-fplt is the default of all supported compilers (GCC, and maybe Clang in
the future), so it needs not to be explicitly specified.
-Wa,-mla-* options were used to prevent the assembler from generating
GOT accesses for "la.local" and "la.global" macros. But GCC >= 13 will
generate GOT access explicitly without use of these macros, so these
options are ineffective for symbol addressing in C code with GCC >= 13.
Now we can handle GOT and GOT-based relocations properly, so we can
remove these options and use GOT access for both GCC 12 and 13
(or newer).
GAS <= 2.39 does not support "la.got [reg], [sym] + [offset]" with a
non-zero offset. So in the assembly code we explicitly use "la.pcrel"
instead of "la" (now defaulted to "la.got") where a PC-relative
addressing is suitable, in order to work around this limitation and keep
the compatibility with old toolchains.
Signed-off-by: Xi Ruoyao <[email protected]>
---
arch/loongarch/Makefile | 4 ----
arch/loongarch/kernel/head.S | 10 +++++-----
2 files changed, 5 insertions(+), 9 deletions(-)
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index 039dcc4fe1f3..800349ea9310 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -40,10 +40,6 @@ endif
cflags-y += -G0 -pipe -msoft-float
LDFLAGS_vmlinux += -G0 -static -n -nostdlib
-KBUILD_AFLAGS_KERNEL += -Wa,-mla-global-with-pcrel
-KBUILD_CFLAGS_KERNEL += -Wa,-mla-global-with-pcrel
-KBUILD_AFLAGS_MODULE += -Wa,-mla-global-with-abs
-KBUILD_CFLAGS_MODULE += -fplt -Wa,-mla-global-with-abs,-mla-local-with-abs
cflags-y += -ffreestanding
cflags-y += $(call cc-option, -mno-check-zero-division)
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
index 74ea7bf6c8d6..193329ed6e8c 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -60,17 +60,17 @@ SYM_CODE_START(kernel_entry) # kernel entry point
la.abs t0, 0f
jirl zero, t0, 0
0:
- la t0, __bss_start # clear .bss
+ la.pcrel t0, __bss_start # clear .bss
st.d zero, t0, 0
- la t1, __bss_stop - LONGSIZE
+ la.pcrel t1, __bss_stop - LONGSIZE
1:
addi.d t0, t0, LONGSIZE
st.d zero, t0, 0
bne t0, t1, 1b
- la t0, fw_arg0
+ la.pcrel t0, fw_arg0
st.d a0, t0, 0 # firmware arguments
- la t0, fw_arg1
+ la.pcrel t0, fw_arg1
st.d a1, t0, 0
/* KSave3 used for percpu base, initialized as 0 */
@@ -78,7 +78,7 @@ SYM_CODE_START(kernel_entry) # kernel entry point
/* GPR21 used for percpu base (runtime), initialized as 0 */
or u0, zero, zero
- la tp, init_thread_union
+ la.pcrel tp, init_thread_union
/* Set the SP after an empty pt_regs. */
PTR_LI sp, (_THREAD_SIZE - 32 - PT_SIZE)
PTR_ADD sp, sp, tp
--
2.37.0
On Fri, 2022-07-29 at 10:09 +0800, Xi Ruoyao wrote:
> -fplt is the default of all supported compilers (GCC, and maybe Clang in
> the future), so it needs not to be explicitly specified.
>
> -Wa,-mla-* options were used to prevent the assembler from generating
> GOT accesses for "la.local" and "la.global" macros. But GCC >= 13 will
> generate GOT access explicitly without use of these macros
Will add "by default with an assembler supporting explicit relocations,
and it's not recommended to override the default" here in V4.
> options are ineffective for symbol addressing in C code with GCC >= 13.
> Now we can handle GOT and GOT-based relocations properly, so we can
> remove these options and use GOT access for both GCC 12 and 13
> (or newer).
>
> GAS <= 2.39 does not support "la.got [reg], [sym] + [offset]" with a
> non-zero offset. So in the assembly code we explicitly use "la.pcrel"
> instead of "la" (now defaulted to "la.got") where a PC-relative
> addressing is suitable, in order to work around this limitation and keep
> the compatibility with old toolchains.
>
> Signed-off-by: Xi Ruoyao <[email protected]>
> ---
> arch/loongarch/Makefile | 4 ----
> arch/loongarch/kernel/head.S | 10 +++++-----
> 2 files changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index 039dcc4fe1f3..800349ea9310 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -40,10 +40,6 @@ endif
>
> cflags-y += -G0 -pipe -msoft-float
> LDFLAGS_vmlinux += -G0 -static -n -nostdlib
> -KBUILD_AFLAGS_KERNEL += -Wa,-mla-global-with-pcrel
> -KBUILD_CFLAGS_KERNEL += -Wa,-mla-global-with-pcrel
> -KBUILD_AFLAGS_MODULE += -Wa,-mla-global-with-abs
> -KBUILD_CFLAGS_MODULE += -fplt -Wa,-mla-global-with-abs,-mla-local-with-abs
>
> cflags-y += -ffreestanding
> cflags-y += $(call cc-option, -mno-check-zero-division)
> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> index 74ea7bf6c8d6..193329ed6e8c 100644
> --- a/arch/loongarch/kernel/head.S
> +++ b/arch/loongarch/kernel/head.S
> @@ -60,17 +60,17 @@ SYM_CODE_START(kernel_entry) # kernel entry point
> la.abs t0, 0f
> jirl zero, t0, 0
> 0:
> - la t0, __bss_start # clear .bss
> + la.pcrel t0, __bss_start # clear .bss
> st.d zero, t0, 0
> - la t1, __bss_stop - LONGSIZE
> + la.pcrel t1, __bss_stop - LONGSIZE
> 1:
> addi.d t0, t0, LONGSIZE
> st.d zero, t0, 0
> bne t0, t1, 1b
>
> - la t0, fw_arg0
> + la.pcrel t0, fw_arg0
> st.d a0, t0, 0 # firmware arguments
> - la t0, fw_arg1
> + la.pcrel t0, fw_arg1
> st.d a1, t0, 0
>
> /* KSave3 used for percpu base, initialized as 0 */
> @@ -78,7 +78,7 @@ SYM_CODE_START(kernel_entry) # kernel entry point
> /* GPR21 used for percpu base (runtime), initialized as 0 */
> or u0, zero, zero
>
> - la tp, init_thread_union
> + la.pcrel tp, init_thread_union
> /* Set the SP after an empty pt_regs. */
> PTR_LI sp, (_THREAD_SIZE - 32 - PT_SIZE)
> PTR_ADD sp, sp, tp
--
Xi Ruoyao <[email protected]>
School of Aerospace Science and Technology, Xidian University