RISC-V: fix jal addresses in patched alternatives
From: Heiko Stuebner <heiko.stuebner@...> Date: Mon, 19 Dec 2022 22:27:55 +0100
Commit-Message
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 <heiko.stuebner@...>
Patch-Comment
arch/riscv/kernel/alternative.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)
Statistics
- 27 lines added
- 0 lines removed
Changes
----------------------- arch/riscv/kernel/alternative.c ------------------------
index 6212ea0eed72..985c284fe9f4 100644
@@ -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);
+ }
}
}