Messages in this thread Patches in this message | | | Subject | Re: [PATCH v7 0/5] LoongArch: Support toolchain with new relocation types | From | Xi Ruoyao <> | Date | Tue, 06 Sep 2022 08:32:13 +0800 |
| |
On Thu, 2022-09-01 at 10:17 +0800, Huacai Chen wrote:
> Now all global variable accesses are via got, I think the performance > may be much worse than before when we didn't use explicit-relocs. > I don't know whether "a new code model" or your "(1)(2)(3)" is easier > to implement, but I think it is better to solve the performance issue > before 6.1-rc1.
Hi Huacai,
We've added a GCC option for this at https://gcc.gnu.org/r13-2433. On the kernel side we need a one-line change:
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile index 92c4a52c4c3e..69b39ba3a09d 100644 --- a/arch/loongarch/Makefile +++ b/arch/loongarch/Makefile @@ -54,6 +54,7 @@ LDFLAGS_vmlinux += -G0 -static -n -nostdlib # upgrade the compiler or downgrade the assembler. ifdef CONFIG_AS_HAS_EXPLICIT_RELOCS cflags-y += -mexplicit-relocs +KBUILD_CFLAGS_KERNEL += -mdirect-extern-access else cflags-y += $(call cc-option,-mno-explicit-relocs) KBUILD_AFLAGS_KERNEL += -Wa,-mla-global-with-pcrel And we also need a one-line change in the EFI stub patch (under review):
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 8931ed24379e..8c1225b92492 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -27,7 +27,7 @@ cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ cflags-$(CONFIG_RISCV) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ -fpic cflags-$(CONFIG_LOONGARCH) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ - -fpic + -fpie cflags-$(CONFIG_EFI_GENERIC_STUB) += -I$(srctree)/scripts/dtc/libfdt
(Some explanation: -fpic does not only mean "generate position- independent code", but "generate position-independent code *suitable for use in a shared library*". On LoongArch -mdirect-extern-access cannot work for a shared library so the "-fpic -mdirect-extern-access" combination is rejected deliberately.) Not sure how to submit these changes properly... Do you prefer me to send V8 of this series or a single patch on top of your tree on GitHub?
-- Xi Ruoyao <xry111@xry111.site> School of Aerospace Science and Technology, Xidian University
| |