kernel.git/arch/loongarch/kernel/process.c, branch linux-6.19.y

LoongArch: Adjust process management for 32BIT/64BIT

2025-12-08T10:09:17Z

Adjust process management for both 32BIT and 64BIT, including: CPU context switching, FPU loading/restoring, process dumping and process tracing routines. Q: Why modify switch.S? A: LoongArch32 has no ldptr.d/stptr.d instructions, and asm offsets of thead_struct members are too large to be filled in the 12b immediate field of ld.w/st.w. Reviewed-by: Arnd Bergmann Signed-off-by: Jiaxun Yang Signed-off-by: Huacai Chen

LoongArch: Fix arch_dup_task_struct() for CONFIG_RANDSTRUCT

2025-12-06T02:39:48Z

Now the optimized version of arch_dup_task_struct() for LoongArch assumes 'thread' is the last member of 'task_struct'. But this is not true if CONFIG_RANDSTRUCT is enabled after Linux-6.16. So fix the arch_dup_task_struct() function for CONFIG_RANDSTRUCT by copying the whole 'task_struct'. Cc: stable@vger.kernel.org # 6.16+ Signed-off-by: Huacai Chen

arch: copy_thread: pass clone_flags as u64

2025-09-01T13:31:34Z

With the introduction of clone3 in commit 7f192e3cd316 ("fork: add clone3") the effective bit width of clone_flags on all architectures was increased from 32-bit to 64-bit, with a new type of u64 for the flags. However, for most consumers of clone_flags the interface was not changed from the previous type of unsigned long. While this works fine as long as none of the new 64-bit flag bits (CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still undesirable in terms of the principle of least surprise. Thus, this commit fixes all relevant interfaces of the copy_thread function that is called from copy_process to consistently pass clone_flags as u64, so that no truncation to 32-bit integers occurs on 32-bit architectures. Signed-off-by: Simon Schuster Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-3-53fcf5577d57@siemens-energy.com Fixes: c5febea0956fd387 ("fork: Pass struct kernel_clone_args into copy_thread") Acked-by: Guo Ren (Alibaba Damo Academy) Acked-by: Andreas Larsson # sparc Acked-by: David Hildenbrand Acked-by: Geert Uytterhoeven # m68k Reviewed-by: Arnd Bergmann Signed-off-by: Christian Brauner

LoongArch: entry: Fix include order

2025-05-07T09:05:57Z

Reorder some introduced include headers to keep alphabetical order. Fixes: 7ace1602abf2 ("LoongArch: entry: Migrate ret_from_fork() to C") Signed-off-by: Charlie Jenkins Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250507-loongarch_include_order-v1-1-e8aada6a3da8@rivosinc.com

LoongArch: entry: Migrate ret_from_fork() to C

2025-04-29T06:27:10Z

LoongArch is the only architecture that calls syscall_exit_to_user_mode() from assembly. Move the call into C so that this function can be inlined across all architectures. Signed-off-by: Charlie Jenkins Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250320-riscv_optimize_entry-v6-3-63e187e26041@rivosinc.com

LoongArch: Don't crash in stack_top() for tasks without vDSO

2024-10-21T14:11:19Z

Not all tasks have a vDSO mapped, for example kthreads never do. If such a task ever ends up calling stack_top(), it will derefence the NULL vdso pointer and crash. This can for example happen when using kunit: [<9000000000203874>] stack_top+0x58/0xa8 [<90000000002956cc>] arch_pick_mmap_layout+0x164/0x220 [<90000000003c284c>] kunit_vm_mmap_init+0x108/0x12c [<90000000003c1fbc>] __kunit_add_resource+0x38/0x8c [<90000000003c2704>] kunit_vm_mmap+0x88/0xc8 [<9000000000410b14>] usercopy_test_init+0xbc/0x25c [<90000000003c1db4>] kunit_try_run_case+0x5c/0x184 [<90000000003c3d54>] kunit_generic_run_threadfn_adapter+0x24/0x48 [<900000000022e4bc>] kthread+0xc8/0xd4 [<9000000000200ce8>] ret_from_kernel_thread+0xc/0xa4 Fixes: 803b0fc5c3f2 ("LoongArch: Add process management") Signed-off-by: Thomas Weißschuh Signed-off-by: Huacai Chen

