diff options
Diffstat (limited to 'arch/riscv/kernel/alternative.c')
| -rw-r--r-- | arch/riscv/kernel/alternative.c | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/arch/riscv/kernel/alternative.c b/arch/riscv/kernel/alternative.c index a7d26a00beea..2354c69dc7d1 100644 --- a/arch/riscv/kernel/alternative.c +++ b/arch/riscv/kernel/alternative.c @@ -11,10 +11,14 @@ #include <linux/cpu.h> #include <linux/uaccess.h> #include <asm/alternative.h> +#include <asm/module.h> #include <asm/sections.h> +#include <asm/vdso.h> #include <asm/vendorid_list.h> #include <asm/sbi.h> #include <asm/csr.h> +#include <asm/insn.h> +#include <asm/patch.h> struct cpu_manufacturer_info_t { unsigned long vendor_id; @@ -53,6 +57,88 @@ static void __init_or_module riscv_fill_cpu_mfr_info(struct cpu_manufacturer_inf } } +static u32 riscv_instruction_at(void *p) +{ + u16 *parcel = p; + + return (u32)parcel[0] | (u32)parcel[1] << 16; +} + +static void riscv_alternative_fix_auipc_jalr(void *ptr, u32 auipc_insn, + u32 jalr_insn, int patch_offset) +{ + u32 call[2] = { auipc_insn, jalr_insn }; + s32 imm; + + /* get and adjust new target address */ + imm = riscv_insn_extract_utype_itype_imm(auipc_insn, jalr_insn); + imm -= patch_offset; + + /* update instructions */ + riscv_insn_insert_utype_itype_imm(&call[0], &call[1], imm); + + /* patch the call place again */ + patch_text_nosync(ptr, call, sizeof(u32) * 2); +} + +static void riscv_alternative_fix_jal(void *ptr, u32 jal_insn, int patch_offset) +{ + s32 imm; + + /* get and adjust new target address */ + imm = riscv_insn_extract_jtype_imm(jal_insn); + imm -= patch_offset; + + /* update instruction */ + riscv_insn_insert_jtype_imm(&jal_insn, imm); + + /* patch the call place again */ + patch_text_nosync(ptr, &jal_insn, sizeof(u32)); +} + +void riscv_alternative_fix_offsets(void *alt_ptr, unsigned int len, + int patch_offset) +{ + int num_insn = len / sizeof(u32); + int i; + + for (i = 0; i < num_insn; i++) { + u32 insn = riscv_instruction_at(alt_ptr + i * sizeof(u32)); + + /* + * May be the start of an auipc + jalr pair + * Needs to check that at least one more instruction + * is in the list. + */ + if (riscv_insn_is_auipc(insn) && i < num_insn - 1) { + u32 insn2 = riscv_instruction_at(alt_ptr + (i + 1) * sizeof(u32)); + + if (!riscv_insn_is_jalr(insn2)) + continue; + + /* if instruction pair is a call, it will use the ra register */ + if (RV_EXTRACT_RD_REG(insn) != 1) + continue; + + riscv_alternative_fix_auipc_jalr(alt_ptr + i * sizeof(u32), + insn, insn2, patch_offset); + i++; + } + + if (riscv_insn_is_jal(insn)) { + s32 imm = riscv_insn_extract_jtype_imm(insn); + + /* Don't modify jumps inside the alternative block */ + if ((alt_ptr + i * sizeof(u32) + imm) >= alt_ptr && + (alt_ptr + i * sizeof(u32) + imm) < (alt_ptr + len)) + continue; + + riscv_alternative_fix_jal(alt_ptr + i * sizeof(u32), + insn, patch_offset); + } + } +} + /* * This is called very early in the boot process (directly after we run * a feature detect on the boot CPU). No need to worry about other CPUs @@ -77,6 +163,31 @@ static void __init_or_module _apply_alternatives(struct alt_entry *begin, stage); } +#ifdef CONFIG_MMU +static void __init apply_vdso_alternatives(void) +{ + const Elf_Ehdr *hdr; + const Elf_Shdr *shdr; + const Elf_Shdr *alt; + struct alt_entry *begin, *end; + + hdr = (Elf_Ehdr *)vdso_start; + shdr = (void *)hdr + hdr->e_shoff; + alt = find_section(hdr, shdr, ".alternative"); + if (!alt) + return; + + begin = (void *)hdr + alt->sh_offset, + end = (void *)hdr + alt->sh_offset + alt->sh_size, + + _apply_alternatives((struct alt_entry *)begin, + (struct alt_entry *)end, + RISCV_ALTERNATIVES_BOOT); +} +#else +static void __init apply_vdso_alternatives(void) { } +#endif + void __init apply_boot_alternatives(void) { /* If called on non-boot cpu things could go wrong */ @@ -85,6 +196,8 @@ void __init apply_boot_alternatives(void) _apply_alternatives((struct alt_entry *)__alt_start, (struct alt_entry *)__alt_end, RISCV_ALTERNATIVES_BOOT); + + apply_vdso_alternatives(); } /* |