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[Qemu-devel] [PATCH 1/5] translate-all.c: Don't pass puc, locked to tb_i
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH 1/5] translate-all.c: Don't pass puc, locked to tb_invalidate_phys_page() |
Date: |
Mon, 16 May 2016 17:09:48 +0100 |
The user-mode-only function tb_invalidate_phys_page() is only
called from two places:
* page_unprotect(), which passes in a non-zero pc, a puc pointer
and the value 'true' for the locked argument
* page_set_flags(), which passes in a zero pc, a NULL puc pointer
and a 'false' locked argument
If the pc is non-zero then we may call cpu_resume_from_signal(),
which does a longjmp out of the calling code (and out of the
signal handler); this is to cover the case of a target CPU with
"precise self-modifying code" (currently only x86) executing
a store instruction which modifies code in the same TB as the
store itself. Rather than doing the longjump directly here,
return a flag to the caller which indicates whether the current
TB was modified, and move the longjump to page_unprotect.
Signed-off-by: Peter Maydell <address@hidden>
---
translate-all.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)
diff --git a/translate-all.c b/translate-all.c
index b54f472..4820d2e 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -1438,10 +1438,13 @@ void tb_invalidate_phys_page_fast(tb_page_addr_t start,
int len)
}
}
#else
-/* Called with mmap_lock held. */
-static void tb_invalidate_phys_page(tb_page_addr_t addr,
- uintptr_t pc, void *puc,
- bool locked)
+/* Called with mmap_lock held. If pc is not 0 then it indicates the
+ * host PC of the faulting store instruction that caused this invalidate.
+ * Returns true if the caller needs to abort execution of the current
+ * TB (because it was modified by this store and the guest CPU has
+ * precise-SMC semantics).
+ */
+static bool tb_invalidate_phys_page(tb_page_addr_t addr, uintptr_t pc)
{
TranslationBlock *tb;
PageDesc *p;
@@ -1459,7 +1462,7 @@ static void tb_invalidate_phys_page(tb_page_addr_t addr,
addr &= TARGET_PAGE_MASK;
p = page_find(addr >> TARGET_PAGE_BITS);
if (!p) {
- return;
+ return false;
}
tb = p->first_tb;
#ifdef TARGET_HAS_PRECISE_SMC
@@ -1498,12 +1501,10 @@ static void tb_invalidate_phys_page(tb_page_addr_t addr,
modifying the memory. It will ensure that it cannot modify
itself */
tb_gen_code(cpu, current_pc, current_cs_base, current_flags, 1);
- if (locked) {
- mmap_unlock();
- }
- cpu_resume_from_signal(cpu, puc);
+ return true;
}
#endif
+ return false;
}
#endif
@@ -1902,7 +1903,7 @@ void page_set_flags(target_ulong start, target_ulong end,
int flags)
if (!(p->flags & PAGE_WRITE) &&
(flags & PAGE_WRITE) &&
p->first_tb) {
- tb_invalidate_phys_page(addr, 0, NULL, false);
+ tb_invalidate_phys_page(addr, 0);
}
p->flags = flags;
}
@@ -1996,7 +1997,10 @@ int page_unprotect(target_ulong address, uintptr_t pc,
void *puc)
/* and since the content will be modified, we must invalidate
the corresponding translated code. */
- tb_invalidate_phys_page(addr, pc, puc, true);
+ if (tb_invalidate_phys_page(addr, pc)) {
+ mmap_unlock();
+ cpu_resume_from_signal(current_cpu, puc);
+ }
#ifdef DEBUG_TB_CHECK
tb_invalidate_check(addr);
#endif
--
1.9.1