[PATCH v1 2/2] arm64: tlb: Use the TLBI RANGE feature in arm64
From: Zhenyu Ye
Date: Thu Jul 09 2020 - 05:11:27 EST
Add __TLBI_VADDR_RANGE macro and rewrite __flush_tlb_range().
Signed-off-by: Zhenyu Ye <yezhenyu2@xxxxxxxxxx>
---
arch/arm64/include/asm/tlbflush.h | 156 ++++++++++++++++++++++++------
1 file changed, 126 insertions(+), 30 deletions(-)
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index 39aed2efd21b..30e52eae973b 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -60,6 +60,31 @@
__ta; \
})
+/*
+ * Get translation granule of the system, which is decided by
+ * PAGE_SIZE. Used by TTL.
+ * - 4KB : 1
+ * - 16KB : 2
+ * - 64KB : 3
+ */
+#define TLBI_TTL_TG_4K 1
+#define TLBI_TTL_TG_16K 2
+#define TLBI_TTL_TG_64K 3
+
+static inline unsigned long get_trans_granule(void)
+{
+ switch (PAGE_SIZE) {
+ case SZ_4K:
+ return TLBI_TTL_TG_4K;
+ case SZ_16K:
+ return TLBI_TTL_TG_16K;
+ case SZ_64K:
+ return TLBI_TTL_TG_64K;
+ default:
+ return 0;
+ }
+}
+
/*
* Level-based TLBI operations.
*
@@ -73,29 +98,15 @@
* in asm/stage2_pgtable.h.
*/
#define TLBI_TTL_MASK GENMASK_ULL(47, 44)
-#define TLBI_TTL_TG_4K 1
-#define TLBI_TTL_TG_16K 2
-#define TLBI_TTL_TG_64K 3
#define __tlbi_level(op, addr, level) do { \
u64 arg = addr; \
\
if (cpus_have_const_cap(ARM64_HAS_ARMv8_4_TTL) && \
+ !cpus_have_const_cap(ARM64_HAS_TLBI_RANGE) && \
level) { \
u64 ttl = level & 3; \
- \
- switch (PAGE_SIZE) { \
- case SZ_4K: \
- ttl |= TLBI_TTL_TG_4K << 2; \
- break; \
- case SZ_16K: \
- ttl |= TLBI_TTL_TG_16K << 2; \
- break; \
- case SZ_64K: \
- ttl |= TLBI_TTL_TG_64K << 2; \
- break; \
- } \
- \
+ ttl |= get_trans_granule() << 2; \
arg &= ~TLBI_TTL_MASK; \
arg |= FIELD_PREP(TLBI_TTL_MASK, ttl); \
} \
@@ -108,6 +119,49 @@
__tlbi_level(op, (arg | USER_ASID_FLAG), level); \
} while (0)
+#define __tlbi_last_level(op1, op2, arg, last_level, tlb_level) do { \
+ if (last_level) { \
+ __tlbi_level(op1, arg, tlb_level); \
+ __tlbi_user_level(op1, arg, tlb_level); \
+ } else { \
+ __tlbi_level(op2, arg, tlb_level); \
+ __tlbi_user_level(op2, arg, tlb_level); \
+ } \
+} while (0)
+
+/*
+ * This macro creates a properly formatted VA operand for the TLBI RANGE.
