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Fix GC scanning of registers on x86_64 architectures.

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It is possible for jmp_buf to not be word-aligned or addresses
in the register dump to not be word-aligned. This can result in
either addresses in registers being missed or even addresses on
the stack past the register area not being scanned properly.
This commit is contained in:
Reimer Behrends
2015-05-07 14:35:39 +02:00
parent b9e02b1efc
commit 2a08bbdf31
2 changed files with 18 additions and 0 deletions
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9
lib/system/gc.nim
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@@ -922,6 +922,15 @@ else:
if c_setjmp(registers) == 0'i32: # To fill the C stack with registers.
var max = cast[ByteAddress](gch.stackBottom)
var sp = cast[ByteAddress](addr(registers))
when defined(amd64):
# words within the jmp_buf structure may not be properly aligned.
let regEnd = sp +% sizeof(registers)
while sp <% regEnd:
gcMark(gch, cast[PPointer](sp)[])
gcMark(gch, cast[PPointer](sp +% sizeof(pointer) div 2)[])
sp = sp +% sizeof(pointer)
# Make sure sp is word-aligned
sp = sp and not (sizeof(pointer) - 1)
# loop unrolled:
while sp <% max - 8*sizeof(pointer):
gcMark(gch, cast[PStackSlice](sp)[0])

9
lib/system/gc_ms.nim
View File

@@ -514,6 +514,15 @@ else:
if c_setjmp(registers) == 0'i32: # To fill the C stack with registers.
var max = cast[ByteAddress](gch.stackBottom)
var sp = cast[ByteAddress](addr(registers))
when defined(amd64):
# words within the jmp_buf structure may not be properly aligned.
let regEnd = sp +% sizeof(registers)
while sp <% regEnd:
gcMark(gch, cast[PPointer](sp)[])
gcMark(gch, cast[PPointer](sp +% sizeof(pointer) div 2)[])
sp = sp +% sizeof(pointer)
# Make sure sp is word-aligned
sp = sp and not (sizeof(pointer) - 1)
# loop unrolled:
while sp <% max - 8*sizeof(pointer):
gcMark(gch, cast[PStackSlice](sp)[0])