diff options
Diffstat (limited to 'gcc/ada/seh_init.c')
| -rw-r--r-- | gcc/ada/seh_init.c | 88 |
1 files changed, 86 insertions, 2 deletions
diff --git a/gcc/ada/seh_init.c b/gcc/ada/seh_init.c index dc353d05c6b..9edd88265aa 100644 --- a/gcc/ada/seh_init.c +++ b/gcc/ada/seh_init.c @@ -59,7 +59,7 @@ extern struct Exception_Data _abort_signal; extern void Raise_From_Signal_Handler (struct Exception_Data *, const char *); -#if defined (_WIN32) && !defined (_WIN64) +#if defined (_WIN32) #include <windows.h> #include <excpt.h> @@ -179,17 +179,100 @@ __gnat_SEH_error_handler (struct _EXCEPTION_RECORD* ExceptionRecord, msg = "unhandled signal"; } +#if ! defined (_WIN64) /* This call is important as it avoids locking the second time we catch a signal. Note that this routine is documented as internal to Windows and should not be used. */ _global_unwind2 (EstablisherFrame); /* Call equivalent to RtlUnwind (EstablisherFrame, NULL, NULL, 0); */ +#endif Raise_From_Signal_Handler (exception, msg); return 0; /* This is never reached, avoid compiler warning */ } +#if defined (_WIN64) +/* On x86_64 windows exception mechanism is no more based on a chained list + of handlers addresses on the stack. Instead unwinding information is used + to retrieve the exception handler (similar to ZCX GCC mechanism). So in + order to register an exception handler we need to put in the final + executable some unwinding information. This information might be present + statically in the image file inside the .pdata section or registered + through RtlAddFunctionTable API. Currently the GCC toolchain does not + generate the .pdata information for each function. As we don't need to + handle SEH exceptions except for signal handling we are registering a + "fake" unwinding data that associate a SEH exception handler to the + complete .text section. As we never return from the handler, the system + does not try to do the final unwinding using the pdata information. The + unwinding is handled by the runtime using either the GNAT SJLJ mechanism + or the ZCX GCC mechanism. + + The current implementation is using the RtlAddFunctionTable. Here is for + information purposes the equivalent using a static .pdata section: + + .section .rdata,"dr" + .align 4 + Lunwind_info: + .byte 9,0,0,0 + .rva ___gnat_SEH_error_handler + .section .pdata,"dr" + .align 4 + .long 0 + .rva etext + .rva Lunwind_info + + Solutions based on SetUnhandledExceptionFilter have been discarded as this + function is mostly disabled on last Windows versions. + Using AddVectoredExceptionHandler should also be discarded as it overrides + all SEH exception handlers that might be present in the program itself and + the loaded DLL (for example it results in unexpected behaviors in the + Win32 subsystem. */ + +typedef struct _UNWIND_INFO { + BYTE VersionAndFlags; + BYTE PrologSize; + BYTE CountOfUnwindCodes; + BYTE FrameRegisterAndOffset; + ULONG AddressOfExceptionHandler; +} UNWIND_INFO,*PUNWIND_INFO; + +static RUNTIME_FUNCTION Table[1]; +static UNWIND_INFO unwind_info[1]; + +#define UNW_VERSION 0x01 +#define UNW_FLAG_EHANDLER 0x08 + +void __gnat_install_SEH_handler (void *eh ATTRIBUTE_UNUSED) +{ + /* Get the end of the text section. */ + extern char etext[] asm("etext"); + /* Get the base of the module. */ + extern char _ImageBase[]; + + /* Current version is always 1 and we are registering an + exception handler. */ + unwind_info[0].VersionAndFlags = UNW_FLAG_EHANDLER | UNW_VERSION; + + /* We don't use the unwinding info so fill the structure with 0 values. */ + unwind_info[0].PrologSize = 0; + unwind_info[0].CountOfUnwindCodes = 0; + unwind_info[0].FrameRegisterAndOffset = 0; + + /* Add the exception handler. */ + unwind_info[0].AddressOfExceptionHandler = + (DWORD)((char *)__gnat_SEH_error_handler - _ImageBase); + + /* Set its scope to the entire program. */ + Table[0].BeginAddress = 0; + Table[0].EndAddress = (DWORD)(etext - _ImageBase); + Table[0].UnwindData = (DWORD)((char *)unwind_info - _ImageBase); + + /* Register the unwind information. */ + RtlAddFunctionTable (Table, 1, (DWORD64)_ImageBase); +} + +#else /* defined (_WIN64) */ /* Install the Win32 SEH exception handler. Note that the caller must have allocated 8 bytes on the stack and pass the pointer to this stack space. This is needed as the SEH exception handler must be on the stack of @@ -220,8 +303,9 @@ __gnat_install_SEH_handler (void *ER) asm volatile ("mov %0,%%fs:(0)": : "r" (ER)); } +#endif -#else /* defined (_WIN32) && !defined (_WIN64) */ +#else /* defined (_WIN32) */ /* For all non Windows targets we provide a dummy SEH install handler. */ void __gnat_install_SEH_handler (void *eh ATTRIBUTE_UNUSED) { |