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Force stackhot not to be inlined, avoiding the problem described in <https://info.ravenbrook.com/mail/2018/07/11/09-48-49/0/>

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 Change: 194577
This commit is contained in:
Gareth Rees 2018-07-11 10:57:28 +01:00
parent ace93858db
commit 60b4e0639b
3 changed files with 26 additions and 5 deletions
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16
mps/code/config.h
View file

@ -278,8 +278,20 @@
#define ATTRIBUTE_NO_SANITIZE_ADDRESS
#endif
/* Attribute for functions that must not be inlined.
* GCC: <http://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html>
* MSVC: <https://docs.microsoft.com/en-us/cpp/cpp/noinline>
*/
#if defined(MPS_BUILD_GC) || defined(MPS_BUILD_LL)
#define ATTRIBUTE_NOINLINE __attribute__((__noinline__))
#elif defined(MPS_BUILD_MV)
#define ATTRIBUTE_NOINLINE __declspec(noinline)
#else
#define ATTRIBUTE_NOINLINE
#endif
/* Attribute for functions that do not return.
* GCC: <http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html>
* GCC: <http://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html>
* Clang: <http://clang.llvm.org/docs/AttributeReference.html#id1>
*/
#if defined(MPS_BUILD_GC) || defined(MPS_BUILD_LL)
@ -289,7 +301,7 @@
#endif
/* Attribute for functions that may be unused in some build configurations.
* GCC: <http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html>
* GCC: <http://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html>
*
* This attribute must be applied to all Check functions, otherwise
* the RASH variety fails to compile with -Wunused-function. (It

1
mps/code/ss.c
View file

@ -32,6 +32,7 @@ SRCID(ss, "$Id$");
* is a hot stack pointer. See design.mps.ss.sol.stack.hot.
*/
ATTRIBUTE_NOINLINE
void StackHot(void **stackOut)
{
*stackOut = &stackOut;

14
mps/design/stack-scan.txt
View file

@ -138,9 +138,17 @@ being saved by callees.
_`.sol.stack.hot`: We could decode the frame of the function that
invokes ``setjmp()`` from the jump buffer in a platform-specific way,
but we can do something simpler (if more hacky) by calling the stub
function ``StackHot()`` which takes the address of its argument. On
all supported platforms this will yield a pointer that is pretty much
at the hot end of the frame.
function ``StackHot()`` which takes the address of its argument. So
long as this stub function is not inlined into the caller, then on all
supported platforms this yields a pointer that is pretty much at the
hot end of the frame.
_`.sol.stack.hot.noinline`: The reason that ``StackHot()`` must not be
inlined is that after inlining, the compiler might place ``stackOut``
at a colder stack address than the ``StackContextStruct``, causing the
latter not to be scanned. See `mail.gdr.2018-07-11.09-48`_.
.. _mail.gdr.2018-07-11.09-48: https://info.ravenbrook.com/mail/2018/07/11/09-48-49/0/
_`.sol.stack.nest`: We can take care of scanning the jump buffer
itself by storing it in the same stack frame. That way a scan from the