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.

Signed-off-by: Thomas Weißschuh linux@weissschuh.net --- Changes in v2: - Preserver 8-byte alignment of stack pointer - Link to v1: https://lore.kernel.org/r/20231108-nolibc-pic-v1-1-9b7a429d5a6d@weissschuh.n... --- tools/include/nolibc/arch-mips.h | 7 ++++++- tools/testing/selftests/nolibc/Makefile | 2 +- 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/include/nolibc/arch-mips.h b/tools/include/nolibc/arch-mips.h index 3a2c76716b83..62cc50ef3288 100644 --- a/tools/include/nolibc/arch-mips.h +++ b/tools/include/nolibc/arch-mips.h @@ -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 */ diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile index 508435b8ac2a..484bb02d8e6c 100644 --- a/tools/testing/selftests/nolibc/Makefile +++ b/tools/testing/selftests/nolibc/Makefile @@ -144,7 +144,7 @@ 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 \

--- base-commit: ba335752620565c25c3028fff9496bb8ef373602 change-id: 20770914-nolibc-pic-30043ffb0403

Best regards,