dc87dda ]--- The issue comes from the put_user() in schedule_tail (kernel/sched/core.c) doing the following: asmlinkage __visible void schedule_tail(struct task_struct *prev) { ... if (current->set_child_tid) put_user(task_pid_vnr(current), current->set_child_tid); ... } the put_user() macro causes the code sequence to come out as follows: 1: __enable_user_access() 2: reg = task_pid_vnr(current); 3: *current->set_child_tid = reg; 4: __disable_user_access() The problem is that we may have a sleeping function as argument which could clear SR_SUM causing the panic above. This was fixed by evaluating the argument of the put_user() macro outside the user-enabled section in commit 285a76bb2cf5 ("riscv: evaluate put_user() arg before enabling user access")" In order for riscv to take advantage of unsafe_get/put_XXX() macros and to avoid the same issue we had with put_user() and sleeping functions we must ensure code flow can go through switch_to() from within a region of code with SR_SUM enabled and come back with SR_SUM still enabled. This patch addresses the problem allowing future work to enable full use of unsafe_get/put_XXX() macros without needing to take a CSR bit flip cost on every access. Make switch_to() save and restore SR_SUM. Reported-by: syzbot+e74b94fe601ab9552d69@syzkaller.appspotmail.com Signed-off-by: Ben Dooks Signed-off-by: Cyril Bur Reviewed-by: Alexandre Ghiti Reviewed-by: Deepak Gupta Link: https://lore.kernel.org/r/20250410070526.3160847-2-cyrilbur@tenstorrent.com Signed-off-by: Palmer Dabbelt

riscv: entry: Split ret_from_fork() into user and kernel

2025-04-29T06:27:10Z

This function was unified into a single function in commit ab9164dae273 ("riscv: entry: Consolidate ret_from_kernel_thread into ret_from_fork"). However that imposed a performance degradation. Partially reverting this commit to have ret_from_fork() split again, results in a 1% increase on the number of times fork is able to be called per second. Signed-off-by: Charlie Jenkins Signed-off-by: Thomas Gleixner Acked-by: Alexandre Ghiti Link: https://lore.kernel.org/all/20250320-riscv_optimize_entry-v6-2-63e187e26041@rivosinc.com

riscv: entry: Convert ret_from_fork() to C

2025-04-29T06:27:10Z

Move the main section of ret_from_fork() to C to allow inlining of syscall_exit_to_user_mode(). Signed-off-by: Charlie Jenkins Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Ghiti Link: https://lore.kernel.org/all/20250320-riscv_optimize_entry-v6-1-63e187e26041@rivosinc.com

riscv: use local label names instead of global ones in assembly

2025-01-08T18:46:14Z

Local labels should be prefix by '.L' or they'll be exported in the symbol table. Additionally, this messes up the backtrace by displaying an incorrect symbol: ... [ 12.751810] [] _copy_from_user+0x28/0xc2 [ 12.752035] [] handle_misaligned_load+0x1ca/0x2fc [ 12.752310] [] do_trap_load_misaligned+0x24/0xee [ 12.752596] [] _new_vmalloc_restore_context_a0+0xc2/0xce After: ... [ 10.243916] [] _copy_from_user+0x28/0xc2 [ 10.244026] [] handle_misaligned_load+0x1ca/0x2fc [ 10.244150] [] do_trap_load_misaligned+0x24/0xee [ 10.244268] [] handle_exception+0x146/0x152 Signed-off-by: Clément Léger Reviewed-by: Alexandre Ghiti Fixes: 503638e0babf3 ("riscv: Stop emitting preventive sfence.vma for new vmalloc mappings") Link: https://lore.kernel.org/r/20250103141814.508865-1-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt