diff options
| author | Fangrui Song <i@maskray.me> | 2026-08-02 10:43:42 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-08-04 12:29:45 +0200 |
| commit | 0f289334af68a1331d4a2d2a95799ffa4ff8a046 (patch) | |
| tree | 4d1a9665b9c38f82f3ade4c1df2a5364f432b131 | |
| parent | c9c8578ad58e66a64ca887731e2b6ebf9d71174b (diff) | |
riscv/runtime-const: Disable linker relaxation for RUNTIME_MAGIC
Commit ee10b1028129 ("riscv/runtime-const: Replace open-coded
placeholder with RUNTIME_MAGIC") switched the lui + addi[w] placeholder
from hand-encoded immediates to %hi()/%lo() of RUNTIME_MAGIC.
GNU Assembler folds %hi()/%lo() of an absolute expression at assembly
time. LLVM's integrated assembler since 21.1 defers it to the linker
instead, which range checks it: on riscv64 R_RISCV_HI20 must fit a
signed 20-bit field, and RUNTIME_MAGIC (0x89ABCDEF) is a positive 64-bit
value rather than a sign-extended 32-bit one, so it does not:
ld.lld: error: relocation R_RISCV_HI20 out of range: 563901 is not in
[-524288, 524287]
The sequence is patched at runtime and its instruction offsets are
recorded via ".long 1b - .", so the linker must not touch it in the
first place. Add ".option norelax", as is already done for
ALTERNATIVE() and static keys; the integrated assembler then resolves
%hi()/%lo() itself and emits no relocation, restoring the exact
encoding the open-coded placeholder produced.
Fixes: ee10b1028129 ("riscv/runtime-const: Replace open-coded placeholder with RUNTIME_MAGIC")
Closes: https://github.com/ClangBuiltLinux/linux/issues/2179
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Fangrui Song <i@maskray.me>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260802174342.597092-1-i@maskray.me
| -rw-r--r-- | arch/riscv/include/asm/runtime-const.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/runtime-const.h b/arch/riscv/include/asm/runtime-const.h index a472ebbf0971..ce2008bb5227 100644 --- a/arch/riscv/include/asm/runtime-const.h +++ b/arch/riscv/include/asm/runtime-const.h @@ -23,6 +23,7 @@ typeof(sym) __ret; \ asm_inline(".option push\n\t" \ ".option norvc\n\t" \ + ".option norelax\n\t" \ "1:\t" \ "lui %[__ret], %%hi(" RUNTIME_MAGIC ")\n\t" \ "addi %[__ret],%[__ret], %%lo(" RUNTIME_MAGIC ")\n\t" \ @@ -47,6 +48,7 @@ #define RISCV_RUNTIME_CONST_64_PREAMBLE \ ".option push\n\t" \ ".option norvc\n\t" \ + ".option norelax\n\t" \ "1:\t" \ "lui %[__ret], %%hi(" RUNTIME_MAGIC ")\n\t" \ "lui %[__tmp], %%hi(" RUNTIME_MAGIC ")\n\t" \ |