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Drop the funky SSE exception test on linux.

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Replace the check for IN_DRI_DRIVER with the appropriate kernel version check
and just disable SSE on older (pre 2.4) kernels.
This commit is contained in:
George Sapountzis
2007-04-06 13:22:41 +03:00
parent 51a894e6eb
commit 663a3e9ba7
1 changed files with 6 additions and 140 deletions
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src/mesa/x86/common_x86.c
+6 -140
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@@ -36,7 +36,7 @@
/* XXX these includes should probably go into imports.h or glheader.h */
#if defined(USE_SSE_ASM) && defined(__linux__)
#include <signal.h>
#include <linux/version.h>
#endif
#if defined(USE_SSE_ASM) && defined(__FreeBSD__)
#include <sys/types.h>
@@ -63,69 +63,14 @@ extern GLuint _ASMAPI _mesa_x86_cpuid_edx(GLuint op);
/*
* We must verify that the Streaming SIMD Extensions are truly supported
* on this processor before we go ahead and hook out the optimized code.
* Unfortunately, the CPUID bit isn't enough, as the OS must set the
* OSFXSR bit in CR4 if it supports the extended FPU save and restore
* required to use SSE. Unfortunately, we can't just go ahead and read
* this register, as only the kernel can do that. Similarly, we must
* verify that the OSXMMEXCPT bit in CR4 has been set by the OS,
* signifying that it supports unmasked SIMD FPU exceptions. If we take
* an unmasked exception and the OS doesn't correctly support them, the
* best we'll get is a SIGILL and the worst we'll get is an infinite
* loop in the signal delivery from the kernel as we can't interact with
* the SIMD FPU state to clear the exception bits. Either way, this is
* not good.
*
* However, I have been told by Alan Cox that all 2.4 (and later) Linux
* kernels provide full SSE support on all processors that expose SSE via
* the CPUID mechanism. It just so happens that this is the exact set of
* kernels supported DRI. Therefore, when building for DRI the funky SSE
* exception test is omitted.
* the CPUID mechanism.
*/
extern void _mesa_test_os_sse_support( void );
extern void _mesa_test_os_sse_exception_support( void );
#if defined(__linux__) && defined(_POSIX_SOURCE) && defined(X86_FXSR_MAGIC) \
&& !defined(IN_DRI_DRIVER)
static void sigill_handler( int signal, struct sigcontext sc )
{
/*message( "SIGILL, " );*/
/* Both the "xorps %%xmm0,%%xmm0" and "divps %xmm0,%%xmm1"
* instructions are 3 bytes long. We must increment the instruction
* pointer manually to avoid repeated execution of the offending
* instruction.
*
* If the SIGILL is caused by a divide-by-zero when unmasked
* exceptions aren't supported, the SIMD FPU status and control
* word will be restored at the end of the test, so we don't need
* to worry about doing it here. Besides, we may not be able to...
*/
sc.eip += 3;
_mesa_x86_cpu_features &= ~(X86_FEATURE_XMM);
}
static void sigfpe_handler( int signal, struct sigcontext sc )
{
/*message( "SIGFPE, " );*/
if ( sc.fpstate->magic != 0xffff ) {
/* Our signal context has the extended FPU state, so reset the
* divide-by-zero exception mask and clear the divide-by-zero
* exception bit.
*/
sc.fpstate->mxcsr |= 0x00000200;
sc.fpstate->mxcsr &= 0xfffffffb;
} else {
/* If we ever get here, we're completely hosed.
