summaryrefslogtreecommitdiff
path: root/crc
diff options
context:
space:
mode:
authorJens Axboe <jaxboe@fusionio.com>2010-06-29 10:07:13 +0200
committerJens Axboe <jaxboe@fusionio.com>2010-06-29 10:07:13 +0200
commite0ab5f977075ec2f8ad42378c95eb800a611f0ef (patch)
tree1afaed78eb34a9fed4482f0783293e2a9424264c /crc
parent10accd7cf68af21ef4831528626a75ba7a06ce81 (diff)
crc32c-intel: replace SIGILL approach with cpuid
Some operating systems log illegal instructions, lets try and be a bit nicer and use cpuid to identify the presence of SSE4.2 which is needed to support the hw crc32c instruction. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'crc')
-rw-r--r--crc/crc32c-intel.c43
1 files changed, 18 insertions, 25 deletions
diff --git a/crc/crc32c-intel.c b/crc/crc32c-intel.c
index fc106fa..77d6df4 100644
--- a/crc/crc32c-intel.c
+++ b/crc/crc32c-intel.c
@@ -74,37 +74,30 @@ uint32_t crc32c_intel(unsigned char const *data, unsigned long length)
return crc;
}
-static void sig_ill(int sig)
+static void do_cpuid(unsigned int *eax, unsigned int *ebx, unsigned int *ecx,
+ unsigned int *edx)
{
-}
-
-static void crc32c_test(void)
-{
- unsigned char buf[4] = { 1, 2, 3, 4 };
- struct sigaction act;
-
- /*
- * Check if hw accelerated crc32c is available
- */
- memset(&act, 0, sizeof(act));
- act.sa_handler = sig_ill;
- act.sa_flags = SA_RESETHAND;
- sigaction(SIGILL, &act, NULL);
-
- (void) crc32c_intel(buf, sizeof(buf));
+ int id = *eax;
+
+ asm("movl %4, %%eax;"
+ "cpuid;"
+ "movl %%eax, %0;"
+ "movl %%ebx, %1;"
+ "movl %%ecx, %2;"
+ "movl %%edx, %3;"
+ : "=r" (*eax), "=r" (*ebx), "=r" (*ecx), "=r" (*edx)
+ : "r" (id)
+ : "eax", "ebx", "ecx", "edx");
}
int crc32c_intel_works(void)
{
- if (!fork()) {
- crc32c_test();
- exit(0);
- } else {
- int status;
+ unsigned int eax, ebx, ecx, edx;
- wait(&status);
- return !WIFSIGNALED(status);
- }
+ eax = 1;
+
+ do_cpuid(&eax, &ebx, &ecx, &edx);
+ return (ecx & (1 << 20)) != 0;
}
#endif /* ARCH_HAVE_SSE */