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-rw-r--r--arch/powerpc/include/asm/processor.h1
-rw-r--r--arch/powerpc/include/asm/thread_info.h5
-rw-r--r--arch/powerpc/kernel/process.c7
-rw-r--r--arch/powerpc/mm/mmu_context_book3s64.c4
-rw-r--r--arch/powerpc/mm/slb.c164
5 files changed, 142 insertions, 39 deletions
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 52fadded5c1e..350c584ca179 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -273,6 +273,7 @@ struct thread_struct {
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
struct arch_hw_breakpoint hw_brk; /* info on the hardware breakpoint */
unsigned long trap_nr; /* last trap # on this thread */
+ u8 load_slb; /* Ages out SLB preload cache entries */
u8 load_fp;
#ifdef CONFIG_ALTIVEC
u8 load_vec;
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index f9a442bb5a72..406eb952b808 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -29,6 +29,7 @@
#include <asm/page.h>
#include <asm/accounting.h>
+#define SLB_PRELOAD_NR 16U
/*
* low level task data.
*/
@@ -44,6 +45,10 @@ struct thread_info {
#if defined(CONFIG_VIRT_CPU_ACCOUNTING_NATIVE) && defined(CONFIG_PPC32)
struct cpu_accounting_data accounting;
#endif
+ u8 slb_preload_nr;
+ u8 slb_preload_tail;
+ u32 slb_preload_esid[SLB_PRELOAD_NR];
+
/* low level flags - has atomic operations done on it */
unsigned long flags ____cacheline_aligned_in_smp;
};
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index e4feb45ae4c6..03c2e1f134bc 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1719,6 +1719,8 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
return 0;
}
+void preload_new_slb_context(unsigned long start, unsigned long sp);
+
/*
* Set up a thread for executing a new program
*/
@@ -1726,6 +1728,10 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
{
#ifdef CONFIG_PPC64
unsigned long load_addr = regs->gpr[2]; /* saved by ELF_PLAT_INIT */
+
+#ifdef CONFIG_PPC_BOOK3S_64
+ preload_new_slb_context(start, sp);
+#endif
#endif
/*
@@ -1816,6 +1822,7 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
#ifdef CONFIG_VSX
current->thread.used_vsr = 0;
#endif
+ current->thread.load_slb = 0;
current->thread.load_fp = 0;
memset(&current->thread.fp_state, 0, sizeof(current->thread.fp_state));
current->thread.fp_save_area = NULL;
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c
index f7352c66b6b8..510f103d7813 100644
--- a/arch/powerpc/mm/mmu_context_book3s64.c
+++ b/arch/powerpc/mm/mmu_context_book3s64.c
@@ -53,6 +53,8 @@ int hash__alloc_context_id(void)
}
EXPORT_SYMBOL_GPL(hash__alloc_context_id);
+void slb_setup_new_exec(void);
+
static int hash__init_new_context(struct mm_struct *mm)
{
int index;
@@ -87,6 +89,8 @@ static int hash__init_new_context(struct mm_struct *mm)
void hash__setup_new_exec(void)
{
slice_setup_new_exec();
+
+ slb_setup_new_exec();
}
static int radix__init_new_context(struct mm_struct *mm)
diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 5bfbd3f61312..b438220c4336 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -257,41 +257,119 @@ void slb_vmalloc_update(void)
slb_flush_and_rebolt();
}
-/* Helper function to compare esids. There are four cases to handle.
- * 1. The system is not 1T segment size capable. Use the GET_ESID compare.
- * 2. The system is 1T capable, both addresses are < 1T, use the GET_ESID compare.
- * 3. The system is 1T capable, only one of the two addresses is > 1T. This is not a match.
- * 4. The system is 1T capable, both addresses are > 1T, use the GET_ESID_1T macro to compare.
- */
-static inline int esids_match(unsigned long addr1, unsigned long addr2)
+static bool preload_hit(struct thread_info *ti, unsigned long esid)
{
- int esid_1t_count;
+ u8 i;
- /* System is not 1T segment size capable. */
- if (!mmu_has_feature(MMU_FTR_1T_SEGMENT))
- return (GET_ESID(addr1) == GET_ESID(addr2));
+ for (i = 0; i < ti->slb_preload_nr; i++) {
+ u8 idx;
+
+ idx = (ti->slb_preload_tail + i) % SLB_PRELOAD_NR;
+ if (esid == ti->slb_preload_esid[idx])
+ return true;
+ }
+ return false;
+}
+
+static bool preload_add(struct thread_info *ti, unsigned long ea)
+{
+ unsigned long esid;
+ u8 idx;
+
+ if (mmu_has_feature(MMU_FTR_1T_SEGMENT)) {
+ /* EAs are stored >> 28 so 256MB segments don't need clearing */
+ if (ea & ESID_MASK_1T)
+ ea &= ESID_MASK_1T;
+ }
- esid_1t_count = (((addr1 >> SID_SHIFT_1T) != 0) +
- ((addr2 >> SID_SHIFT_1T) != 0));
+ esid = ea >> SID_SHIFT;
- /* both addresses are < 1T */
- if (esid_1t_count == 0)
- return (GET_ESID(addr1) == GET_ESID(addr2));
+ if (preload_hit(ti, esid))
+ return false;
- /* One address < 1T, the other > 1T. Not a match */
- if (esid_1t_count == 1)
- return 0;
+ idx = (ti->slb_preload_tail + ti->slb_preload_nr) % SLB_PRELOAD_NR;
+ ti->slb_preload_esid[idx] = esid;
+ if (ti->slb_preload_nr == SLB_PRELOAD_NR)
+ ti->slb_preload_tail = (ti->slb_preload_tail + 1) % SLB_PRELOAD_NR;
+ else
+ ti->slb_preload_nr++;
- /* Both addresses are > 1T. */
- return (GET_ESID_1T(addr1) == GET_ESID_1T(addr2));
+ return true;
}
+static void preload_age(struct thread_info *ti)
+{
+ if (!ti->slb_preload_nr)
+ return;
+ ti->slb_preload_nr--;
+ ti->slb_preload_tail = (ti->slb_preload_tail + 1) % SLB_PRELOAD_NR;
+}
+
+void slb_setup_new_exec(void)
+{
+ struct thread_info *ti = current_thread_info();
+ struct mm_struct *mm = current->mm;
+ unsigned long exec = 0x10000000;
+
+ /*
+ * We have no good place to clear the slb preload cache on exec,
+ * flush_thread is about the earliest arch hook but that happens
+ * after we switch to the mm and have aleady preloaded the SLBEs.
