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x86_64: Handle myfault exceptions when running on alternate signal stack

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x86_64 only:
        * cygtls.cc (san::leave): Restore _my_tls.andreas.
        * cygtls.h (class san):  Add _clemente as in 32 bit case.  Add ret and
        frame members.
        (san::san): Handle _my_tls.andreas as on 32 bit.  Take parameter and
        write it to new member ret.  Store current stack pointer in frame.
        (san::~san): New destructor to restore _my_tls.andreas.
        (__try): Use __l_except address as parameter to san::san.
        * dcrt0.cc (dll_crt0_0): Add myfault_altstack_handler as vectored
        continuation handler.
        * exception.h (myfault_altstack_handler): Declare.
        * exceptions.cc (myfault_altstack_handler): New function.  Explain what
        it's good for.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen
2015-07-07 20:45:06 +02:00
parent 29a1263227
commit 60f10c64aa
5 changed files with 71 additions and 2 deletions
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19
winsup/cygwin/cygtls.h
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@@ -301,11 +301,26 @@ extern _cygtls *_sig_tls;
#ifdef __x86_64__
class san
{
san *_clemente;
uint64_t _cnt;
public:
san () __attribute__ ((always_inline))
DWORD64 ret;
DWORD64 frame;
san (PVOID _ret) __attribute__ ((always_inline))
{
_clemente = _my_tls.andreas;
_my_tls.andreas = this;
_cnt = _my_tls.locals.pathbufs._counters;
/* myfault_altstack_handler needs the current stack pointer and the
address of the _except block to restore the context correctly.
See comment preceeding myfault_altstack_handler in exception.cc. */
ret = (DWORD64) _ret;
__asm__ volatile ("movq %%rsp,%0": "=o" (frame));
}
~san () __attribute__ ((always_inline))
{
_my_tls.andreas = _clemente;
}
/* This is the first thing called in the __except handler. The attribute
"returns_twice" makes sure that GCC disregards any register value set
@@ -363,7 +378,7 @@ public:
{ \
__label__ __l_try, __l_except, __l_endtry; \
__mem_barrier; \
san __sebastian; \
san __sebastian (&&__l_except); \
__asm__ goto ("\n" \
" .seh_handler _ZN9exception7myfaultEP17_EXCEPTION_RECORDPvP8_CONTEXTP19_DISPATCHER_CONTEXT, @except \n" \
" .seh_handlerdata \n" \