Max/nunuhara_xsystem4
1
0
Fork 0
mirror of https://github.com/nunuhara/xsystem4.git synced 2026-09-22 23:18:01 +03:00
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #272 from kichikuou/ffi

Browse Source 
ffi: Make HLL calls safe against heap reallocation
This commit is contained in:
Nunuhara Cabbage
2025-09-06 12:30:21 -07:00
committed by GitHub
parent 96a560f6a2 f0e25e53d7
commit 6cada80d34
3 changed files with 16 additions and 30 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/vm/heap.h
-9
View File
@@ -78,15 +78,6 @@ int32_t heap_alloc_string(struct string *s);
void heap_describe_slot(int slot);
/*
* Guarantee `headroom` free slots are available on the heap.
*
* XXX: this is a hack to fix an issue with HLL calls where a pointer into the
* heap can be made invalid by a heap reallocation triggered within the
* body of the HLL function.
*/
void heap_guarantee(unsigned headroom);
#ifdef VM_PRIVATE
extern uint32_t heap_next_seq;
src/ffi.c
+16 -8
View File
@@ -303,13 +303,13 @@ void hll_call(int libno, int fno)
if (!fun->fun)
VM_ERROR("Unimplemented HLL function: %s.%s", ain->libraries[libno].name, f->name);
// XXX: Try to prevent the heap from being reallocated mid-call.
// This only works to the extent that HLL functions can guarantee
// no more than 64 heap allocations occur within the call...
heap_guarantee(64);
void *args[HLL_MAX_ARGS];
void *ptrs[HLL_MAX_ARGS];
// Copy reference arguments to the stack to protect against heap
// reallocation during HLL calls.
void *heap_ptrs[HLL_MAX_ARGS];
int heap_slots[HLL_MAX_ARGS];
for (int i = f->nr_arguments - 1; i >= 0; i--) {
switch (f->arguments[i].type.data) {
case AIN_REF_INT:
@@ -330,7 +330,9 @@ void hll_call(int libno, int fno)
break;
case AIN_REF_STRING:
stack_ptr--;
ptrs[i] = &heap[stack[stack_ptr].i].s;
heap_slots[i] = stack[stack_ptr].i;
heap_ptrs[i] = heap[stack[stack_ptr].i].s;
ptrs[i] = &heap_ptrs[i];
args[i] = &ptrs[i];
break;
case AIN_STRUCT:
@@ -341,7 +343,9 @@ void hll_call(int libno, int fno)
case AIN_REF_STRUCT:
case AIN_REF_ARRAY_TYPE:
stack_ptr--;
ptrs[i] = &heap[stack[stack_ptr].i].page;
heap_slots[i] = stack[stack_ptr].i;
heap_ptrs[i] = heap[stack[stack_ptr].i].page;
ptrs[i] = &heap_ptrs[i];
args[i] = &ptrs[i];
break;
default:
@@ -370,9 +374,13 @@ void hll_call(int libno, int fno)
j++;
break;
case AIN_REF_STRING:
heap[heap_slots[i]].s = heap_ptrs[i];
break;
case AIN_REF_STRUCT:
case AIN_REF_FUNC_TYPE:
case AIN_REF_ARRAY_TYPE:
heap[heap_slots[i]].page = heap_ptrs[i];
break;
case AIN_REF_FUNC_TYPE:
break;
case AIN_ARRAY_TYPE:
// Sys41VM doesn't make a copy when passing an array by value.
src/heap.c
-13
View File
@@ -60,19 +60,6 @@ void heap_grow(size_t new_size)
heap_size = new_size;
}
void heap_guarantee(unsigned headroom)
{
if (heap_size - heap_free_ptr >= headroom)
return;
size_t new_size = heap_size;
while (new_size - heap_free_ptr < headroom) {
new_size += HEAP_ALLOC_STEP;
}
heap_grow(new_size);
}
void heap_init(void)
{
if (!heap) {