diff options
Diffstat (limited to 'arch/riscv/include/asm/xip_fixup.h')
| -rw-r--r-- | arch/riscv/include/asm/xip_fixup.h | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/arch/riscv/include/asm/xip_fixup.h b/arch/riscv/include/asm/xip_fixup.h index b65bf6306f69..f3d56299bc22 100644 --- a/arch/riscv/include/asm/xip_fixup.h +++ b/arch/riscv/include/asm/xip_fixup.h @@ -9,18 +9,36 @@ #ifdef CONFIG_XIP_KERNEL .macro XIP_FIXUP_OFFSET reg - REG_L t0, _xip_fixup + /* Fix-up address in Flash into address in RAM early during boot before + * MMU is up. Because generated code "thinks" data is in Flash, but it + * is actually in RAM (actually data is also in Flash, but Flash is + * read-only, thus we need to use the data residing in RAM). + * + * The start of data in Flash is _sdata and the start of data in RAM is + * CONFIG_PHYS_RAM_BASE. So this fix-up essentially does this: + * reg += CONFIG_PHYS_RAM_BASE - _start + */ + li t0, CONFIG_PHYS_RAM_BASE add \reg, \reg, t0 + la t0, _sdata + sub \reg, \reg, t0 .endm .macro XIP_FIXUP_FLASH_OFFSET reg + /* In linker script, at the transition from read-only section to + * writable section, the VMA is increased while LMA remains the same. + * (See in linker script how _sdata, __data_loc and LOAD_OFFSET is + * changed) + * + * Consequently, early during boot before MMU is up, the generated code + * reads the "writable" section at wrong addresses, because VMA is used + * by compiler to generate code, but the data is located in Flash using + * LMA. + */ + la t0, _sdata + sub \reg, \reg, t0 la t0, __data_loc - REG_L t1, _xip_phys_offset - sub \reg, \reg, t1 add \reg, \reg, t0 .endm - -_xip_fixup: .dword CONFIG_PHYS_RAM_BASE - CONFIG_XIP_PHYS_ADDR - XIP_OFFSET -_xip_phys_offset: .dword CONFIG_XIP_PHYS_ADDR + XIP_OFFSET #else .macro XIP_FIXUP_OFFSET reg .endm |