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authorMarc-André Lureau <marcandre.lureau@redhat.com>2018-01-16 16:11:52 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2018-02-07 14:09:24 +0100
commitd83414e1fd1941ca8228b5cf6a06697bd1ff7f83 (patch)
tree98c3ab60afc07fc2d5abed2ef243e774d0c1e2b1 /util/coroutine-ucontext.c
parent247724cb302af5d70c8853154b640dfabf2bbb56 (diff)
ucontext: annotate coroutine stack for ASAN
It helps ASAN to detect more leaks on coroutine stacks, and to get rid of some extra warnings. Before: tests/test-coroutine -p /basic/lifecycle /basic/lifecycle: ==20781==WARNING: ASan doesn't fully support makecontext/swapcontext functions and may produce false positives in some cases! ==20781==WARNING: ASan is ignoring requested __asan_handle_no_return: stack top: 0x7ffcb184d000; bottom 0x7ff6c4cfd000; size: 0x0005ecb50000 (25446121472) False positive error reports may follow For details see https://github.com/google/sanitizers/issues/189 OK After: tests/test-coroutine -p /basic/lifecycle /basic/lifecycle: ==21110==WARNING: ASan doesn't fully support makecontext/swapcontext functions and may produce false positives in some cases! OK A similar work would need to be done for sigaltstack & windows fibers to have similar coverage. Since ucontext is preferred, I didn't bother checking the other coroutine implementations for now. Update travis to fix the build with ASAN annotations. Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20180116151152.4040-4-marcandre.lureau@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'util/coroutine-ucontext.c')
-rw-r--r--util/coroutine-ucontext.c48
1 files changed, 48 insertions, 0 deletions
diff --git a/util/coroutine-ucontext.c b/util/coroutine-ucontext.c
index 6621f3f692..926d3402e3 100644
--- a/util/coroutine-ucontext.c
+++ b/util/coroutine-ucontext.c
@@ -31,6 +31,13 @@
#include <valgrind/valgrind.h>
#endif
+#if defined(__SANITIZE_ADDRESS__) || __has_feature(address_sanitizer)
+#ifdef CONFIG_ASAN_IFACE_FIBER
+#define CONFIG_ASAN 1
+#include <sanitizer/asan_interface.h>
+#endif
+#endif
+
typedef struct {
Coroutine base;
void *stack;
@@ -59,11 +66,37 @@ union cc_arg {
int i[2];
};
+static void finish_switch_fiber(void *fake_stack_save)
+{
+#ifdef CONFIG_ASAN
+ const void *bottom_old;
+ size_t size_old;
+
+ __sanitizer_finish_switch_fiber(fake_stack_save, &bottom_old, &size_old);
+
+ if (!leader.stack) {
+ leader.stack = (void *)bottom_old;
+ leader.stack_size = size_old;
+ }
+#endif
+}
+
+static void start_switch_fiber(void **fake_stack_save,
+ const void *bottom, size_t size)
+{
+#ifdef CONFIG_ASAN
+ __sanitizer_start_switch_fiber(fake_stack_save, bottom, size);
+#endif
+}
+
static void coroutine_trampoline(int i0, int i1)
{
union cc_arg arg;
CoroutineUContext *self;
Coroutine *co;
+ void *fake_stack_save = NULL;
+
+ finish_switch_fiber(NULL);
arg.i[0] = i0;
arg.i[1] = i1;
@@ -72,9 +105,13 @@ static void coroutine_trampoline(int i0, int i1)
/* Initialize longjmp environment and switch back the caller */
if (!sigsetjmp(self->env, 0)) {
+ start_switch_fiber(&fake_stack_save,
+ leader.stack, leader.stack_size);
siglongjmp(*(sigjmp_buf *)co->entry_arg, 1);
}
+ finish_switch_fiber(fake_stack_save);
+
while (true) {
co->entry(co->entry_arg);
qemu_coroutine_switch(co, co->caller, COROUTINE_TERMINATE);
@@ -87,6 +124,7 @@ Coroutine *qemu_coroutine_new(void)
ucontext_t old_uc, uc;
sigjmp_buf old_env;
union cc_arg arg = {0};
+ void *fake_stack_save = NULL;
/* The ucontext functions preserve signal masks which incurs a
* system call overhead. sigsetjmp(buf, 0)/siglongjmp() does not
@@ -122,8 +160,12 @@ Coroutine *qemu_coroutine_new(void)
/* swapcontext() in, siglongjmp() back out */
if (!sigsetjmp(old_env, 0)) {
+ start_switch_fiber(&fake_stack_save, co->stack, co->stack_size);
swapcontext(&old_uc, &uc);
}
+
+ finish_switch_fiber(fake_stack_save);
+
return &co->base;
}
@@ -169,13 +211,19 @@ qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
CoroutineUContext *from = DO_UPCAST(CoroutineUContext, base, from_);
CoroutineUContext *to = DO_UPCAST(CoroutineUContext, base, to_);
int ret;
+ void *fake_stack_save = NULL;
current = to_;
ret = sigsetjmp(from->env, 0);
if (ret == 0) {
+ start_switch_fiber(action == COROUTINE_TERMINATE ?
+ NULL : &fake_stack_save, to->stack, to->stack_size);
siglongjmp(to->env, action);
}
+
+ finish_switch_fiber(fake_stack_save);
+
return ret;
}