+ *
+ * For the most part that's probably okay to use entries from the
+ * previous exec, they will age out if unused. It may turn out to
+ * be an advantage to clear the cache before switching to it,
+ * however.
+ */
+
+ /*
+ * preload some userspace segments into the SLB.
+ * Almost all 32 and 64bit PowerPC executables are linked at
+ * 0x10000000 so it makes sense to preload this segment.
+ */
+ if (!is_kernel_addr(exec)) {
+ if (preload_add(ti, exec))
+ slb_allocate_user(mm, exec);
+ }
+
+ /* Libraries and mmaps. */
+ if (!is_kernel_addr(mm->mmap_base)) {
+ if (preload_add(ti, mm->mmap_base))
+ slb_allocate_user(mm, mm->mmap_base);
+ }
+}
+
+void preload_new_slb_context(unsigned long start, unsigned long sp)
+{
+ struct thread_info *ti = current_thread_info();
+ struct mm_struct *mm = current->mm;
+ unsigned long heap = mm->start_brk;
+
+ /* Userspace entry address. */
+ if (!is_kernel_addr(start)) {
+ if (preload_add(ti, start))
+ slb_allocate_user(mm, start);
+ }
+
+ /* Top of stack, grows down. */
+ if (!is_kernel_addr(sp)) {
+ if (preload_add(ti, sp))
+ slb_allocate_user(mm, sp);
+ }
+
+ /* Bottom of heap, grows up. */
+ if (heap && !is_kernel_addr(heap)) {
+ if (preload_add(ti, heap))
+ slb_allocate_user(mm, heap);
+ }
+}
+
+
/* 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 pc = KSTK_EIP(tsk);
- unsigned long stack = KSTK_ESP(tsk);
- unsigned long exec_base;
+ struct thread_info *ti = task_thread_info(tsk);
+ u8 i;
/*
* We need interrupts hard-disabled here, not just soft-disabled,
@@ -314,7 +392,6 @@ void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
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++) {
@@ -354,24 +431,28 @@ void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
get_paca()->slb_used_bitmap = get_paca()->slb_kern_bitmap;
/*
- * preload some userspace segments into the SLB.
- * Almost all 32 and 64bit PowerPC executables are linked at
- * 0x10000000 so it makes sense to preload this segment.
+ * We gradually age out SLBs after a number of context switches to
+ * reduce reload overhead of unused entries (like we do with FP/VEC
+ * reload). Each time we wrap 256 switches, take an entry out of the
+ * SLB preload cache.
*/
- exec_base = 0x10000000;
+ tsk->thread.load_slb++;
+ if (!tsk->thread.load_slb) {
+ unsigned long pc = KSTK_EIP(tsk);
- if (is_kernel_addr(pc) || is_kernel_addr(stack) ||
- is_kernel_addr(exec_base))
- return;
+ preload_age(ti);
+ preload_add(ti, pc);
+ }
- slb_allocate_user(mm, pc);
+ for (i = 0; i < ti->slb_preload_nr; i++) {
+ unsigned long ea;
+ u8 idx;
- if (!esids_match(pc, stack))
- slb_allocate_user(mm, stack);
+ idx = (ti->slb_preload_tail + i) % SLB_PRELOAD_NR;
+ ea = (unsigned long)ti->slb_preload_esid[idx] << SID_SHIFT;
- if (!esids_match(pc, exec_base) &&
- !esids_match(stack, exec_base))
- slb_allocate_user(mm, exec_base);
+ slb_allocate_user(mm, ea);
+ }
}
void slb_set_size(u16 size)
@@ -644,11 +725,16 @@ long do_slb_fault(struct pt_regs *regs, unsigned long ea)
return slb_allocate_kernel(ea, id);
} else {
struct mm_struct *mm = current->mm;
+ long err;
if (unlikely(!mm))
return -EFAULT;
- return slb_allocate_user(mm, ea);
+ err = slb_allocate_user(mm, ea);
+ if (!err)
+ preload_add(current_thread_info(), ea);
+
+ return err;
}
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-23 02:22:57 +0000