Commit 54410245 authored Nov 08, 2023 by Thomas Weißschuh

tools/nolibc: mips: add support for PIC

MIPS requires some extra instructions to set up the $gp register for the
with a pointer to the global data area.

This isn't needed for non-PIC builds, but this patch enables the code
unconditionally to prevent bitrot.

Also enable PIC in one of the test configurations for ongoing
validation.

Link: https://lore.kernel.org/r/20231108-nolibc-pic-v2-1-4fb0d6284757@weissschuh.net


Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

parent 8bcf9a48

tools/include/nolibc/arch-mips.h

+6 −1

Original line number	Diff line number	Diff line
		@@ -184,8 +184,13 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
		__asm__ volatile (
		".set push\n"
		".set noreorder\n"
		".option pic0\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 */

tools/testing/selftests/nolibc/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -147,7 +147,7 @@ CFLAGS_ppc = -m32 -mbig-endian -mno-vsx $(call cc-option,-mmultiple)
		CFLAGS_ppc64 = -m64 -mbig-endian -mno-vsx $(call cc-option,-mmultiple)
		CFLAGS_ppc64le = -m64 -mlittle-endian -mno-vsx $(call cc-option,-mabi=elfv2)
		CFLAGS_s390 = -m64
		CFLAGS_mips32le = -EL -mabi=32
		CFLAGS_mips32le = -EL -mabi=32 -fPIC
		CFLAGS_mips32be = -EB -mabi=32
		CFLAGS_STACKPROTECTOR ?= $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all))
		CFLAGS ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 -W -Wall -Wextra \