firmware: Fix fw_rw_offset computation in fw_base.S

It seems BFD just does totally nonsensical things for SHN_ABS symbols
when producing position-independent outputs (both -pie and -shared)
for various historical reasons, and so SHN_ABS symbols are still
subject to relocation as far as BFD is concerned (except AArch64,
which fixes it in limited cases that don’t apply here...).

The above affects the _fw_rw_offset provided through fw_base.ldS
linker script which results in OpenSBI firmware failing to boot
when loaded at an address different from FW_TEXT_START.

Fixes: c10e3fe5f9a1 ("firmware: Add RW section offset in scratch")
Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>
Reported-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Tested-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>

diff --git a/firmware/fw_base.S b/firmware/fw_base.S
index e04b683..fb6ac92 100644 (file)
--- a/firmware/fw_base.S
+++ b/firmware/fw_base.S
@@ -526,7 +526,7 @@ _link_start:
 _link_end:
        RISCV_PTR       _fw_reloc_end
 __fw_rw_offset:
-       RISCV_PTR       _fw_rw_offset
+       RISCV_PTR       _fw_rw_start - _fw_start
 
        .section .entry, "ax", %progbits
        .align 3

diff --git a/firmware/fw_base.ldS b/firmware/fw_base.ldS
index 9a1304e..3d68484 100644 (file)
--- a/firmware/fw_base.ldS
+++ b/firmware/fw_base.ldS
@@ -64,7 +64,7 @@
        . = ALIGN(1 << LOG2CEIL((SIZEOF(.rodata) + SIZEOF(.text)
                                + SIZEOF(.dynsym) + SIZEOF(.rela.dyn))));
 
-       PROVIDE(_fw_rw_offset = (.  - _fw_start));
+       PROVIDE(_fw_rw_start = .);
 
        /* Beginning of the read-write data sections */