Unverified Commit 23311f57 authored by Nam Cao's avatar Nam Cao Committed by Palmer Dabbelt
Browse files

riscv: drop the use of XIP_OFFSET in XIP_FIXUP_FLASH_OFFSET 



XIP_OFFSET is the hard-coded offset of writable data section within the
kernel.

By hard-coding this value, the read-only section of the kernel (which is
placed before the writable data section) is restricted in size.

As a preparation to remove this hard-coded macro XIP_OFFSET entirely, stop
using XIP_OFFSET in XIP_FIXUP_FLASH_OFFSET. Instead, use __data_loc and
_sdata to do the same thing.

While at it, also add a description for XIP_FIXUP_FLASH_OFFSET.

Signed-off-by: default avatarNam Cao <namcao@linutronix.de>
Reviewed-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/7b3319657edd1822f3457e7e7c07aaa326cc2f87.1717789719.git.namcao@linutronix.de


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent e4eac34f

arch/riscv/include/asm/xip_fixup.h

+12 −4
Original line number Diff line number Diff line
@@ -24,13 +24,21 @@ 
	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_phys_offset: .dword CONFIG_XIP_PHYS_ADDR + XIP_OFFSET

#else

.macro XIP_FIXUP_OFFSET reg

.endm