[PATCH v2 1/4] tools/nolibc: MIPS: drop $gp setup

From: Thomas Weißschuh
Date: Tue Feb 25 2025 - 12:19:25 EST


The setup of the global pointer "$gp" register was necessary when the C
entrypoint was called through "jal <symbol>".
However since commit 0daf8c86a451 ("tools/nolibc: mips: load current function to $t9")
"jalr" is used instead which does not require "$gp".

Remove the unnecessary $gp setup, simplifying the code and opening the
road for some other cleanups.

Suggested-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
Link: https://lore.kernel.org/lkml/alpine.DEB.2.21.2502172208570.65342@xxxxxxxxxxxxxxxxx/
Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
tools/include/nolibc/arch-mips.h | 6 ------
1 file changed, 6 deletions(-)

diff --git a/tools/include/nolibc/arch-mips.h b/tools/include/nolibc/arch-mips.h
index 753a8ed2cf695f0b5eac4b5e4d317fdb383ebf93..6d023d9f120301b2d6837c923c142ab2cf87ae5a 100644
--- a/tools/include/nolibc/arch-mips.h
+++ b/tools/include/nolibc/arch-mips.h
@@ -185,13 +185,7 @@ void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector __
__asm__ volatile (
".set push\n"
".set noreorder\n"
- "bal 1f\n" /* prime $ra for .cpload */
- "nop\n"
- "1:\n"
- ".cpload $ra\n"
"move $a0, $sp\n" /* save stack pointer to $a0, as arg1 of _start_c */
- "addiu $sp, $sp, -4\n" /* space for .cprestore to store $gp */
- ".cprestore 0\n"
"li $t0, -8\n"
"and $sp, $sp, $t0\n" /* $sp must be 8-byte aligned */
"addiu $sp, $sp, -16\n" /* the callee expects to save a0..a3 there */

--
2.48.1