[x264-devel] [Git][videolan/x264][master] x86inc: Add stack probing on Windows

[Henrik Gramner]

Henrik Gramner pushed to branch master at VideoLAN / x264


Commits:
b86ae3c6 by Henrik Gramner at 2021-02-11T15:09:43+01:00
x86inc: Add stack probing on Windows

Large stack allocations on Windows need to use stack probing in order
to guarantee that all stack memory is committed before accessing it.
This is done by ensuring that the guard page(s) at the end of the
currently committed pages are touched prior to any pages beyond that.

- - - - -


1 changed file:

- common/x86/x86inc.asm


Changes:

=====================================
common/x86/x86inc.asm
=====================================
@@ -356,6 +356,28 @@ DECLARE_REG_TMP_SIZE 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14
 %define vzeroupper_required (mmsize > 16 && (ARCH_X86_64 == 0 || xmm_regs_used > 16 || notcpuflag(avx512)))
 %define high_mm_regs (16*cpuflag(avx512))
 
+; Large stack allocations on Windows need to use stack probing in order
+; to guarantee that all stack memory is committed before accessing it.
+; This is done by ensuring that the guard page(s) at the end of the
+; currently committed pages are touched prior to any pages beyond that.
+%if WIN64
+    %assign STACK_PROBE_SIZE 8192
+%elifidn __OUTPUT_FORMAT__, win32
+    %assign STACK_PROBE_SIZE 4096
+%else
+    %assign STACK_PROBE_SIZE 0
+%endif
+
+%macro PROBE_STACK 1 ; stack_size
+    %if STACK_PROBE_SIZE
+        %assign %%i STACK_PROBE_SIZE
+        %rep %1 / STACK_PROBE_SIZE
+            mov eax, [rsp-%%i]
+            %assign %%i %%i+STACK_PROBE_SIZE
+        %endrep
+    %endif
+%endmacro
+
 %macro ALLOC_STACK 0-2 0, 0 ; stack_size, n_xmm_regs (for win64 only)
     %ifnum %1
         %if %1 != 0
@@ -376,6 +398,7 @@ DECLARE_REG_TMP_SIZE 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14
             %if required_stack_alignment <= STACK_ALIGNMENT
                 ; maintain the current stack alignment
                 %assign stack_size_padded stack_size + %%pad + ((-%%pad-stack_offset-gprsize) & (STACK_ALIGNMENT-1))
+                PROBE_STACK stack_size_padded
                 SUB rsp, stack_size_padded
             %else
                 %assign %%reg_num (regs_used - 1)
@@ -391,6 +414,7 @@ DECLARE_REG_TMP_SIZE 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14
                     %xdefine rstkm rstk
                 %endif
                 %assign stack_size_padded stack_size + ((%%pad + required_stack_alignment-1) & ~(required_stack_alignment-1))
+                PROBE_STACK stack_size_padded
                 mov rstk, rsp
                 and rsp, ~(required_stack_alignment-1)
                 sub rsp, stack_size_padded



View it on GitLab: https://code.videolan.org/videolan/x264/-/commit/b86ae3c66f51ac9eab5ab7ad09a9d62e67961b8a

-- 
View it on GitLab: https://code.videolan.org/videolan/x264/-/commit/b86ae3c66f51ac9eab5ab7ad09a9d62e67961b8a
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