+ * The value bit assignments are:
+ *
+ * +----------+------+-------+-------+-------+----------------------+
+ * | ASID | TG | SCALE | NUM | TTL | BADDR |
+ * +-----------------+-------+-------+-------+----------------------+
+ * |63 48|47 46|45 44|43 39|38 37|36 0|
+ *
+ * The address range is determined by below formula:
+ * [BADDR, BADDR + (NUM + 1) * 2^(5*SCALE + 1) * PAGESIZE)
+ *
+ */
+#define __TLBI_VADDR_RANGE(addr, asid, scale, num, ttl) \
+ ({ \
+ unsigned long __ta = (addr) >> PAGE_SHIFT; \
+ __ta &= GENMASK_ULL(36, 0); \
+ __ta |= (unsigned long)(ttl) << 37; \
+ __ta |= (unsigned long)(num) << 39; \
+ __ta |= (unsigned long)(scale) << 44; \
+ __ta |= get_trans_granule() << 46; \
+ __ta |= (unsigned long)(asid) << 48; \
+ __ta; \
+ })
+
+/* These macros are used by the TLBI RANGE feature. */
+#define __TLBI_RANGE_PAGES(num, scale) (((num) + 1) << (5 * (scale) + 1))
+#define MAX_TLBI_RANGE_PAGES __TLBI_RANGE_PAGES(31, 3)
+
+#define TLBI_RANGE_MASK GENMASK_ULL(4, 0)
+#define __TLBI_RANGE_NUM(range, scale) \
+ (((range) >> (5 * (scale) + 1)) & TLBI_RANGE_MASK)
+
/*
* TLB Invalidation
* ================
@@ -232,32 +286,74 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
unsigned long stride, bool last_level,
int tlb_level)
{
+ int num = 0;
+ int scale = 0;
unsigned long asid = ASID(vma->vm_mm);
unsigned long addr;
+ unsigned long pages;
start = round_down(start, stride);
end = round_up(end, stride);
+ pages = (end - start) >> PAGE_SHIFT;
- if ((end - start) >= (MAX_TLBI_OPS * stride)) {
+ if ((!cpus_have_const_cap(ARM64_HAS_TLBI_RANGE) &&
+ (end - start) >= (MAX_TLBI_OPS * stride)) ||
+ pages >= MAX_TLBI_RANGE_PAGES) {
flush_tlb_mm(vma->vm_mm);
return;
}
- /* Convert the stride into units of 4k */
- stride >>= 12;
-
- start = __TLBI_VADDR(start, asid);
- end = __TLBI_VADDR(end, asid);
-
dsb(ishst);
- for (addr = start; addr < end; addr += stride) {
- if (last_level) {
- __tlbi_level(vale1is, addr, tlb_level);
- __tlbi_user_level(vale1is, addr, tlb_level);
- } else {
- __tlbi_level(vae1is, addr, tlb_level);
- __tlbi_user_level(vae1is, addr, tlb_level);
+
+ /*
+ * When cpu does not support TLBI RANGE feature, we flush the tlb
+ * entries one by one at the granularity of 'stride'.
+ * When cpu supports the TLBI RANGE feature, then:
+ * 1. If pages is odd, flush the first page through non-RANGE
+ * instruction;
+ * 2. For remaining pages: The minimum range granularity is decided
+ * by 'scale', so we can not flush all pages by one instruction
+ * in some cases.
+ *
+ * For example, when the pages = 0xe81a, let's start 'scale' from
+ * maximum, and find right 'num' for each 'scale':
+ *
+ * When scale = 3, we can flush no pages because the minumum
+ * range is 2^(5*3 + 1) = 0x10000.
+ * When scale = 2, the minimum range is 2^(5*2 + 1) = 0x800, we can
+ * flush 0xe800 pages this time, the num = 0xe800/0x800 - 1 = 0x1c.
+ * Remain pages is 0x1a;
+ * When scale = 1, the minimum range is 2^(5*1 + 1) = 0x40, no page
+ * can be flushed.
+ * When scale = 0, we flush the remaining 0x1a pages, the num =
+ * 0x1a/0x2 - 1 = 0xd.
+ *
+ * However, in most scenarios, the pages = 1 when flush_tlb_range() is
+ * called. Start from scale = 3 or other proper value (such as scale =
+ * ilog2(pages)), will incur extra overhead.
+ * So increase 'scale' from 0 to maximum, the flush order is exactly
+ * opposite to the example.
+ */
+ while (pages > 0) {
+ if (cpus_have_const_cap(ARM64_HAS_TLBI_RANGE) &&
+ pages % 2 == 0) {
+ num = __TLBI_RANGE_NUM(pages, scale) - 1;
+ if (num >= 0) {
+ addr = __TLBI_VADDR_RANGE(start, asid, scale,
+ num, tlb_level);
+ __tlbi_last_level(rvale1is, rvae1is, addr,
+ last_level, tlb_level);
+ start += __TLBI_RANGE_PAGES(num, scale) << PAGE_SHIFT;
+ pages -= __TLBI_RANGE_PAGES(num, scale);
+ }
+ scale++;
+ continue;
}
+
+ addr = __TLBI_VADDR(start, asid);
+ __tlbi_last_level(vale1is, vae1is, addr, last_level, tlb_level);
+ start += stride;
+ pages -= stride >> PAGE_SHIFT;
}
dsb(ish);
}
--
2.19.1