linux-kernel - [PATCH v2 3/4] LoongArch: Stop using undocumented assembler options

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Date:   Thu, 28 Jul 2022 20:03:17 +0800
From:   Xi Ruoyao <xry111@...111.site>
To:     loongarch@...ts.linux.dev
Cc:     linux-kernel@...r.kernel.org, WANG Xuerui <kernel@...0n.name>,
        Huacai Chen <chenhuacai@...nel.org>,
        Youling Tang <tangyouling@...ngson.cn>,
        Jinyang He <hejinyang@...ngson.cn>
Subject: [PATCH v2 3/4] LoongArch: Stop using undocumented assembler options

Now we can handle GOT and GOT-based relocations properly, remove the
undocumented `-Wa,-mla-{global,local}-with-{pcrel,abs}` assembler hacks.

And, -fplt is the default of all supported compilers (GCC, and maybe
Clang in the future), so it can be removed as well.

Adjust assembly code to explicitly use "la.pcrel" where necessary.

Signed-off-by: Xi Ruoyao <xry111@...111.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