* [PATCH] riscv/runtime-const: Disable linker relaxation for RUNTIME_MAGIC
@ 2026-08-02 17:43 ` Fangrui Song
0 siblings, 0 replies; 7+ messages in thread
From: Fangrui Song @ 2026-08-02 17:43 UTC (permalink / raw)
To: Peter Zijlstra
Cc: K Prateek Nayak, Guo Ren, Palmer Dabbelt, Charlie Jenkins,
linux-riscv, linux-kernel, llvm, Fangrui Song, Nathan Chancellor
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")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://github.com/ClangBuiltLinux/linux/issues/2179
Signed-off-by: Fangrui Song <i@maskray.me>
---
Applies to tip/locking/core; the RISC-V tree (riscv/linux.git) does not
carry ee10b1028129.
arch/riscv/include/asm/runtime-const.h | 2 ++
1 file changed, 2 insertions(+)
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" \
base-commit: 5e601ab3615c86be7c4068ce992f94654693a032
--
2.43.0
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH] riscv/runtime-const: Disable linker relaxation for RUNTIME_MAGIC
2026-08-02 17:43 ` Fangrui Song
@ 2026-08-03 8:27 ` Peter Zijlstra
-1 siblings, 0 replies; 7+ messages in thread
From: Peter Zijlstra @ 2026-08-03 8:27 UTC (permalink / raw)
To: Fangrui Song
Cc: K Prateek Nayak, Guo Ren, Palmer Dabbelt, Charlie Jenkins,
linux-riscv, linux-kernel, llvm, Nathan Chancellor
On Sun, Aug 02, 2026 at 10:43:42AM -0700, Fangrui Song wrote:
> 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")
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Closes: https://github.com/ClangBuiltLinux/linux/issues/2179
> Signed-off-by: Fangrui Song <i@maskray.me>
> ---
> Applies to tip/locking/core; the RISC-V tree (riscv/linux.git) does not
> carry ee10b1028129.
Thanks, I'll stick this on top.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] riscv/runtime-const: Disable linker relaxation for RUNTIME_MAGIC
@ 2026-08-03 8:27 ` Peter Zijlstra
0 siblings, 0 replies; 7+ messages in thread
From: Peter Zijlstra @ 2026-08-03 8:27 UTC (permalink / raw)
To: Fangrui Song
Cc: K Prateek Nayak, Guo Ren, Palmer Dabbelt, Charlie Jenkins,
linux-riscv, linux-kernel, llvm, Nathan Chancellor
On Sun, Aug 02, 2026 at 10:43:42AM -0700, Fangrui Song wrote:
> 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")
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Closes: https://github.com/ClangBuiltLinux/linux/issues/2179
> Signed-off-by: Fangrui Song <i@maskray.me>
> ---
> Applies to tip/locking/core; the RISC-V tree (riscv/linux.git) does not
> carry ee10b1028129.
Thanks, I'll stick this on top.
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] riscv/runtime-const: Disable linker relaxation for RUNTIME_MAGIC
2026-08-02 17:43 ` Fangrui Song
@ 2026-08-03 16:12 ` Nathan Chancellor
-1 siblings, 0 replies; 7+ messages in thread
From: Nathan Chancellor @ 2026-08-03 16:12 UTC (permalink / raw)
To: Fangrui Song
Cc: Peter Zijlstra, K Prateek Nayak, Guo Ren, Palmer Dabbelt,
Charlie Jenkins, linux-riscv, linux-kernel, llvm
On Sun, Aug 02, 2026 at 10:43:42AM -0700, Fangrui Song wrote:
> 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")
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Closes: https://github.com/ClangBuiltLinux/linux/issues/2179
> Signed-off-by: Fangrui Song <i@maskray.me>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Thanks a lot for the quick fix!
> ---
> Applies to tip/locking/core; the RISC-V tree (riscv/linux.git) does not
> carry ee10b1028129.
>
> arch/riscv/include/asm/runtime-const.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> 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" \
>
> base-commit: 5e601ab3615c86be7c4068ce992f94654693a032
> --
> 2.43.0
>
>
--
Cheers,
Nathan
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] riscv/runtime-const: Disable linker relaxation for RUNTIME_MAGIC
@ 2026-08-03 16:12 ` Nathan Chancellor
0 siblings, 0 replies; 7+ messages in thread
From: Nathan Chancellor @ 2026-08-03 16:12 UTC (permalink / raw)
To: Fangrui Song
Cc: Peter Zijlstra, K Prateek Nayak, Guo Ren, Palmer Dabbelt,
Charlie Jenkins, linux-riscv, linux-kernel, llvm
On Sun, Aug 02, 2026 at 10:43:42AM -0700, Fangrui Song wrote:
> 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")
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Closes: https://github.com/ClangBuiltLinux/linux/issues/2179
> Signed-off-by: Fangrui Song <i@maskray.me>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Thanks a lot for the quick fix!
> ---
> Applies to tip/locking/core; the RISC-V tree (riscv/linux.git) does not
> carry ee10b1028129.
>
> arch/riscv/include/asm/runtime-const.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> 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" \
>
> base-commit: 5e601ab3615c86be7c4068ce992f94654693a032
> --
> 2.43.0
>
>
--
Cheers,
Nathan
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 7+ messages in thread
* [tip: locking/core] riscv/runtime-const: Disable linker relaxation for RUNTIME_MAGIC
2026-08-02 17:43 ` Fangrui Song
` (2 preceding siblings ...)
(?)
@ 2026-08-04 10:31 ` tip-bot2 for Fangrui Song
-1 siblings, 0 replies; 7+ messages in thread
From: tip-bot2 for Fangrui Song @ 2026-08-04 10:31 UTC (permalink / raw)
To: linux-tip-commits
Cc: Nathan Chancellor, Fangrui Song, Peter Zijlstra (Intel), x86,
linux-kernel
The following commit has been merged into the locking/core branch of tip:
Commit-ID: 0f289334af68a1331d4a2d2a95799ffa4ff8a046
Gitweb: https://git.kernel.org/tip/0f289334af68a1331d4a2d2a95799ffa4ff8a046
Author: Fangrui Song <i@maskray.me>
AuthorDate: Sun, 02 Aug 2026 10:43:42 -07:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 04 Aug 2026 12:29:45 +02:00
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
---
arch/riscv/include/asm/runtime-const.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/riscv/include/asm/runtime-const.h b/arch/riscv/include/asm/runtime-const.h
index a472ebb..ce2008b 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" \
^ permalink raw reply related [flat|nested] 7+ messages in thread