LoongArch: Fix and simplify fcsr initialization on execve()

2024-01-17T04:43:08Z

There has been a lingering bug in LoongArch Linux systems causing some GCC tests to intermittently fail (see Closes link). I've made a minimal reproducer: zsh% cat measure.s .align 4 .globl _start _start: movfcsr2gr $a0, $fcsr0 bstrpick.w $a0, $a0, 16, 16 beqz $a0, .ok break 0 .ok: li.w $a7, 93 syscall 0 zsh% cc mesaure.s -o measure -nostdlib zsh% echo $((1.0/3)) 0.33333333333333331 zsh% while ./measure; do ; done This while loop should not stop as POSIX is clear that execve must set fenv to the default, where FCSR should be zero. But in fact it will just stop after running for a while (normally less than 30 seconds). Note that "$((1.0/3))" is needed to reproduce this issue because it raises FE_INVALID and makes fcsr0 non-zero. The problem is we are currently relying on SET_PERSONALITY2() to reset current->thread.fpu.fcsr. But SET_PERSONALITY2() is executed before start_thread which calls lose_fpu(0). We can see if kernel preempt is enabled, we may switch to another thread after SET_PERSONALITY2() but before lose_fpu(0). Then bad thing happens: during the thread switch the value of the fcsr0 register is stored into current->thread.fpu.fcsr, making it dirty again. The issue can be fixed by setting current->thread.fpu.fcsr after lose_fpu(0) because lose_fpu() clears TIF_USEDFPU, then the thread switch won't touch current->thread.fpu.fcsr. The only other architecture setting FCSR in SET_PERSONALITY2() is MIPS. I've ran a similar test on MIPS with mainline kernel and it turns out MIPS is buggy, too. Anyway MIPS do this for supporting different FP flavors (NaN encodings, etc.) which do not exist on LoongArch. So for LoongArch, we can simply remove the current->thread.fpu.fcsr setting from SET_PERSONALITY2() and do it in start_thread(), after lose_fpu(0). The while loop failing with the mainline kernel has survived one hour after this change on LoongArch. Fixes: 803b0fc5c3f2baa ("LoongArch: Add process management") Closes: https://github.com/loongson-community/discussions/issues/7 Link: https://lore.kernel.org/linux-mips/7a6aa1bbdbbe2e63ae96ff163fab0349f58f1b9e.camel@xry111.site/ Cc: stable@vger.kernel.org Signed-off-by: Xi Ruoyao Signed-off-by: Huacai Chen

