Messages in this thread Patch in this message | | | Subject | [PATCH v4 3/4] LoongArch: Remove -fplt and -Wa,-mla-* from CFLAGS | From | Xi Ruoyao <> | Date | Fri, 29 Jul 2022 16:41:32 +0800 |
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-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 by default if the assembler supports explicit specification for relocations. And, it's not recommended to override the default as the use of assembler macros may limit optimization.
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 <xry111@xry111.site> --- 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
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