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Improve error message for segv in read_barrier_handler

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If the page_body is a null pointer, then read_barrier_handler will
crash with an unrelated message. This commit improves the error message.

Before:

test.rb:1: [BUG] Couldn't unprotect page 0x0000000000000000, errno: Cannot allocate memory

After:

test.rb:1: [BUG] read_barrier_handler: segmentation fault at 0x14
This commit is contained in:
Peter Zhu 2022-07-06 17:30:36 -04:00
parent d6c98626da
commit f36859869f
Notes: git 2022-07-07 22:39:49 +09:00
1 changed files with 12 additions and 3 deletions
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15
gc.c
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@ -5210,18 +5210,27 @@ static void invalidate_moved_page(rb_objspace_t *objspace, struct heap_page *pag
#if GC_CAN_COMPILE_COMPACTION
static void
read_barrier_handler(uintptr_t address)
read_barrier_handler(uintptr_t original_address)
{
VALUE obj;
rb_objspace_t * objspace = &rb_objspace;
address -= address % BASE_SLOT_SIZE;
/* Calculate address aligned to slots. */
uintptr_t address = original_address - (original_address % BASE_SLOT_SIZE);
obj = (VALUE)address;
struct heap_page_body *page_body = GET_PAGE_BODY(obj);
/* If the page_body is NULL, then mprotect cannot handle it and will crash
* with "Cannot allocate memory". */
if (page_body == NULL) {
rb_bug("read_barrier_handler: segmentation fault at 0x%lx", original_address);
}
RB_VM_LOCK_ENTER();
{
unlock_page_body(objspace, GET_PAGE_BODY(obj));
unlock_page_body(objspace, page_body);
objspace->profile.read_barrier_faults++;