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11cd8a6483
If explicit relocation hints are used by the toolchain, -Wa,-mla-*
options will be useless for the C code. So only use them for the
!CONFIG_AS_HAS_EXPLICIT_RELOCS case.
Replace "la" with "la.pcrel" in head.S to keep the semantic consistent
with new and old toolchains for the low level startup code.
For per-CPU variables, the "address" of the symbol is actually an offset
from $r21. The value is near the loading address of main kernel image,
but far from the loading address of modules. So we use model("extreme")
attibute to tell the compiler that a PC-relative addressing with 32-bit
offset is not sufficient for local per-CPU variables.
The behavior with different assemblers and compilers are summarized in
the following table:
AS has CC has
explicit relocs explicit relocs * Behavior
==============================================================
No No Use la.* macros.
No change from Linux 6.0.
--------------------------------------------------------------
No Yes Disable explicit relocs.
No change from Linux 6.0.
--------------------------------------------------------------
Yes No Not supported.
--------------------------------------------------------------
Yes Yes Enable explicit relocs.
No -Wa,-mla* options used.
==============================================================
*: We assume CC must have model attribute if it has explicit relocs.
Both features are added in GCC 13 development cycle, so any GCC
release >= 13 should be OK. Using early GCC 13 development snapshots
may produce modules with unsupported relocations.
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=f09482a
Link: https://gcc.gnu.org/r13-1834
Link: https://gcc.gnu.org/r13-2199
Tested-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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| .. | ||
| .gitignore | ||
| access-helper.h | ||
| acpi.c | ||
| asm-offsets.c | ||
| cacheinfo.c | ||
| cpu-probe.c | ||
| dma.c | ||
| efi-header.S | ||
| efi.c | ||
| elf.c | ||
| entry.S | ||
| env.c | ||
| fpu.S | ||
| genex.S | ||
| head.S | ||
| idle.c | ||
| image-vars.h | ||
| inst.c | ||
| io.c | ||
| irq.c | ||
| Makefile | ||
| mem.c | ||
| module-sections.c | ||
| module.c | ||
| numa.c | ||
| proc.c | ||
| process.c | ||
| ptrace.c | ||
| reset.c | ||
| setup.c | ||
| signal.c | ||
| smp.c | ||
| stacktrace.c | ||
| switch.S | ||
| syscall.c | ||
| time.c | ||
| topology.c | ||
| traps.c | ||
| unwind_guess.c | ||
| unwind_prologue.c | ||
| vdso.c | ||
| vmlinux.lds.S | ||