TOC relocations are like GOT relocations on other architectures. However, unlike other architectures, GNU ld's ppc64 port defines .TOC. relative to the .got output section instead of the linker synthesized .got input section. LLD defines .TOC. as the .got input section plus 0x8000. When CONFIG_PPC_OF_BOOT_TRAMPOLINE=y, arch/powerpc/kernel/prom_init.o is built, and LLD computed .TOC. can be different from __toc_start defined by the linker script.
Simplify kernel_toc_addr with asm label .TOC. so that we can get rid of __toc_start. With this change, powernv_defconfig with CONFIG_PPC_OF_BOOT_TRAMPOLINE=y is bootable with LLD. There is still an untriaged issue with Alexey's configuration. Link: https://github.com/ClangBuiltLinux/linux/issues/1318 Reported-by: Alexey Kardashevskiy <a...@ozlabs.ru> Signed-off-by: Fangrui Song <mask...@google.com> --- arch/powerpc/boot/crt0.S | 2 +- arch/powerpc/boot/zImage.lds.S | 1 - arch/powerpc/include/asm/sections.h | 10 ++-------- arch/powerpc/kernel/head_64.S | 2 +- arch/powerpc/kernel/vmlinux.lds.S | 1 - 5 files changed, 4 insertions(+), 12 deletions(-) diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S index 1d83966f5ef6..e45907fe468f 100644 --- a/arch/powerpc/boot/crt0.S +++ b/arch/powerpc/boot/crt0.S @@ -28,7 +28,7 @@ p_etext: .8byte _etext p_bss_start: .8byte __bss_start p_end: .8byte _end -p_toc: .8byte __toc_start + 0x8000 - p_base +p_toc: .8byte .TOC. - p_base p_dyn: .8byte __dynamic_start - p_base p_rela: .8byte __rela_dyn_start - p_base p_prom: .8byte 0 diff --git a/arch/powerpc/boot/zImage.lds.S b/arch/powerpc/boot/zImage.lds.S index d6f072865627..32cf7816292f 100644 --- a/arch/powerpc/boot/zImage.lds.S +++ b/arch/powerpc/boot/zImage.lds.S @@ -39,7 +39,6 @@ SECTIONS . = ALIGN(256); .got : { - __toc_start = .; *(.got) *(.toc) } diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h index 324d7b298ec3..bd22ca0b5eca 100644 --- a/arch/powerpc/include/asm/sections.h +++ b/arch/powerpc/include/asm/sections.h @@ -48,14 +48,8 @@ static inline int in_kernel_text(unsigned long addr) static inline unsigned long kernel_toc_addr(void) { - /* Defined by the linker, see vmlinux.lds.S */ - extern unsigned long __toc_start; - - /* - * The TOC register (r2) points 32kB into the TOC, so that 64kB of - * the TOC can be addressed using a single machine instruction. - */ - return (unsigned long)(&__toc_start) + 0x8000UL; + extern unsigned long toc asm(".TOC."); + return (unsigned long)(&toc); } static inline int overlaps_interrupt_vector_text(unsigned long start, diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index ece7f97bafff..9542d03b2efe 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -899,7 +899,7 @@ _GLOBAL(relative_toc) blr .balign 8 -p_toc: .8byte __toc_start + 0x8000 - 0b +p_toc: .8byte .TOC. - 0b /* * This is where the main kernel code starts. diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 72fa3c00229a..c28f4e5bae3f 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -328,7 +328,6 @@ SECTIONS . = ALIGN(256); .got : AT(ADDR(.got) - LOAD_OFFSET) { - __toc_start = .; #ifndef CONFIG_RELOCATABLE __prom_init_toc_start = .; arch/powerpc/kernel/prom_init.o*(.toc .got) -- 2.30.1.766.gb4fecdf3b7-goog
