From 6825c7a80f1863b975a00042abe140ea24813af2 Mon Sep 17 00:00:00 2001 From: Atish Patra Date: Tue, 2 Oct 2018 12:15:04 -0700 Subject: [PATCH] RISC-V: Add logical CPU indexing for RISC-V Currently, both Linux CPU id and hart id are same. This is not recommended as it will lead to discontinuous CPU indexing in Linux. Moreover, kdump kernel will run from CPU0 which would be absent if we follow existing scheme. Implement a logical mapping between Linux CPU id and hart id to decouple these two. Always mark the boot processor as CPU0 and all other CPUs get the logical CPU id based on their booting order. Signed-off-by: Atish Patra Reviewed-by: Anup Patel Reviewed-by: Christoph Hellwig Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/smp.h | 24 +++++++++++++++++++++++- arch/riscv/kernel/setup.c | 4 ++++ arch/riscv/kernel/smp.c | 19 +++++++++++++++++++ 3 files changed, 46 insertions(+), 1 deletion(-) diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h index 85d7619eb927..47fd61dfc897 100644 --- a/arch/riscv/include/asm/smp.h +++ b/arch/riscv/include/asm/smp.h @@ -18,6 +18,13 @@ #include #include +#define INVALID_HARTID ULONG_MAX +/* + * Mapping between linux logical cpu index and hartid. + */ +extern unsigned long __cpuid_to_hartid_map[NR_CPUS]; +#define cpuid_to_hartid_map(cpu) __cpuid_to_hartid_map[cpu] + #ifdef CONFIG_SMP /* SMP initialization hook for setup_arch */ @@ -29,12 +36,27 @@ void arch_send_call_function_ipi_mask(struct cpumask *mask); /* Hook for the generic smp_call_function_single() routine. */ void arch_send_call_function_single_ipi(int cpu); +int riscv_hartid_to_cpuid(int hartid); +void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out); + /* * Obtains the hart ID of the currently executing task. This relies on * THREAD_INFO_IN_TASK, but we define that unconditionally. */ #define raw_smp_processor_id() (current_thread_info()->cpu) -#endif /* CONFIG_SMP */ +#else + +static inline int riscv_hartid_to_cpuid(int hartid) +{ + return 0; +} +static inline void riscv_cpuid_to_hartid_mask(const struct cpumask *in, + struct cpumask *out) +{ + cpumask_set_cpu(cpuid_to_hartid_map(0), out); +} + +#endif /* CONFIG_SMP */ #endif /* _ASM_RISCV_SMP_H */ diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c index b2d26d9d8489..d5d8611066d5 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -82,6 +82,10 @@ EXPORT_SYMBOL(empty_zero_page); /* The lucky hart to first increment this variable will boot the other cores */ atomic_t hart_lottery; +unsigned long __cpuid_to_hartid_map[NR_CPUS] = { + [0 ... NR_CPUS-1] = INVALID_HARTID +}; + #ifdef CONFIG_BLK_DEV_INITRD static void __init setup_initrd(void) { diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c index 906fe21ea21b..0bd48935f886 100644 --- a/arch/riscv/kernel/smp.c +++ b/arch/riscv/kernel/smp.c @@ -38,7 +38,26 @@ enum ipi_message_type { IPI_MAX }; +int riscv_hartid_to_cpuid(int hartid) +{ + int i = -1; + + for (i = 0; i < NR_CPUS; i++) + if (cpuid_to_hartid_map(i) == hartid) + return i; + + pr_err("Couldn't find cpu id for hartid [%d]\n", hartid); + BUG(); + return i; +} +void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out) +{ + int cpu; + + for_each_cpu(cpu, in) + cpumask_set_cpu(cpuid_to_hartid_map(cpu), out); +} /* Unsupported */ int setup_profiling_timer(unsigned int multiplier) { -- 2.30.2