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LoongArch: Add multi-processor (SMP) support
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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>
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chenhuacai committed Jun 3, 2022
1 parent c6b99be commit 46859ac
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Showing 27 changed files with 1,550 additions and 10 deletions.
40 changes: 39 additions & 1 deletion arch/loongarch/Kconfig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@ config LOONGARCH
select GENERIC_LIB_UCMPDI2
select GENERIC_PCI_IOMAP
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select GENERIC_TIME_VSYSCALL
select GPIOLIB
select HAVE_ARCH_AUDITSYSCALL
Expand Down Expand Up @@ -92,7 +93,7 @@ config LOONGARCH
select HAVE_RSEQ
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_TIF_NOHZ
select HAVE_VIRT_CPU_ACCOUNTING_GEN
select HAVE_VIRT_CPU_ACCOUNTING_GEN if !SMP
select IRQ_FORCED_THREADING
select IRQ_LOONGARCH_CPU
select MODULES_USE_ELF_RELA if MODULES
Expand Down Expand Up @@ -297,6 +298,43 @@ config EFI
This enables the kernel to use EFI runtime services that are
available (such as the EFI variable services).

config SMP
bool "Multi-Processing support"
help
This enables support for systems with more than one CPU. If you have
a system with only one CPU, say N. If you have a system with more
than one CPU, say Y.

If you say N here, the kernel will run on uni- and multiprocessor
machines, but will use only one CPU of a multiprocessor machine. If
you say Y here, the kernel will run on many, but not all,
uniprocessor machines. On a uniprocessor machine, the kernel
will run faster if you say N here.

See also the SMP-HOWTO available at <http://www.tldp.org/docs.html#howto>.

If you don't know what to do here, say N.

config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
depends on SMP
select GENERIC_IRQ_MIGRATION
help
Say Y here to allow turning CPUs off and on. CPUs can be
controlled through /sys/devices/system/cpu.
(Note: power management support will enable this option
automatically on SMP systems. )
Say N if you want to disable CPU hotplug.

config NR_CPUS
int "Maximum number of CPUs (2-256)"
range 2 256
depends on SMP
default "64"
help
This allows you to specify the maximum number of CPUs which this
kernel will support.

config FORCE_MAX_ZONEORDER
int "Maximum zone order"
range 14 64 if PAGE_SIZE_64KB
Expand Down
4 changes: 4 additions & 0 deletions arch/loongarch/include/asm/atomic.h
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Original file line number Diff line number Diff line change
Expand Up @@ -162,6 +162,7 @@ static inline int arch_atomic_sub_if_positive(int i, atomic_t *v)
" sc.w %1, %2 \n"
" beq $zero, %1, 1b \n"
"2: \n"
__WEAK_LLSC_MB
: "=&r" (result), "=&r" (temp),
"+" GCC_OFF_SMALL_ASM() (v->counter)
: "I" (-i));
Expand All @@ -174,6 +175,7 @@ static inline int arch_atomic_sub_if_positive(int i, atomic_t *v)
" sc.w %1, %2 \n"
" beq $zero, %1, 1b \n"
"2: \n"
__WEAK_LLSC_MB
: "=&r" (result), "=&r" (temp),
"+" GCC_OFF_SMALL_ASM() (v->counter)
: "r" (i));
Expand Down Expand Up @@ -323,6 +325,7 @@ static inline long arch_atomic64_sub_if_positive(long i, atomic64_t *v)
" sc.d %1, %2 \n"
" beq %1, $zero, 1b \n"
"2: \n"
__WEAK_LLSC_MB
: "=&r" (result), "=&r" (temp),
"+" GCC_OFF_SMALL_ASM() (v->counter)
: "I" (-i));
Expand All @@ -335,6 +338,7 @@ static inline long arch_atomic64_sub_if_positive(long i, atomic64_t *v)
" sc.d %1, %2 \n"
" beq %1, $zero, 1b \n"
"2: \n"
__WEAK_LLSC_MB
: "=&r" (result), "=&r" (temp),
"+" GCC_OFF_SMALL_ASM() (v->counter)
: "r" (i));
Expand Down
108 changes: 108 additions & 0 deletions arch/loongarch/include/asm/barrier.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,19 @@
#define mb() fast_mb()
#define iob() fast_iob()

#define __smp_mb() __asm__ __volatile__("dbar 0" : : : "memory")
#define __smp_rmb() __asm__ __volatile__("dbar 0" : : : "memory")
#define __smp_wmb() __asm__ __volatile__("dbar 0" : : : "memory")

#ifdef CONFIG_SMP
#define __WEAK_LLSC_MB " dbar 0 \n"
#else
#define __WEAK_LLSC_MB " \n"
#endif

#define __smp_mb__before_atomic() barrier()
#define __smp_mb__after_atomic() barrier()

/**
* array_index_mask_nospec() - generate a ~0 mask when index < size, 0 otherwise
* @index: array element index
Expand Down Expand Up @@ -46,6 +59,101 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
return mask;
}

