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powerpc/64s/hash: Use POWER9 SLBIA IH=3 variant in switch_slb 

POWER9 introduces SLBIA IH=3, which invalidates all SLB entries and
associated lookaside information that have a class value of 1, which
Linux assigns to user addresses. This matches what switch_slb wants,
and allows a simple fast implementation that avoids the slb_cache
complexity.

As a side-effect, the POWER5 < DD2.1 SLB invalidation workaround is
also avoided on POWER9.

Process context switching rate is improved about 2.2% for a small
process that hits the slb cache which is the best case for the current
code.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2018-09-15 01:30:50 +10:00 committed by Michael Ellerman
parent 5141c182d7
commit 82d8f4c22f
2 changed files with 55 additions and 39 deletions
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83
arch/powerpc/mm/slb.c
View File

@ -279,7 +279,6 @@ static inline int esids_match(unsigned long addr1, unsigned long addr2)
/* Flush all user entries from the segment table of the current processor. */
void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
{
unsigned long offset;
unsigned long pc = KSTK_EIP(tsk);
unsigned long stack = KSTK_ESP(tsk);
unsigned long exec_base;
@ -291,45 +290,56 @@ void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
* which would update the slb_cache/slb_cache_ptr fields in the PACA.
*/
hard_irq_disable();
offset = get_paca()->slb_cache_ptr;
if (!mmu_has_feature(MMU_FTR_NO_SLBIE_B) &&
offset <= SLB_CACHE_ENTRIES) {
unsigned long slbie_data = 0;
int i;
if (cpu_has_feature(CPU_FTR_ARCH_300)) {
/*
* SLBIA IH=3 invalidates all Class=1 SLBEs and their
* associated lookaside structures, which matches what
* switch_slb wants. So ARCH_300 does not use the slb
* cache.
*/
asm volatile("isync ; " PPC_SLBIA(3)" ; isync");
} else {
unsigned long offset = get_paca()->slb_cache_ptr;
asm volatile("isync" : : : "memory");
for (i = 0; i < offset; i++) {
slbie_data = (unsigned long)get_paca()->slb_cache[i]
<< SID_SHIFT; /* EA */
slbie_data |= user_segment_size(slbie_data)
<< SLBIE_SSIZE_SHIFT;
slbie_data |= SLBIE_C; /* C set for user addresses */
asm volatile("slbie %0" : : "r" (slbie_data));
if (!mmu_has_feature(MMU_FTR_NO_SLBIE_B) &&
offset <= SLB_CACHE_ENTRIES) {
unsigned long slbie_data = 0;
int i;
asm volatile("isync" : : : "memory");
for (i = 0; i < offset; i++) {
/* EA */
slbie_data = (unsigned long)
get_paca()->slb_cache[i] << SID_SHIFT;
slbie_data |= user_segment_size(slbie_data)
<< SLBIE_SSIZE_SHIFT;
slbie_data |= SLBIE_C; /* user slbs have C=1 */
asm volatile("slbie %0" : : "r" (slbie_data));
}
/* Workaround POWER5 < DD2.1 issue */
if (!cpu_has_feature(CPU_FTR_ARCH_207S) && offset == 1)
asm volatile("slbie %0" : : "r" (slbie_data));
asm volatile("isync" : : : "memory");
} else {
struct slb_shadow *p = get_slb_shadow();
unsigned long ksp_esid_data =
be64_to_cpu(p->save_area[KSTACK_INDEX].esid);
unsigned long ksp_vsid_data =
be64_to_cpu(p->save_area[KSTACK_INDEX].vsid);
asm volatile("isync\n"
PPC_SLBIA(1) "\n"
"slbmte %0,%1\n"
"isync"
:: "r"(ksp_vsid_data),
"r"(ksp_esid_data));
}
/* Workaround POWER5 < DD2.1 issue */
if (!cpu_has_feature(CPU_FTR_ARCH_207S) && offset == 1)
asm volatile("slbie %0" : : "r" (slbie_data));
asm volatile("isync" : : : "memory");
} else {
struct slb_shadow *p = get_slb_shadow();
unsigned long ksp_esid_data =
be64_to_cpu(p->save_area[KSTACK_INDEX].esid);
unsigned long ksp_vsid_data =
be64_to_cpu(p->save_area[KSTACK_INDEX].vsid);
asm volatile("isync\n"
PPC_SLBIA(1) "\n"
"slbmte %0,%1\n"
"isync"
:: "r"(ksp_vsid_data),
"r"(ksp_esid_data));
asm volatile("isync" : : : "memory");
get_paca()->slb_cache_ptr = 0;
}
get_paca()->slb_cache_ptr = 0;
copy_mm_to_paca(mm);
/*
@ -455,6 +465,9 @@ static void insert_slb_entry(unsigned long vsid, unsigned long ea,
enum slb_index index;
int slb_cache_index;
if (cpu_has_feature(CPU_FTR_ARCH_300))
return; /* ISAv3.0B and later does not use slb_cache */
/*
* We are irq disabled, hence should be safe to access PACA.
*/

11
arch/powerpc/xmon/xmon.c
View File

@ -2393,10 +2393,13 @@ static void dump_one_paca(int cpu)
}
}
DUMP(p, vmalloc_sllp, "%#-*x");
DUMP(p, slb_cache_ptr, "%#-*x");
for (i = 0; i < SLB_CACHE_ENTRIES; i++)
printf(" %-*s[%d] = 0x%016x\n",
22, "slb_cache", i, p->slb_cache[i]);
if (!early_cpu_has_feature(CPU_FTR_ARCH_300)) {
DUMP(p, slb_cache_ptr, "%#-*x");
for (i = 0; i < SLB_CACHE_ENTRIES; i++)
printf(" %-*s[%d] = 0x%016x\n",
22, "slb_cache", i, p->slb_cache[i]);
}
DUMP(p, rfi_flush_fallback_area, "%-*px");
#endif