[PATCH 2/3] firmware: Replace sole uses of REGBYTES with __SIZEOF_LONG__

Jessica Clarke jrtc27 at jrtc27.com
Wed Jul 9 16:29:29 PDT 2025


This code has nothing to do with the ISA's registers, it's about the
format of ELF relocations. As such, __SIZEOF_LONG__, being a language /
ABI-level property, is a more appropriate constant to use. This also
makes it easier to support CHERI, where general-purpose registers are
extended to be capabilities, not just integers, and so the register size
is not the same as the machine word size. This also happens to make it
more correct for RV64ILP32, where the registers are 64-bit integers but
the ABI is 32-bit (both for long and for the ELF format), though
properly supporting that ABI is not part of the motivation here, just a
consequence of improving the code for CHERI.

Signed-off-by: Jessica Clarke <jrtc27 at jrtc27.com>
---
 firmware/fw_base.S | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/firmware/fw_base.S b/firmware/fw_base.S
index 2498797..aa8e264 100644
--- a/firmware/fw_base.S
+++ b/firmware/fw_base.S
@@ -80,17 +80,17 @@ _sc_fail:
 	lla	t1, __rel_dyn_end
 	beq	t0, t1, _relocate_done
 2:
-	REG_L	t5, REGBYTES(t0)	/* t5 <-- relocation info:type */
+	REG_L	t5, __SIZEOF_LONG__(t0)	/* t5 <-- relocation info:type */
 	li	t3, R_RISCV_RELATIVE	/* reloc type R_RISCV_RELATIVE */
 	bne	t5, t3, 3f
 	REG_L	t3, 0(t0)
-	REG_L	t5, (REGBYTES * 2)(t0)	/* t5 <-- addend */
+	REG_L	t5, (__SIZEOF_LONG__ * 2)(t0)	/* t5 <-- addend */
 	add	t5, t5, t2
 	add	t3, t3, t2
 	REG_S	t5, 0(t3)		/* store runtime address to the GOT entry */
 
 3:
-	addi	t0, t0, (REGBYTES * 3)
+	addi	t0, t0, (__SIZEOF_LONG__ * 3)
 	blt	t0, t1, 2b
 _relocate_done:
 	/* At this point we are running from link address */
-- 
2.34.1




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