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>
LoongArch only support 32-bit/64-bit xchg/cmpxchg in native. But percpu
operation, qspinlock and some drivers need 8-bit/16-bit xchg/cmpxchg. We
add subword xchg/cmpxchg emulation in this patch because the emulation
has better performance than the generic implementation (on NUMA system),
and it can fix some build errors meanwhile [1].
LoongArch's guarantee for forward progress (avoid many ll/sc happening
at the same time and no one succeeds):
We have the "exclusive access (with timeout) of ll" feature to avoid
simultaneous ll (which also blocks other memory load/store on the same
address), and the "random delay of sc" feature to avoid simultaneous
sc. It is a mandatory requirement for multi-core LoongArch processors
to implement such features, only except those single-core and dual-core
processors (they also don't support multi-chip interconnection).
Feature bits are introduced in CPUCFG3, bit 3 and bit 4 [2].
[1] https://lore.kernel.org/loongarch/CAAhV-H6vvkuOzy8OemWdYK3taj5Jn3bFX0ZTwE=twM8ywpBUYA@mail.gmail.com/T/#t
[2] https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#_cpucfg
Reported-by: Sudip Mukherjee (Codethink) <sudipm.mukherjee@gmail.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rui Wang <wangrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
1, We assume arch/loongarch/include/asm/smp.h be included in include/
linux/smp.h is valid and the reverse inclusion isn't. So remove the
<linux/smp.h> in arch/loongarch/include/asm/smp.h.
2, arch/loongarch/include/asm/smp.h is only needed when CONFIG_SMP,
and setup.c include it only because it need plat_smp_setup(). So,
reorganize setup.c & smp.h, and then remove <asm/smp.h> in setup.c.
3, Fix cacheinfo.c and percpu.h build error by adding the missing header
files when !CONFIG_SMP.
4, Fix acpi.c build error by adding CONFIG_SMP guards.
5, Move irq_stat definition from smp.c to irq.c and fix its declaration.
6, Select CONFIG_SMP for CONFIG_NUMA, similar as other architectures do.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
LoongArch-based procesors have 4, 8 or 16 cores per package. This patch
adds multi-processor (SMP) support for LoongArch.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
