diff options
Diffstat (limited to 'private/crt32/startup/i386/chkstk.asm')
| -rw-r--r-- | private/crt32/startup/i386/chkstk.asm | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/private/crt32/startup/i386/chkstk.asm b/private/crt32/startup/i386/chkstk.asm new file mode 100644 index 000000000..bd05942d5 --- /dev/null +++ b/private/crt32/startup/i386/chkstk.asm @@ -0,0 +1,127 @@ + page ,132 + title chkstk - C stack checking routine +;*** +;chkstk.asm - C stack checking routine +; +; Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved. +; +;Purpose: +; Provides support for automatic stack checking in C procedures +; when stack checking is enabled. +; +;Revision History: +; 04-21-87 SKS Added conditional assembly switch for STKHQQ = 0 +; 07-23-87 MAG [1] Added run-time CS:IP error processing for QC +; 08-17-87 JLS [2] Remove all references to DGROUP +; 08-25-87 JLS [3] Shift include files +; 11-13-87 SKS OS/2 Reentrant version, add thread ID check +; 11-18-87 SKS Make STKHQQ an array (oops!) +; 12-14-87 SKS add .286p to allow PUSH immediate value +; 02-19-88 SKS Change minimum bottom limit to STACKSLOP, not 0 +; 06-01-88 PHG Merge DLL and normal versions +; 09-21-88 WAJ initial 386 version +; 10-18-88 JCR Chkstk was trashing bx... not good on 386 +; 06-06-89 JCR 386 mthread support +; 06-20-89 JCR 386: Removed _LOAD_DGROUP code +; 04-06-90 GJF Fixed the copyright. +; 06-21-90 GJF Rewritten to probe pages +; 10-15-90 GJF Restored _end and STKHQQ. +; 03-19-91 GJF Revised to preserve all registers except eax. Note +; this is _rchkstk functionality so there is no longer +; a separate _rchkstk routine. +; 08-01-91 GJF Got rid of _end and STKHQQ, except for Cruiser +; (probably not needed for Cruiser either) [_WIN32_]. +; 09-27-91 JCR Merged Stevewo' changes from NT tree +; +;******************************************************************************* + +.xlist + include cruntime.inc + include msdos.inc +.list + +; size of a page of memory + +_PAGESIZE_ equ 1000h + + +ifdef _CRUISER_ + + .data + +extrn pascal _end:dword ; stack bottom + +ifndef MTHREAD + +public pascal STKHQQ ; used by parasitic heap +STKHQQ dd dataoffset _end+STACKSLOP ; initial value + +endif ;MTHREAD + +endif ;_CRUISER_ + + CODESEG + +page +;*** +;_chkstk - check stack upon procedure entry +; +;Purpose: +; Provide stack checking on procedure entry. Method is to simply probe +; each page of memory required for the stack in descending order. This +; causes the necessary pages of memory to be allocated via the guard +; page scheme, if possible. In the event of failure, the OS raises the +; _XCPT_UNABLE_TO_GROW_STACK exception. +; +; NOTE: Currently, the (EAX < _PAGESIZE_) code path falls through +; to the "lastpage" label of the (EAX >= _PAGESIZE_) code path. This +; is small; a minor speed optimization would be to special case +; this up top. This would avoid the painful save/restore of +; ecx and would shorten the code path by 4-6 instructions. +; +;Entry: +; EAX = size of local frame +; +;Exit: +; ESP = new stackframe, if successful +; +;Uses: +; EAX +; +;Exceptions: +; _XCPT_GUARD_PAGE_VIOLATION - May be raised on a page probe. NEVER TRAP +; THIS!!!! It is used by the OS to grow the +; stack on demand. +; _XCPT_UNABLE_TO_GROW_STACK - The stack cannot be grown. More precisely, +; the attempt by the OS memory manager to +; allocate another guard page in response +; to a _XCPT_GUARD_PAGE_VIOLATION has +; failed. +; +;******************************************************************************* + +labelP _alloca_probe, PUBLIC +labelP _chkstk, PUBLIC + + push ecx ; save ecx + mov ecx,esp ; compute new stack pointer in ecx + add ecx,8 ; correct for return address and saved + ; ecx value +probepages: + cmp eax,_PAGESIZE_ ; more than one page requested? + jb short lastpage ; no + sub ecx,_PAGESIZE_ ; yes, move down a page and... + or dword ptr [ecx],0 ; ...probe it + sub eax,_PAGESIZE_ ; adjust request + jmp probepages + +lastpage: + sub ecx,eax ; move stack down by eax and do a... + or dword ptr [ecx],0 ; ...probe in case a page was crossed + mov eax,esp ; save pointer to current tos + mov esp,ecx ; set the new stack pointer + mov ecx,dword ptr [eax] ; recover ecx + mov eax,dword ptr [eax + 4] ; recover return address + jmp eax ; return + + end |