#define __smp_load_acquire(p) \
({ \
union { typeof(*p) __val; char __c[1]; } __u; \
unsigned long __tmp = 0; \
compiletime_assert_atomic_type(*p); \
switch (sizeof(*p)) { \
case 1: \
*(__u8 *)__u.__c = *(volatile __u8 *)p; \
__smp_mb(); \
break; \
case 2: \
*(__u16 *)__u.__c = *(volatile __u16 *)p; \
__smp_mb(); \
break; \
case 4: \
__asm__ __volatile__( \
"amor_db.w %[val], %[tmp], %[mem] \n" \
: [val] "=&r" (*(__u32 *)__u.__c) \
: [mem] "ZB" (*(u32 *) p), [tmp] "r" (__tmp) \
: "memory"); \
break; \
case 8: \
__asm__ __volatile__( \
"amor_db.d %[val], %[tmp], %[mem] \n" \
: [val] "=&r" (*(__u64 *)__u.__c) \
: [mem] "ZB" (*(u64 *) p), [tmp] "r" (__tmp) \
: "memory"); \
break; \
} \
(typeof(*p))__u.__val; \
})

#define __smp_store_release(p, v) \
do { \
union { typeof(*p) __val; char __c[1]; } __u = \
{ .__val = (__force typeof(*p)) (v) }; \
unsigned long __tmp; \
compiletime_assert_atomic_type(*p); \
switch (sizeof(*p)) { \
case 1: \
__smp_mb(); \
*(volatile __u8 *)p = *(__u8 *)__u.__c; \
break; \
case 2: \
__smp_mb(); \
*(volatile __u16 *)p = *(__u16 *)__u.__c; \
break; \
case 4: \
__asm__ __volatile__( \
"amswap_db.w %[tmp], %[val], %[mem] \n" \
: [mem] "+ZB" (*(u32 *)p), [tmp] "=&r" (__tmp) \
: [val] "r" (*(__u32 *)__u.__c) \
: ); \
break; \
case 8: \
__asm__ __volatile__( \
"amswap_db.d %[tmp], %[val], %[mem] \n" \
: [mem] "+ZB" (*(u64 *)p), [tmp] "=&r" (__tmp) \
: [val] "r" (*(__u64 *)__u.__c) \
: ); \
break; \
} \
} while (0)

#define __smp_store_mb(p, v) \
do { \
union { typeof(p) __val; char __c[1]; } __u = \
{ .__val = (__force typeof(p)) (v) }; \
unsigned long __tmp; \
switch (sizeof(p)) { \
case 1: \
*(volatile __u8 *)&p = *(__u8 *)__u.__c; \
__smp_mb(); \
break; \
case 2: \
*(volatile __u16 *)&p = *(__u16 *)__u.__c; \
__smp_mb(); \
break; \
case 4: \
__asm__ __volatile__( \
"amswap_db.w %[tmp], %[val], %[mem] \n" \
: [mem] "+ZB" (*(u32 *)&p), [tmp] "=&r" (__tmp) \
: [val] "r" (*(__u32 *)__u.__c) \
: ); \
break; \
case 8: \
__asm__ __volatile__( \
"amswap_db.d %[tmp], %[val], %[mem] \n" \
: [mem] "+ZB" (*(u64 *)&p), [tmp] "=&r" (__tmp) \
: [val] "r" (*(__u64 *)__u.__c) \
: ); \
break; \
} \
} while (0)

#include <asm-generic/barrier.h>

#endif /* __ASM_BARRIER_H */
1 change: 1 addition & 0 deletions arch/loongarch/include/asm/cmpxchg.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@ static inline unsigned long __xchg(volatile void *ptr, unsigned long x,
" " st " $t0, %1 \n" \
" beq $zero, $t0, 1b \n" \
"2: \n" \
__WEAK_LLSC_MB \
: "=&r" (__ret), "=ZB"(*m) \
: "ZB"(*m), "Jr" (old), "Jr" (new) \
: "t0", "memory"); \
Expand Down
1 change: 1 addition & 0 deletions arch/loongarch/include/asm/futex.h
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval, u32 newv
"2: sc.w $t0, %2 \n"
" beq $zero, $t0, 1b \n"
"3: \n"
__WEAK_LLSC_MB
" .section .fixup,\"ax\" \n"
"4: li.d %0, %6 \n"
" b 3b \n"
Expand Down
2 changes: 2 additions & 0 deletions arch/loongarch/include/asm/hardirq.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,4 +21,6 @@ typedef struct {

DECLARE_PER_CPU_ALIGNED(irq_cpustat_t, irq_stat);

#define __ARCH_IRQ_STAT

#endif /* _ASM_HARDIRQ_H */
2 changes: 2 additions & 0 deletions arch/loongarch/include/asm/irq.h
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Original file line number Diff line number Diff line change
Expand Up @@ -125,6 +125,8 @@ extern struct irq_domain *pch_lpc_domain;
extern struct irq_domain *pch_msi_domain[MAX_IO_PICS];
extern struct irq_domain *pch_pic_domain[MAX_IO_PICS];

extern irqreturn_t loongson3_ipi_interrupt(int irq, void *dev);

#include <asm-generic/irq.h>

#endif /* _ASM_IRQ_H */
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