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ANDROID: cfi: fix shadow rebasing

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If the module area base address changes when loading a new module, the
new CFI shadow will only cover the first allocated page for each existing
module. This will cause cross-DSO look-ups to functions elsewhere in the
module to fall back to a red-black tree, which may be slower.

Bug: 122963951
Change-Id: I9262034d39351afcd42590ead8d6384fc30a8ce8
Reported-by: Wu,Le <wule01@baidu.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
This commit is contained in:
Sami Tolvanen 2019-01-16 11:28:49 -08:00
parent f9b2849005
commit 046daa57dd
1 changed files with 9 additions and 1 deletions
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10
kernel/cfi.c
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@ -87,6 +87,14 @@ static inline unsigned long shadow_to_ptr(const struct cfi_shadow *s,
return (s->r.min_page + s->shadow[index]) << PAGE_SHIFT;
}
static inline unsigned long shadow_to_page(const struct cfi_shadow *s,
int index)
{
BUG_ON(index < 0 || index >= SHADOW_SIZE);
return (s->r.min_page + index) << PAGE_SHIFT;
}
static void prepare_next_shadow(const struct cfi_shadow __rcu *prev,
struct cfi_shadow *next)
{
@ -109,7 +117,7 @@ static void prepare_next_shadow(const struct cfi_shadow __rcu *prev,
if (prev->shadow[i] == SHADOW_INVALID)
continue;
index = ptr_to_shadow(next, shadow_to_ptr(prev, i));
index = ptr_to_shadow(next, shadow_to_page(prev, i));
if (index < 0)
continue;