From: Siarhei Siamashka <[email protected]>
---
pixman/pixman-cpu.c | 67 +++++++++++++++++++++++++++++++++++++++++---------
1 files changed, 55 insertions(+), 12 deletions(-)
diff --git a/pixman/pixman-cpu.c b/pixman/pixman-cpu.c
index 70253d1..06ca69d 100644
--- a/pixman/pixman-cpu.c
+++ b/pixman/pixman-cpu.c
@@ -251,6 +251,7 @@ pixman_have_arm_neon (void)
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
+#include <sys/utsname.h>
#include <fcntl.h>
#include <string.h>
#include <elf.h>
@@ -262,11 +263,25 @@ static pixman_bool_t arm_has_neon = FALSE;
static pixman_bool_t arm_has_iwmmxt = FALSE;
static pixman_bool_t arm_tests_initialized = FALSE;
+/*
+ * The whole CPU capabilities detection is a bit ugly: when running in
+ * userspace qemu, we see /proc/self/auxv from the host system. To make
+ * everything even worse, the size of each value is 64-bit when running
+ * on a 64-bit host system. So the data is totally bogus because we expect
+ * 32-bit values. As AT_PLATFORM value is used as a pointer, it may cause
+ * segfault (null pointer dereference on x86-64 host). So in order to be
+ * on a safe side, we require that AT_PLATFORM value is found only once,
+ * and it has non-zero value (this is still not totally reliable for a big
+ * endian 64-bit host system running qemu and may theoretically fail).
+ */
static void
pixman_arm_read_auxv ()
{
int fd;
Elf32_auxv_t aux;
+ uint32_t hwcap = 0;
+ const char *plat = NULL;
+ int plat_cnt = 0;
fd = open ("/proc/self/auxv", O_RDONLY);
if (fd >= 0)
@@ -275,32 +290,60 @@ pixman_arm_read_auxv ()
{
if (aux.a_type == AT_HWCAP)
{
- uint32_t hwcap = aux.a_un.a_val;
- /* hardcode these values to avoid depending on specific
- * versions of the hwcap header, e.g. HWCAP_NEON
- */
- arm_has_vfp = (hwcap & 64) != 0;
- arm_has_iwmmxt = (hwcap & 512) != 0;
- /* this flag is only present on kernel 2.6.29 */
- arm_has_neon = (hwcap & 4096) != 0;
+ hwcap = aux.a_un.a_val;
}
else if (aux.a_type == AT_PLATFORM)
{
- const char *plat = (const char*) aux.a_un.a_val;
- if (strncmp (plat, "v7l", 3) == 0)
+ plat = (const char*) aux.a_un.a_val;
+ plat_cnt++;
+ }
+ }
+ close (fd);
+
+ if (plat == NULL || plat_cnt != 1 || *plat != 'v')
+ {
+ /*
+ * Something seems to be really wrong, most likely we are
+ * running under qemu. Let's use machine type from "uname" for
+ * CPU capabilities detection:
+ * http://www.mail-archive.com/[email protected]/msg22212.html
+ */
+ struct utsname u;
+ hwcap = 0; /* clear hwcap, because it is bogus */
+ if (uname (&u) == 0)
+ {
+ if (strcmp (u.machine, "armv7l") == 0)
{
arm_has_v7 = TRUE;
arm_has_v6 = TRUE;
+ hwcap |= 64; /* qemu is supposed to emulate vfp */
+ hwcap |= 4096; /* qemu is supposed to emulate neon */
}
- else if (strncmp (plat, "v6l", 3) == 0)
+ else if (strcmp (u.machine, "armv6l") == 0)
{
arm_has_v6 = TRUE;
+ hwcap |= 64; /* qemu is supposed to emulate vfp */
}
}
}
- close (fd);
+ else if (strncmp (plat, "v7l", 3) == 0)
+ {
+ arm_has_v7 = TRUE;
+ arm_has_v6 = TRUE;
+ }
+ else if (strncmp (plat, "v6l", 3) == 0)
+ {
+ arm_has_v6 = TRUE;
+ }
}
+ /* hardcode these values to avoid depending on specific
+ * versions of the hwcap header, e.g. HWCAP_NEON
+ */
+ arm_has_vfp = (hwcap & 64) != 0;
+ arm_has_iwmmxt = (hwcap & 512) != 0;
+ arm_has_neon = (hwcap & 4096) != 0;
+
arm_tests_initialized = TRUE;
}
--
1.7.2.2
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