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Fix GC issues with ASAN fake stacks. #8903

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Merged
merged 5 commits into from
Jan 12, 2024
Merged

Fix GC issues with ASAN fake stacks. #8903

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dc83f2a
Pass down "stack start" variables from closer to the top of the stack
KJTsanaktsidis Nov 12, 2023
a52622e
Make stack bounds detection work with ASAN
KJTsanaktsidis Nov 12, 2023
386f180
Allow each_stack_location to accept context for the callback
KJTsanaktsidis Nov 12, 2023
45dd38e
Define special macros for asan/msan being enabled
KJTsanaktsidis Nov 12, 2023
75ebdbd
Mark asan fake stacks during machine stack marking
KJTsanaktsidis Nov 12, 2023
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Allow each_stack_location to accept context for the callback 
This is preparing for a more specialised, asan-aware version of
gc_mark_maybe which needs some additional context passed through.

[Bug #20001]
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@KJTsanaktsidis
KJTsanaktsidis committed Jan 10, 2024
commit 386f1805ba1692ad13eedb620678a8c70388706c
46 changes: 27 additions & 19 deletions gc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6547,32 +6547,38 @@ ruby_stack_check(void)
return stack_check(GET_EC(), STACKFRAME_FOR_CALL_CFUNC);
}

ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS(static void each_location(rb_objspace_t *objspace, register const VALUE *x, register long n, void (*cb)(rb_objspace_t *, VALUE)));
ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS(static void each_location(rb_objspace_t *objspace, register const VALUE *x, register long n, void *ctx, void (*cb)(rb_objspace_t *, void *, VALUE)));
static void
each_location(rb_objspace_t *objspace, register const VALUE *x, register long n, void (*cb)(rb_objspace_t *, VALUE))
each_location(rb_objspace_t *objspace, register const VALUE *x, register long n, void *ctx, void (*cb)(rb_objspace_t *, void *, VALUE))
{
VALUE v;
while (n--) {
v = *x;
cb(objspace, v);
cb(objspace, ctx, v);
x++;
}
}

static void
gc_mark_locations(rb_objspace_t *objspace, const VALUE *start, const VALUE *end, void (*cb)(rb_objspace_t *, VALUE))
gc_mark_locations(rb_objspace_t *objspace, const VALUE *start, const VALUE *end, void *ctx, void (*cb)(rb_objspace_t *, void *, VALUE))
{
long n;

if (end <= start) return;
n = end - start;
each_location(objspace, start, n, cb);
each_location(objspace, start, n, ctx, cb);
}

static void
gc_mark_maybe_cb(rb_objspace_t *objspace, void *ctx, VALUE obj)
{
gc_mark_maybe(objspace, obj);
}

void
rb_gc_mark_locations(const VALUE *start, const VALUE *end)
{
gc_mark_locations(&rb_objspace, start, end, gc_mark_maybe);
gc_mark_locations(&rb_objspace, start, end, NULL, gc_mark_maybe_cb);
}

void
Expand Down Expand Up @@ -6818,7 +6824,8 @@ mark_const_tbl(rb_objspace_t *objspace, struct rb_id_table *tbl)
#endif

static void each_stack_location(rb_objspace_t *objspace, const rb_execution_context_t *ec,
const VALUE *stack_start, const VALUE *stack_end, void (*cb)(rb_objspace_t *, VALUE));
const VALUE *stack_start, const VALUE *stack_end, void *ctx,
void (*cb)(rb_objspace_t *, void *, VALUE));

#if defined(__wasm__)

Expand All @@ -6838,10 +6845,10 @@ static void
mark_current_machine_context(rb_objspace_t *objspace, rb_execution_context_t *ec)
{
emscripten_scan_stack(rb_mark_locations);
each_stack_location(objspace, ec, rb_stack_range_tmp[0], rb_stack_range_tmp[1], gc_mark_maybe);
each_stack_location(objspace, ec, rb_stack_range_tmp[0], rb_stack_range_tmp[1], gc_mark_maybe_cb);

emscripten_scan_registers(rb_mark_locations);
each_stack_location(objspace, ec, rb_stack_range_tmp[0], rb_stack_range_tmp[1], gc_mark_maybe);
each_stack_location(objspace, ec, rb_stack_range_tmp[0], rb_stack_range_tmp[1], gc_mark_maybe_cb);
}
# else // use Asyncify version

Expand All @@ -6851,10 +6858,10 @@ mark_current_machine_context(rb_objspace_t *objspace, rb_execution_context_t *ec
VALUE *stack_start, *stack_end;
SET_STACK_END;
GET_STACK_BOUNDS(stack_start, stack_end, 1);
each_stack_location(objspace, ec, stack_start, stack_end, gc_mark_maybe);
each_stack_location(objspace, ec, stack_start, stack_end, gc_mark_maybe_cb);

rb_wasm_scan_locals(rb_mark_locations);
each_stack_location(objspace, ec, rb_stack_range_tmp[0], rb_stack_range_tmp[1], gc_mark_maybe);
each_stack_location(objspace, ec, rb_stack_range_tmp[0], rb_stack_range_tmp[1], gc_mark_maybe_cb);
}

# endif
Expand All @@ -6881,40 +6888,41 @@ mark_current_machine_context(rb_objspace_t *objspace, rb_execution_context_t *ec
SET_STACK_END;
GET_STACK_BOUNDS(stack_start, stack_end, 1);

each_location(objspace, save_regs_gc_mark.v, numberof(save_regs_gc_mark.v), gc_mark_maybe);
each_location(objspace, save_regs_gc_mark.v, numberof(save_regs_gc_mark.v), NULL, gc_mark_maybe_cb);

each_stack_location(objspace, ec, stack_start, stack_end, gc_mark_maybe);
each_stack_location(objspace, ec, stack_start, stack_end, NULL, gc_mark_maybe_cb);
}
#endif

static void
each_machine_stack_value(const rb_execution_context_t *ec, void (*cb)(rb_objspace_t *, VALUE))
each_machine_stack_value(const rb_execution_context_t *ec, void *ctx, void (*cb)(rb_objspace_t *, void *, VALUE))
{
rb_objspace_t *objspace = &rb_objspace;
VALUE *stack_start, *stack_end;

GET_STACK_BOUNDS(stack_start, stack_end, 0);
RUBY_DEBUG_LOG("ec->th:%u stack_start:%p stack_end:%p", rb_ec_thread_ptr(ec)->serial, stack_start, stack_end);
each_stack_location(objspace, ec, stack_start, stack_end, cb);
each_stack_location(objspace, ec, stack_start, stack_end, ctx, cb);
}

void
rb_gc_mark_machine_stack(const rb_execution_context_t *ec)
{
each_machine_stack_value(ec, gc_mark_maybe);
each_machine_stack_value(ec, NULL, gc_mark_maybe_cb);
}

static void
each_stack_location(rb_objspace_t *objspace, const rb_execution_context_t *ec,
const VALUE *stack_start, const VALUE *stack_end, void (*cb)(rb_objspace_t *, VALUE))
const VALUE *stack_start, const VALUE *stack_end, void *ctx,
void (*cb)(rb_objspace_t *, void *, VALUE))
{

gc_mark_locations(objspace, stack_start, stack_end, cb);
gc_mark_locations(objspace, stack_start, stack_end, ctx, cb);

#if defined(__mc68000__)
gc_mark_locations(objspace,
(VALUE*)((char*)stack_start + 2),
(VALUE*)((char*)stack_end - 2), cb);
(VALUE*)((char*)stack_end - 2), ctx, cb);
#endif
}

Expand Down