From: Heiko Stuebner <heiko.stuebner@xxxxxxxx> Alternatives live in a different section, so addresses used by call functions will point to wrong locations after the patch got applied. Similar to arm64, adjust the location to consider that offset. Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> Signed-off-by: Heiko Stuebner <heiko.stuebner@xxxxxxxx> --- arch/riscv/include/asm/alternative.h | 3 ++ arch/riscv/kernel/alternative.c | 72 ++++++++++++++++++++++++++++ arch/riscv/kernel/cpufeature.c | 11 ++++- 3 files changed, 84 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h index 6511dd73e812..c58ec3cc4bc3 100644 --- a/arch/riscv/include/asm/alternative.h +++ b/arch/riscv/include/asm/alternative.h @@ -27,6 +27,9 @@ void __init apply_boot_alternatives(void); void __init apply_early_boot_alternatives(void); void apply_module_alternatives(void *start, size_t length); +void riscv_alternative_fix_auipc_jalr(void *alt_ptr, unsigned int len, + int patch_offset); + struct alt_entry { void *old_ptr; /* address of original instruciton or data */ void *alt_ptr; /* address of replacement instruction or data */ diff --git a/arch/riscv/kernel/alternative.c b/arch/riscv/kernel/alternative.c index a7d26a00beea..292cc42dc3be 100644 --- a/arch/riscv/kernel/alternative.c +++ b/arch/riscv/kernel/alternative.c @@ -15,6 +15,8 @@ #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 +55,76 @@ static void __init_or_module riscv_fill_cpu_mfr_info(struct cpu_manufacturer_inf } } +static unsigned int riscv_instruction_at(void *p, unsigned int offset) +{ + u16 *parcel = p + (offset * sizeof(u32)); + + return (unsigned int)parcel[0] | (unsigned int)parcel[1] << 16; +} + +static inline bool riscv_insn_is_auipc_jalr(u32 insn1, u32 insn2) +{ + return riscv_insn_is_auipc(insn1) && riscv_insn_is_jalr(insn2); +} + +#define JALR_SIGN_MASK BIT(RV_I_IMM_SIGN_OPOFF - RV_I_IMM_11_0_OPOFF) +#define AUIPC_PAD (0x00001000) + +#define to_jalr_imm(value) \ + ((value & RV_I_IMM_11_0_MASK) << RV_I_IMM_11_0_OPOFF) + +#define to_auipc_imm(value) \ + ((value & JALR_SIGN_MASK) ? \ + ((value & RV_U_IMM_31_12_MASK) + AUIPC_PAD) : \ + (value & RV_U_IMM_31_12_MASK)) + +void riscv_alternative_fix_auipc_jalr(void *alt_ptr, unsigned int len, + int patch_offset) +{ + int num_instr = len / sizeof(u32); + unsigned int call[2]; + int i; + int imm; + u32 rd1; + + /* + * stop one instruction before the end, as we're checking + * for auipc + jalr + */ + for (i = 0; i < num_instr - 1; i++) { + u32 inst1 = riscv_instruction_at(alt_ptr, i); + u32 inst2 = riscv_instruction_at(alt_ptr, i + 1); + + if (!riscv_insn_is_auipc_jalr(inst1, inst2)) + continue; + + /* call will use ra register */ + rd1 = RV_EXTRACT_RD_REG(inst1); + if (rd1 != 1) + continue; + + /* get and adjust new target address */ + imm = RV_EXTRACT_UTYPE_IMM(inst1); + imm += RV_EXTRACT_ITYPE_IMM(inst2); + imm -= patch_offset; + + /* pick the original auipc + jalr */ + call[0] = inst1; + call[1] = inst2; + + /* drop the old IMMs */ + call[0] &= ~(RV_U_IMM_31_12_MASK); + call[1] &= ~(RV_I_IMM_11_0_MASK << RV_I_IMM_11_0_OPOFF); + + /* add the adapted IMMs */ + call[0] |= to_auipc_imm(imm); + call[1] |= to_jalr_imm(imm); + + /* patch the call place again */ + patch_text_nosync(alt_ptr + i * sizeof(u32), call, 8); + } +} + /* * 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 diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 694267d1fe81..ba62a4ff5ccd 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -316,8 +316,15 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin, } tmp = (1U << alt->errata_id); - if (cpu_req_feature & tmp) - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len); + if (cpu_req_feature & tmp) { + /* do the basic patching */ + patch_text_nosync(alt->old_ptr, alt->alt_ptr, + alt->alt_len); + + riscv_alternative_fix_auipc_jalr(alt->old_ptr, + alt->alt_len, + alt->old_ptr - alt->alt_ptr); + } } } #endif -- 2.35.1