From e72994b41f6c7770318cdbf9f9065fae0ae3f31f Mon Sep 17 00:00:00 2001 From: Heiko Stuebner Date: Mon, 19 Dec 2022 22:27:55 +0100 Subject: [PATCH v4 3/5] RISC-V: fix jal addresses in patched alternatives Alternatives live in a different section, so addresses used by jal instructions will point to wrong locations after the patch got applied. Similar to arm64, adjust the location to consider that offset. Signed-off-by: Heiko Stuebner --- arch/riscv/kernel/alternative.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/arch/riscv/kernel/alternative.c b/arch/riscv/kernel/alternative.c index 6212ea0eed72..985c284fe9f4 100644 --- a/arch/riscv/kernel/alternative.c +++ b/arch/riscv/kernel/alternative.c @@ -79,6 +79,21 @@ static void riscv_alternative_fix_auipc_jalr(void *ptr, u32 auipc_insn, 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 instructions */ + 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) { @@ -106,6 +121,18 @@ void riscv_alternative_fix_offsets(void *alt_ptr, unsigned int len, riscv_alternative_fix_auipc_jalr(alt_ptr + i * sizeof(u32), insn, insn2, patch_offset); } + + 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); + } } } -- 2.35.1