Modify gnu-efi's _start to switch the stack. This allows us to not map memory regions which have EFI memory type EFI_BOOT_SERVICES_DATA, as the stack will be in the EFI_LOADER_CODE region instead. We'll still map the stack as R/W instead of R/X because we'll split the EFI_LOADER_CODE region on the _etext boundary and map addresses before _etext as R/X and the rest as R/W. Signed-off-by: Andrew Jones <andrew.jones@xxxxxxxxx> --- riscv/efi/crt0-efi-riscv64.S | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/riscv/efi/crt0-efi-riscv64.S b/riscv/efi/crt0-efi-riscv64.S index cc8551a43c6a..4ed82b14a1d6 100644 --- a/riscv/efi/crt0-efi-riscv64.S +++ b/riscv/efi/crt0-efi-riscv64.S @@ -164,7 +164,20 @@ _start: bne a0, zero, 0f ld a1, 8(sp) ld a0, 0(sp) + + /* Switch to our own stack */ + mv a2, sp + la sp, stacktop + mv fp, zero + push_fp zero + addi sp, sp, -16 + sd a2, 0(sp) + call efi_main + + /* Restore sp */ + ld sp, 0(sp) + ld ra, 16(sp) 0: addi sp, sp, 24 ret @@ -172,6 +185,11 @@ _start: // hand-craft a dummy .reloc section so EFI knows it's a relocatable executable: .data + +.balign 16384 +.space 16384 +stacktop: + dummy: .4byte 0 #define IMAGE_REL_ABSOLUTE 0 -- 2.44.0
