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RISC-V: Issue a local tlbflush if possible.

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In RISC-V, tlb flush happens via SBI which is expensive. If the local
cpu is the only cpu in cpumask, there is no need to invoke a SBI call.

Just do a local flush and return.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
This commit is contained in:
Atish Patra 2019-08-22 00:51:50 -07:00 committed by Paul Walmsley
parent 6384423f49
commit 31738ede9b
1 changed files with 17 additions and 2 deletions
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19
arch/riscv/mm/tlbflush.c
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@ -2,6 +2,7 @@
#include <linux/mm.h> #include <linux/mm.h>
#include <linux/smp.h> #include <linux/smp.h>
#include <linux/sched.h>
#include <asm/sbi.h> #include <asm/sbi.h>
void flush_tlb_all(void) void flush_tlb_all(void)
@ -9,16 +10,30 @@ void flush_tlb_all(void)
sbi_remote_sfence_vma(NULL, 0, -1); sbi_remote_sfence_vma(NULL, 0, -1);
} }
/*
* This function must not be called with cmask being null.
* Kernel may panic if cmask is NULL.
*/
static void __sbi_tlb_flush_range(struct cpumask *cmask, unsigned long start, static void __sbi_tlb_flush_range(struct cpumask *cmask, unsigned long start,
unsigned long size) unsigned long size)
{ {
struct cpumask hmask; struct cpumask hmask;
unsigned int cpuid;
if (cpumask_empty(cmask)) if (cpumask_empty(cmask))
return; return;
riscv_cpuid_to_hartid_mask(cmask, &hmask); cpuid = get_cpu();
sbi_remote_sfence_vma(hmask.bits, start, size);
if (cpumask_any_but(cmask, cpuid) >= nr_cpu_ids) {
/* local cpu is the only cpu present in cpumask */
local_flush_tlb_all();
} else {
riscv_cpuid_to_hartid_mask(cmask, &hmask);
sbi_remote_sfence_vma(cpumask_bits(&hmask), start, size);
}
put_cpu();
} }
void flush_tlb_mm(struct mm_struct *mm) void flush_tlb_mm(struct mm_struct *mm)