LoongArch: Fix some build warnings with W=1

2023-09-20T06:26:28Z

There are some building warnings when building LoongArch kernel with W=1 as following, this patch fixes them. arch/loongarch/kernel/acpi.c:284:13: warning: no previous prototype for ‘acpi_numa_arch_fixup’ [-Wmissing-prototypes] 284 | void __init acpi_numa_arch_fixup(void) {} | ^~~~~~~~~~~~~~~~~~~~ arch/loongarch/kernel/time.c:32:13: warning: no previous prototype for ‘constant_timer_interrupt’ [-Wmissing-prototypes] 32 | irqreturn_t constant_timer_interrupt(int irq, void *data) | ^~~~~~~~~~~~~~~~~~~~~~~~ arch/loongarch/kernel/traps.c:496:25: warning: no previous prototype for 'do_fpe' [-Wmissing-prototypes] 496 | asmlinkage void noinstr do_fpe(struct pt_regs *regs | ^~~~~~ arch/loongarch/kernel/traps.c:813:22: warning: variable ‘opcode’ set but not used [-Wunused-but-set-variable] 813 | unsigned int opcode; | ^~~~~~ arch/loongarch/kernel/signal.c:895:14: warning: no previous prototype for ‘get_sigframe’ [-Wmissing-prototypes] 895 | void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, | ^~~~~~~~~~~~ arch/loongarch/kernel/syscall.c:21:40: warning: initialized field overwritten [-Woverride-init] 21 | #define __SYSCALL(nr, call) [nr] = (call), | ^ arch/loongarch/kernel/syscall.c:40:14: warning: no previous prototype for ‘do_syscall’ [-Wmissing-prototypes] 40 | void noinstr do_syscall(struct pt_regs *regs) | ^~~~~~~~~~ arch/loongarch/kernel/smp.c:502:17: warning: no previous prototype for ‘start_secondary’ [-Wmissing-prototypes] 502 | asmlinkage void start_secondary(void) | ^~~~~~~~~~~~~~~ arch/loongarch/kernel/process.c:309:15: warning: no previous prototype for ‘arch_align_stack’ [-Wmissing-prototypes] 309 | unsigned long arch_align_stack(unsigned long sp) | ^~~~~~~~~~~~~~~~ arch/loongarch/kernel/topology.c:13:5: warning: no previous prototype for ‘arch_register_cpu’ [-Wmissing-prototypes] 13 | int arch_register_cpu(int cpu) | ^~~~~~~~~~~~~~~~~ arch/loongarch/kernel/topology.c:27:6: warning: no previous prototype for ‘arch_unregister_cpu’ [-Wmissing-prototypes] 27 | void arch_unregister_cpu(int cpu) | ^~~~~~~~~~~~~~~~~~~ arch/loongarch/kernel/module-sections.c:103:5: warning: no previous prototype for ‘module_frob_arch_sections’ [-Wmissing-prototypes] 103 | int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, | ^~~~~~~~~~~~~~~~~~~~~~~~~ arch/loongarch/mm/hugetlbpage.c:56:5: warning: no previous prototype for ‘is_aligned_hugepage_range’ [-Wmissing-prototypes] 56 | int is_aligned_hugepage_range(unsigned long addr, unsigned long len) | ^~~~~~~~~~~~~~~~~~~~~~~~~ Signed-off-by: Bibo Mao Signed-off-by: Huacai Chen

Merge tag 'loongarch-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson

2023-09-08T19:16:52Z

Pull LoongArch updates from Huacai Chen: - Allow usage of LSX/LASX in the kernel, and use them for SIMD-optimized RAID5/RAID6 routines - Add Loongson Binary Translation (LBT) extension support - Add basic KGDB & KDB support - Add building with kcov coverage - Add KFENCE (Kernel Electric-Fence) support - Add KASAN (Kernel Address Sanitizer) support - Some bug fixes and other small changes - Update the default config file * tag 'loongarch-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson: (25 commits) LoongArch: Update Loongson-3 default config file LoongArch: Add KASAN (Kernel Address Sanitizer) support LoongArch: Simplify the processing of jumping new kernel for KASLR kasan: Add (pmd|pud)_init for LoongArch zero_(pud|p4d)_populate process kasan: Add __HAVE_ARCH_SHADOW_MAP to support arch specific mapping LoongArch: Add KFENCE (Kernel Electric-Fence) support LoongArch: Get partial stack information when providing regs parameter LoongArch: mm: Add page table mapped mode support for virt_to_page() kfence: Defer the assignment of the local variable addr LoongArch: Allow building with kcov coverage LoongArch: Provide kaslr_offset() to get kernel offset LoongArch: Add basic KGDB & KDB support LoongArch: Add Loongson Binary Translation (LBT) extension support raid6: Add LoongArch SIMD recovery implementation raid6: Add LoongArch SIMD syndrome calculation LoongArch: Add SIMD-optimized XOR routines LoongArch: Allow usage of LSX/LASX in the kernel LoongArch: Define symbol 'fault' as a local label in fpu.S LoongArch: Adjust {copy, clear}_user exception handler behavior LoongArch: Use static defined zero page rather than allocated ...

LoongArch: Add Loongson Binary Translation (LBT) extension support

2023-09-06T14:53:55Z

Loongson Binary Translation (LBT) is used to accelerate binary translation, which contains 4 scratch registers (scr0 to scr3), x86/ARM eflags (eflags) and x87 fpu stack pointer (ftop). This patch support kernel to save/restore these registers, handle the LBT exception and maintain sigcontext. Signed-off-by: Qi Hu Signed-off-by: Huacai Chen