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[Qemu-devel] [PATCH v3 05/17] translate-all: iterate over TBs in a page
From: |
Emilio G. Cota |
Subject: |
[Qemu-devel] [PATCH v3 05/17] translate-all: iterate over TBs in a page with PAGE_FOR_EACH_TB |
Date: |
Mon, 21 May 2018 19:39:15 -0400 |
This commit does several things, but to avoid churn I merged them all
into the same commit. To wit:
- Use uintptr_t instead of TranslationBlock * for the list of TBs in a page.
Just like we did in (c37e6d7e "tcg: Use uintptr_t type for
jmp_list_{next|first} fields of TB"), the rationale is the same: these
are tagged pointers, not pointers. So use a more appropriate type.
- Only check the least significant bit of the tagged pointers. Masking
with 3/~3 is unnecessary and confusing.
- Introduce the TB_FOR_EACH_TAGGED macro, and use it to define
PAGE_FOR_EACH_TB, which improves readability. Note that
TB_FOR_EACH_TAGGED will gain another user in a subsequent patch.
- Update tb_page_remove to use PAGE_FOR_EACH_TB. In case there
is a bug and we attempt to remove a TB that is not in the list, instead
of segfaulting (since the list is NULL-terminated) we will reach
g_assert_not_reached().
Reviewed-by: Richard Henderson <address@hidden>
Signed-off-by: Emilio G. Cota <address@hidden>
---
include/exec/exec-all.h | 2 +-
accel/tcg/translate-all.c | 62 ++++++++++++++++++++++-------------------------
2 files changed, 30 insertions(+), 34 deletions(-)
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 6207b4d..b2d8c8e 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -359,7 +359,7 @@ struct TranslationBlock {
struct TranslationBlock *orig_tb;
/* first and second physical page containing code. The lower bit
of the pointer tells the index in page_next[] */
- struct TranslationBlock *page_next[2];
+ uintptr_t page_next[2];
tb_page_addr_t page_addr[2];
/* The following data are used to directly call another TB from
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 8caf28d..7302d05 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -103,7 +103,7 @@
typedef struct PageDesc {
/* list of TBs intersecting this ram page */
- TranslationBlock *first_tb;
+ uintptr_t first_tb;
#ifdef CONFIG_SOFTMMU
/* in order to optimize self modifying code, we count the number
of lookups we do to a given page to use a bitmap */
@@ -114,6 +114,15 @@ typedef struct PageDesc {
#endif
} PageDesc;
+/* list iterators for lists of tagged pointers in TranslationBlock */
+#define TB_FOR_EACH_TAGGED(head, tb, n, field) \
+ for (n = (head) & 1, tb = (TranslationBlock *)((head) & ~1); \
+ tb; tb = (TranslationBlock *)tb->field[n], n = (uintptr_t)tb & 1, \
+ tb = (TranslationBlock *)((uintptr_t)tb & ~1))
+
+#define PAGE_FOR_EACH_TB(pagedesc, tb, n) \
+ TB_FOR_EACH_TAGGED((pagedesc)->first_tb, tb, n, page_next)
+
/* In system mode we want L1_MAP to be based on ram offsets,
while in user mode we want it to be based on virtual addresses. */
#if !defined(CONFIG_USER_ONLY)
@@ -815,7 +824,7 @@ static void page_flush_tb_1(int level, void **lp)
PageDesc *pd = *lp;
for (i = 0; i < V_L2_SIZE; ++i) {
- pd[i].first_tb = NULL;
+ pd[i].first_tb = (uintptr_t)NULL;
invalidate_page_bitmap(pd + i);
}
} else {
@@ -943,21 +952,21 @@ static void tb_page_check(void)
#endif /* CONFIG_USER_ONLY */
-static inline void tb_page_remove(TranslationBlock **ptb, TranslationBlock *tb)
+static inline void tb_page_remove(PageDesc *pd, TranslationBlock *tb)
{
TranslationBlock *tb1;
+ uintptr_t *pprev;
unsigned int n1;
- for (;;) {
- tb1 = *ptb;
- n1 = (uintptr_t)tb1 & 3;
- tb1 = (TranslationBlock *)((uintptr_t)tb1 & ~3);
+ pprev = &pd->first_tb;
+ PAGE_FOR_EACH_TB(pd, tb1, n1) {
if (tb1 == tb) {
- *ptb = tb1->page_next[n1];
- break;
+ *pprev = tb1->page_next[n1];
+ return;
}
- ptb = &tb1->page_next[n1];
+ pprev = &tb1->page_next[n1];
}
+ g_assert_not_reached();
}
/* remove the TB from a list of TBs jumping to the n-th jump target of the TB
*/
@@ -1045,12 +1054,12 @@ void tb_phys_invalidate(TranslationBlock *tb,
tb_page_addr_t page_addr)
/* remove the TB from the page list */
if (tb->page_addr[0] != page_addr) {
p = page_find(tb->page_addr[0] >> TARGET_PAGE_BITS);
- tb_page_remove(&p->first_tb, tb);
+ tb_page_remove(p, tb);
invalidate_page_bitmap(p);
}
if (tb->page_addr[1] != -1 && tb->page_addr[1] != page_addr) {
p = page_find(tb->page_addr[1] >> TARGET_PAGE_BITS);
- tb_page_remove(&p->first_tb, tb);
+ tb_page_remove(p, tb);
invalidate_page_bitmap(p);
}
@@ -1081,10 +1090,7 @@ static void build_page_bitmap(PageDesc *p)
p->code_bitmap = bitmap_new(TARGET_PAGE_SIZE);
- tb = p->first_tb;
- while (tb != NULL) {
- n = (uintptr_t)tb & 3;
- tb = (TranslationBlock *)((uintptr_t)tb & ~3);
