On 12.01.24 19:56, Palmer Dabbelt wrote: > On Fri, 12 Jan 2024 10:51:16 PST (-0800), Ard Biesheuvel wrote: >> Hi Jan, >> >> On Fri, 12 Jan 2024 at 19:37, Jan Kiszka <jan.kiszka@xxxxxxxxxxx> wrote: >>> >>> From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> >>> >>> The cflags for the RISC-V efistub were missing -mno-relax, thus were >>> under the risk that the compiler could use GP-relative addressing. That >>> happened for _edata with binutils-2.41 and kernel 6.1, causing the >>> relocation to fail due to an invalid kernel_size in handle_kernel_image. >>> It was not yet observed with newer versions, but that may just be luck. >>> >>> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> >>> --- >>> >>> Something like this should go to stable as well, but we will need >>> rebased patches. >>> >>> drivers/firmware/efi/libstub/Makefile | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/firmware/efi/libstub/Makefile >>> b/drivers/firmware/efi/libstub/Makefile >>> index 06964a3c130f..d561d7de46a9 100644 >>> --- a/drivers/firmware/efi/libstub/Makefile >>> +++ b/drivers/firmware/efi/libstub/Makefile >>> @@ -28,7 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN >>> -DEFI_HAVE_STRNLEN \ >>> -DEFI_HAVE_MEMCHR >>> -DEFI_HAVE_STRRCHR \ >>> -DEFI_HAVE_STRCMP -fno-builtin >>> -fpic \ >>> $(call >>> cc-option,-mno-single-pic-base) >>> -cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE >>> +cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax >> >> Can we detect the presence of these references (via the relocation >> type)? We already do something similar for ordinary absolute >> references too. > > If there's no `__global_pointer$` symbol then the linker won't make > GP-relative relaxations (because it doesn't know where GP is). We > usually define that symbol in the linker script, but I'm not entierly > sure how libstub gets its linker script... > The stub seems to be linked together with the rest of the kernel, thus the regular arch/riscv/kernel/vmlinux.lds.S is used. Jan -- Siemens AG, Technology Linux Expert Center
