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ntdll: Clear the first ~1MB of stack in signal_start_thread. 

Instead of the whole stack.

Stack creation in virtual_alloc_thread_stack and RtlCreateUserStack, as
well as Windows rounding logic, enforce a minimum reserved size of 1MB.

There's a few guard and canary pages used on the bottom, plus a few more
on the top for initial context, and we have to keep a bit of space if we
ever need a stack while doing this, so we clear a bit less than 1MB to
be safe.

Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
This commit is contained in:
Rémi Bernon 2021-03-31 12:23:37 +02:00 committed by Alexandre Julliard
parent 94dcca8a0e
commit 96f5968a65
2 changed files with 5 additions and 8 deletions
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9
dlls/ntdll/signal_i386.c
View File

@ -504,13 +504,12 @@ USHORT WINAPI RtlCaptureStackBackTrace( ULONG skip, ULONG count, PVOID *buffer,
*/
__ASM_GLOBAL_FUNC( signal_start_thread,
"movl 4(%esp),%esi\n\t" /* context */
"leal -12(%esi),%ecx\n\t"
"leal -12(%esi),%edi\n\t"
/* clear the thread stack */
"andl $~0xfff,%ecx\n\t" /* round down to page size */
"movl %fs:8,%edi\n\t" /* NtCurrentTeb()->Tib.StackLimit */
"addl $0x1000,%edi\n\t"
"andl $~0xfff,%edi\n\t" /* round down to page size */
"movl $0xf0000,%ecx\n\t"
"subl %ecx,%edi\n\t"
"movl %edi,%esp\n\t"
"subl %edi,%ecx\n\t"
"xorl %eax,%eax\n\t"
"shrl $2,%ecx\n\t"
"rep; stosl\n\t"

4
dlls/ntdll/signal_x86_64.c
View File

@ -1544,9 +1544,7 @@ __ASM_GLOBAL_FUNC( signal_start_thread,
"movq %rcx,%rbx\n\t" /* context */
/* clear the thread stack */
"andq $~0xfff,%rcx\n\t" /* round down to page size */
"movq %gs:0x30,%rax\n\t"
"movq 0x10(%rax),%rdi\n\t" /* NtCurrentTeb()->Tib.StackLimit */
"addq $0x2000,%rdi\n\t"
"leaq -0xf0000(%rcx),%rdi\n\t"
"movq %rdi,%rsp\n\t"
"subq %rdi,%rcx\n\t"
"xorl %eax,%eax\n\t"