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[Qemu-devel] [PATCH v3 15/15] translate-all: mark updates to PageDesc as
From: |
Alex Bennée |
Subject: |
[Qemu-devel] [PATCH v3 15/15] translate-all: mark updates to PageDesc as atomic |
Date: |
Fri, 30 Sep 2016 22:31:06 +0100 |
Updates to the internal page table are protected by the mmap_lock.
However for defined C11 semantics things that are access across threads
need to accessed using at least relaxed atomics.
Signed-off-by: Alex Bennée <address@hidden>
---
translate-all.c | 67 +++++++++++++++++++++++++++++----------------------------
1 file changed, 34 insertions(+), 33 deletions(-)
diff --git a/translate-all.c b/translate-all.c
index a6262ae..2d6c0e8 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -805,22 +805,21 @@ static inline void invalidate_page_bitmap(PageDesc *p)
static void page_flush_tb_1(int level, void **lp)
{
int i;
+ PageDesc *pd = atomic_rcu_read(lp);
- if (*lp == NULL) {
- return;
- }
- if (level == 0) {
- PageDesc *pd = *lp;
+ if (pd) {
+ if (level == 0) {
- for (i = 0; i < V_L2_SIZE; ++i) {
- pd[i].first_tb = NULL;
- invalidate_page_bitmap(pd + i);
- }
- } else {
- void **pp = *lp;
+ for (i = 0; i < V_L2_SIZE; ++i) {
+ atomic_set(&pd[i].first_tb, NULL);
+ invalidate_page_bitmap(pd + i);
+ }
+ } else {
+ void **pp = (void **) pd;
- for (i = 0; i < V_L2_SIZE; ++i) {
- page_flush_tb_1(level - 1, pp + i);
+ for (i = 0; i < V_L2_SIZE; ++i) {
+ page_flush_tb_1(level - 1, pp + i);
+ }
}
}
}
@@ -1360,7 +1359,7 @@ 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;
+ tb = atomic_read(&p->first_tb);
while (tb != NULL) {
n = (uintptr_t)tb & 3;
tb = (TranslationBlock *)((uintptr_t)tb & ~3);
@@ -1968,16 +1967,15 @@ void page_set_flags(target_ulong start, target_ulong
end, int flags)
the code inside. */
if (!(p->flags & PAGE_WRITE) &&
(flags & PAGE_WRITE) &&
- p->first_tb) {
+ atomic_read(&p->first_tb)) {
tb_invalidate_phys_page(addr, 0);
}
- p->flags = flags;
+ atomic_set(&p->flags, flags);
}
}
int page_check_range(target_ulong start, target_ulong len, int flags)
{
- PageDesc *p;
target_ulong end;
target_ulong addr;
@@ -2003,28 +2001,31 @@ int page_check_range(target_ulong start, target_ulong
len, int flags)
for (addr = start, len = end - start;
len != 0;
len -= TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) {
- p = page_find(addr >> TARGET_PAGE_BITS);
- if (!p) {
- return -1;
- }
- if (!(p->flags & PAGE_VALID)) {
- return -1;
- }
+ PageDesc *p = page_find(addr >> TARGET_PAGE_BITS);
+ if (p) {
+ int cur_flags = atomic_read(&p->flags);
- if ((flags & PAGE_READ) && !(p->flags & PAGE_READ)) {
- return -1;
- }
- if (flags & PAGE_WRITE) {
- if (!(p->flags & PAGE_WRITE_ORG)) {
+ if (!(cur_flags & PAGE_VALID)) {
return -1;
}
- /* unprotect the page if it was put read-only because it
- contains translated code */
- if (!(p->flags & PAGE_WRITE)) {
- if (!page_unprotect(addr, 0)) {
+
+ if ((flags & PAGE_READ) && !(cur_flags & PAGE_READ)) {
+ return -1;
+ }
+ if (flags & PAGE_WRITE) {
+ if (!(cur_flags & PAGE_WRITE_ORG)) {
return -1;
}
+ /* unprotect the page if it was put read-only because it
+ contains translated code */
+ if (!(cur_flags & PAGE_WRITE)) {
+ if (!page_unprotect(addr, 0)) {
+ return -1;
+ }
+ }
}
+ } else {
+ return -1;
}
}
return 0;
--
2.9.3
- [Qemu-devel] [PATCH v3 04/15] tcg/optimize: move default return out of if statement, (continued)
- [Qemu-devel] [PATCH v3 04/15] tcg/optimize: move default return out of if statement, Alex Bennée, 2016/09/30
- [Qemu-devel] [PATCH v3 10/15] linux-user/syscall: extend lock around cpu-list, Alex Bennée, 2016/09/30
- [Qemu-devel] [PATCH v3 05/15] seqlock: use atomic writes for the sequence, Alex Bennée, 2016/09/30
- [Qemu-devel] [PATCH v3 08/15] cpu: atomically modify cpu->exit_request, Alex Bennée, 2016/09/30
- [Qemu-devel] [PATCH v3 07/15] qom/cpu: atomically clear the tb_jmp_cache, Alex Bennée, 2016/09/30
- [Qemu-devel] [PATCH v3 11/15] qga/command: use QEMU atomic primitives, Alex Bennée, 2016/09/30
- [Qemu-devel] [PATCH v3 12/15] .travis.yml: add gcc sanitizer build, Alex Bennée, 2016/09/30
- [Qemu-devel] [PATCH v3 13/15] tcg: ensure cpu_tb_exec/tb_gen_code use atomic_read/write, Alex Bennée, 2016/09/30
- [Qemu-devel] [PATCH v3 15/15] translate-all: mark updates to PageDesc as atomic,
Alex Bennée <=
- [Qemu-devel] [PATCH v3 09/15] util/qht: atomically set b->hashes, Alex Bennée, 2016/09/30
- [Qemu-devel] [PATCH v3 14/15] tcg: update remaining TranslationBuffer fields atomically, Alex Bennée, 2016/09/30
- Re: [Qemu-devel] [PATCH v3 00/15] A number of fixes for ThreadSanitizer, no-reply, 2016/09/30
- Re: [Qemu-devel] [PATCH v3 00/15] A number of fixes for ThreadSanitizer, no-reply, 2016/09/30