+ PAGE_FOR_EACH_TB(p, tb, n) {
/* NOTE: this is subtle as a TB may span two physical pages */
if (n == 0) {
/* NOTE: tb_end may be after the end of the page, but
@@ -1099,7 +1105,6 @@ static void build_page_bitmap(PageDesc *p)
tb_end = ((tb->pc + tb->size) & ~TARGET_PAGE_MASK);
}
bitmap_set(p->code_bitmap, tb_start, tb_end - tb_start);
- tb = tb->page_next[n];
}
}
#endif
@@ -1122,9 +1127,9 @@ static inline void tb_alloc_page(TranslationBlock *tb,
p = page_find_alloc(page_addr >> TARGET_PAGE_BITS, 1);
tb->page_next[n] = p->first_tb;
#ifndef CONFIG_USER_ONLY
- page_already_protected = p->first_tb != NULL;
+ page_already_protected = p->first_tb != (uintptr_t)NULL;
#endif
- p->first_tb = (TranslationBlock *)((uintptr_t)tb | n);
+ p->first_tb = (uintptr_t)tb | n;
invalidate_page_bitmap(p);
#if defined(CONFIG_USER_ONLY)
@@ -1401,7 +1406,7 @@ void tb_invalidate_phys_range(tb_page_addr_t start,
tb_page_addr_t end)
void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end,
int is_cpu_write_access)
{
- TranslationBlock *tb, *tb_next;
+ TranslationBlock *tb;
tb_page_addr_t tb_start, tb_end;
PageDesc *p;
int n;
@@ -1432,11 +1437,7 @@ void tb_invalidate_phys_page_range(tb_page_addr_t start,
tb_page_addr_t end,
/* we remove all the TBs in the range [start, end[ */
/* XXX: see if in some cases it could be faster to invalidate all
the code */
- tb = p->first_tb;
- while (tb != NULL) {
- n = (uintptr_t)tb & 3;
- tb = (TranslationBlock *)((uintptr_t)tb & ~3);
- tb_next = tb->page_next[n];
+ PAGE_FOR_EACH_TB(p, tb, n) {
/* NOTE: this is subtle as a TB may span two physical pages */
if (n == 0) {
/* NOTE: tb_end may be after the end of the page, but
@@ -1474,7 +1475,6 @@ void tb_invalidate_phys_page_range(tb_page_addr_t start,
tb_page_addr_t end,
#endif /* TARGET_HAS_PRECISE_SMC */
tb_phys_invalidate(tb, -1);
}
- tb = tb_next;
}
#if !defined(CONFIG_USER_ONLY)
/* if no code remaining, no need to continue to use slow writes */
@@ -1568,18 +1568,15 @@ static bool tb_invalidate_phys_page(tb_page_addr_t
addr, uintptr_t pc)
}
tb_lock();
- tb = p->first_tb;
#ifdef TARGET_HAS_PRECISE_SMC
- if (tb && pc != 0) {
+ if (p->first_tb && pc != 0) {
current_tb = tcg_tb_lookup(pc);
}
if (cpu != NULL) {
env = cpu->env_ptr;
}
#endif
- while (tb != NULL) {
- n = (uintptr_t)tb & 3;
- tb = (TranslationBlock *)((uintptr_t)tb & ~3);
+ PAGE_FOR_EACH_TB(p, tb, n) {
#ifdef TARGET_HAS_PRECISE_SMC
if (current_tb == tb &&
(current_tb->cflags & CF_COUNT_MASK) != 1) {
@@ -1596,9 +1593,8 @@ static bool tb_invalidate_phys_page(tb_page_addr_t addr,
uintptr_t pc)
}
#endif /* TARGET_HAS_PRECISE_SMC */
tb_phys_invalidate(tb, addr);
- tb = tb->page_next[n];
}
- p->first_tb = NULL;
+ p->first_tb = (uintptr_t)NULL;
#ifdef TARGET_HAS_PRECISE_SMC
if (current_tb_modified) {
/* Force execution of one insn next time. */
--
2.7.4
- [Qemu-devel] [PATCH v3 00/17] tcg: tb_lock removal redux v3, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 04/17] tcg: move tb_ctx.tb_phys_invalidate_count to tcg_ctx, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 07/17] translate-all: remove hole in PageDesc, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 12/17] translate-all: introduce assert_no_pages_locked, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 06/17] translate-all: make l1_map lockless, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 08/17] translate-all: work page-by-page in tb_invalidate_phys_range_1, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 15/17] cputlb: remove tb_lock from tlb_flush functions, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 05/17] translate-all: iterate over TBs in a page with PAGE_FOR_EACH_TB,
Emilio G. Cota <=
- [Qemu-devel] [PATCH v3 16/17] translate-all: remove tb_lock mention from cpu_restore_state_from_tb, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 13/17] translate-all: discard TB when tb_link_page returns an existing matching TB, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 03/17] tcg: track TBs with per-region BST's, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 10/17] translate-all: use per-page locking in !user-mode, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 01/17] qht: require a default comparison function, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 09/17] translate-all: move tb_invalidate_phys_page_range up in the file, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 02/17] qht: return existing entry when qht_insert fails, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 17/17] tcg: remove tb_lock, Emilio G. Cota, 2018/05/21
- [Qemu-devel] [PATCH v3 11/17] translate-all: add page_locked assertions, Emilio G. Cota, 2018/05/21