*/
/*message( "\n\n" );*/
_mesa_problem( NULL, "SSE enabling test failed badly!" );
}
}
#endif /* __linux__ && _POSIX_SOURCE && X86_FXSR_MAGIC */
#if defined(WIN32)
#ifndef STATUS_FLOAT_MULTIPLE_TRAPS
# define STATUS_FLOAT_MULTIPLE_TRAPS (0xC00002B5L)
@@ -157,92 +102,13 @@ static LONG WINAPI ExceptionFilter(LPEXCEPTION_POINTERS exp)
#endif /* WIN32 */
/* If we're running on a processor that can do SSE, let's see if we
* are allowed to or not. This will catch 2.4.0 or later kernels that
* haven't been configured for a Pentium III but are running on one,
* and RedHat patched 2.2 kernels that have broken exception handling
* support for user space apps that do SSE.
*
* GH: Isn't this just awful?
*/
static void check_os_sse_support( void )
{
#if defined(__linux__) && !defined(IN_DRI_DRIVER)
#if defined(_POSIX_SOURCE) && defined(X86_FXSR_MAGIC)
struct sigaction saved_sigill;
struct sigaction saved_sigfpe;
/* Save the original signal handlers.
*/
sigaction( SIGILL, NULL, &saved_sigill );
sigaction( SIGFPE, NULL, &saved_sigfpe );
signal( SIGILL, (void (*)(int))sigill_handler );
signal( SIGFPE, (void (*)(int))sigfpe_handler );
/* Emulate test for OSFXSR in CR4. The OS will set this bit if it
* supports the extended FPU save and restore required for SSE. If
* we execute an SSE instruction on a PIII and get a SIGILL, the OS
* doesn't support Streaming SIMD Exceptions, even if the processor
* does.
*/
if ( cpu_has_xmm ) {
_mesa_debug(NULL, "Testing OS support for SSE...\n");
_mesa_test_os_sse_support();
if ( cpu_has_xmm ) {
_mesa_debug(NULL, "Yes\n");
} else {
_mesa_debug(NULL, "No\n");
}
}
/* Emulate test for OSXMMEXCPT in CR4. The OS will set this bit if
* it supports unmasked SIMD FPU exceptions. If we unmask the
* exceptions, do a SIMD divide-by-zero and get a SIGILL, the OS
* doesn't support unmasked SIMD FPU exceptions. If we get a SIGFPE
* as expected, we're okay but we need to clean up after it.
*
* Are we being too stringent in our requirement that the OS support
* unmasked exceptions? Certain RedHat 2.2 kernels enable SSE by
* setting CR4.OSFXSR but don't support unmasked exceptions. Win98
* doesn't even support them. We at least know the user-space SSE
* support is good in kernels that do support unmasked exceptions,
* and therefore to be safe I'm going to leave this test in here.
*/
if ( cpu_has_xmm ) {
_mesa_debug(NULL, "Testing OS support for SSE unmasked exceptions...\n");
_mesa_test_os_sse_exception_support();
if ( cpu_has_xmm ) {
_mesa_debug(NULL, "Yes.\n");
} else {
_mesa_debug(NULL, "No!\n");
}
}
/* Restore the original signal handlers.
*/
sigaction( SIGILL, &saved_sigill, NULL );
sigaction( SIGFPE, &saved_sigfpe, NULL );
/* If we've gotten to here and the XMM CPUID bit is still set, we're
* safe to go ahead and hook out the SSE code throughout Mesa.
*/
if ( cpu_has_xmm ) {
_mesa_debug(NULL, "Tests of OS support for SSE passed.\n");
} else {
_mesa_debug(NULL, "Tests of OS support for SSE failed!\n");
}
#else
/* We can't use POSIX signal handling to test the availability of
* SSE, so we disable it by default.
*/
_mesa_debug(NULL, "Cannot test OS support for SSE, disabling to be safe.\n");
#if defined(__linux__)
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,4,0)
_mesa_debug(NULL, "Cannot safely enable SSE on pre-2.4 kernels.\n");
_mesa_x86_cpu_features &= ~(X86_FEATURE_XMM);
#endif /* _POSIX_SOURCE && X86_FXSR_MAGIC */
#endif
#elif defined(__FreeBSD__)
{
int ret, enabled;