diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h index 42d2c42f3cc9..2368d49eb4ef 100644 --- a/arch/riscv/include/asm/fixmap.h +++ b/arch/riscv/include/asm/fixmap.h @@ -27,6 +27,8 @@ enum fixed_addresses { FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1, FIX_PTE, FIX_PMD, + FIX_TEXT_POKE1, + FIX_TEXT_POKE0, FIX_EARLYCON_MEM_BASE, __end_of_fixed_addresses }; diff --git a/arch/riscv/include/asm/patch.h b/arch/riscv/include/asm/patch.h new file mode 100644 index 000000000000..b5918a6e0615 --- /dev/null +++ b/arch/riscv/include/asm/patch.h @@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2020 SiFive + */ + +#ifndef _ASM_RISCV_PATCH_H +#define _ASM_RISCV_PATCH_H + +int riscv_patch_text_nosync(void *addr, const void *insns, size_t len); +int riscv_patch_text(void *addr, u32 insn); + +#endif /* _ASM_RISCV_PATCH_H */ diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index f40205cb9a22..d189bd3d8501 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -4,7 +4,8 @@ # ifdef CONFIG_FTRACE -CFLAGS_REMOVE_ftrace.o = -pg +CFLAGS_REMOVE_ftrace.o = -pg +CFLAGS_REMOVE_patch.o = -pg endif extra-y += head.o @@ -26,6 +27,7 @@ obj-y += traps.o obj-y += riscv_ksyms.o obj-y += stacktrace.o obj-y += cacheinfo.o +obj-y += patch.o obj-$(CONFIG_MMU) += vdso.o vdso/ obj-$(CONFIG_RISCV_M_MODE) += clint.o diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c new file mode 100644 index 000000000000..8a4fc65ee022 --- /dev/null +++ b/arch/riscv/kernel/patch.c @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020 SiFive + */ + +#include +#include +#include +#include +#include +#include +#include + +struct riscv_insn_patch { + void *addr; + u32 insn; + atomic_t cpu_count; +}; + +#ifdef CONFIG_MMU +static DEFINE_RAW_SPINLOCK(patch_lock); + +static void __kprobes *patch_map(void *addr, int fixmap) +{ + uintptr_t uintaddr = (uintptr_t) addr; + struct page *page; + + if (core_kernel_text(uintaddr)) + page = phys_to_page(__pa_symbol(addr)); + else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) + page = vmalloc_to_page(addr); + else + return addr; + + BUG_ON(!page); + + return (void *)set_fixmap_offset(fixmap, page_to_phys(page) + + (uintaddr & ~PAGE_MASK)); +} + +static void __kprobes patch_unmap(int fixmap) +{ + clear_fixmap(fixmap); +} + +static int __kprobes riscv_insn_write(void *addr, const void *insn, size_t len) +{ + void *waddr = addr; + bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; + unsigned long flags = 0; + int ret; + + raw_spin_lock_irqsave(&patch_lock, flags); + + if (across_pages) + patch_map(addr + len, FIX_TEXT_POKE1); + + waddr = patch_map(addr, FIX_TEXT_POKE0); + + ret = probe_kernel_write(waddr, insn, len); + + patch_unmap(FIX_TEXT_POKE0); + + if (across_pages) + patch_unmap(FIX_TEXT_POKE1); + + raw_spin_unlock_irqrestore(&patch_lock, flags); + + return ret; +} +#else +static int __kprobes riscv_insn_write(void *addr, const void *insn, size_t len) +{ + return probe_kernel_write(addr, insn, len); +} +#endif /* CONFIG_MMU */ + +int __kprobes riscv_patch_text_nosync(void *addr, const void *insns, size_t len) +{ + u32 *tp = addr; + int ret; + + ret = riscv_insn_write(tp, insns, len); + + if (!ret) + flush_icache_range((uintptr_t) tp, (uintptr_t) tp + len); + + return ret; +} + +static int __kprobes riscv_patch_text_cb(void *data) +{ + struct riscv_insn_patch *patch = data; + int ret = 0; + + if (atomic_inc_return(&patch->cpu_count) == 1) { + ret = + riscv_patch_text_nosync(patch->addr, &patch->insn, + GET_INSN_LENGTH(patch->insn)); + atomic_inc(&patch->cpu_count); + } else { + while (atomic_read(&patch->cpu_count) <= num_online_cpus()) + cpu_relax(); + smp_mb(); + } + + return ret; +} + +int __kprobes riscv_patch_text(void *addr, u32 insn) +{ + struct riscv_insn_patch patch = { + .addr = addr, + .insn = insn, + .cpu_count = ATOMIC_INIT(0), + }; + + return stop_machine_cpuslocked(riscv_patch_text_cb, + &patch, cpu_online_mask); +}