145 lines
4.4 KiB
Diff
145 lines
4.4 KiB
Diff
From a0f53e1dbb3851bb0f0efcfdbd565b05e4be9cac Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Andreas=20M=C3=BCller?= <schnitzeltony@googlemail.com>
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Date: Thu, 23 Aug 2012 18:10:57 +0200
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Subject: [PATCH 1/2] ARM: qemu related workarounds in cpu features detection
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code
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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This was ported from meta-oe's patch [1]. The original pixman patch is found
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at [2].
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[1] http://cgit.openembedded.org/meta-openembedded/tree/meta-oe/recipes-graphics/xorg-lib/pixman-0.26.2/0001-ARM-qemu-related-workarounds-in-cpu-features-detecti.patch
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[2] http://lists.freedesktop.org/archives/pixman/2011-January/000906.html
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Upstream-Status: Inappropriate [other] qemu fix
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Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
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---
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pixman/pixman-arm.c | 82 ++++++++++++++++++++++++++++++++++++++++----------
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1 files changed, 65 insertions(+), 17 deletions(-)
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diff --git a/pixman/pixman-arm.c b/pixman/pixman-arm.c
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index 23374e4..d98bda6 100644
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--- a/pixman/pixman-arm.c
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+++ b/pixman/pixman-arm.c
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@@ -129,16 +129,35 @@ detect_cpu_features (void)
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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+#include <sys/utsname.h>
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#include <fcntl.h>
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#include <string.h>
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#include <elf.h>
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+/*
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+ * The whole CPU capabilities detection is a bit ugly: when running in
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+ * userspace qemu, we see /proc/self/auxv from the host system. To make
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+ * everything even worse, the size of each value is 64-bit when running
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+ * on a 64-bit host system. So the data is totally bogus because we expect
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+ * 32-bit values. As AT_PLATFORM value is used as a pointer, it may cause
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+ * segfault (null pointer dereference on x86-64 host). So in order to be
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+ * on a safe side, we require that AT_PLATFORM value is found only once,
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+ * and it has non-zero value (this is still not totally reliable for a big
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+ * endian 64-bit host system running qemu and may theoretically fail).
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+ */
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+#define ARM_HWCAP_VFP 64
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+#define ARM_HWCAP_IWMMXT 512
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+#define ARM_HWCAP_NEON 4096
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+
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static arm_cpu_features_t
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detect_cpu_features (void)
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{
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arm_cpu_features_t features = 0;
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Elf32_auxv_t aux;
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int fd;
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+ uint32_t hwcap = 0;
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+ const char *plat = NULL;
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+ int plat_cnt = 0;
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fd = open ("/proc/self/auxv", O_RDONLY);
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if (fd >= 0)
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@@ -147,32 +166,61 @@ detect_cpu_features (void)
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{
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if (aux.a_type == AT_HWCAP)
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{
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- uint32_t hwcap = aux.a_un.a_val;
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-
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- /* hardcode these values to avoid depending on specific
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- * versions of the hwcap header, e.g. HWCAP_NEON
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- */
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- if ((hwcap & 64) != 0)
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- features |= ARM_VFP;
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- if ((hwcap & 512) != 0)
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- features |= ARM_IWMMXT;
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- /* this flag is only present on kernel 2.6.29 */
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- if ((hwcap & 4096) != 0)
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- features |= ARM_NEON;
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+ hwcap = aux.a_un.a_val;
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}
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else if (aux.a_type == AT_PLATFORM)
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{
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- const char *plat = (const char*) aux.a_un.a_val;
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-
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- if (strncmp (plat, "v7l", 3) == 0)
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+ plat = (const char*) aux.a_un.a_val;
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+ plat_cnt++;
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+ }
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+ }
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+ close (fd);
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+ if (plat == NULL || plat_cnt != 1 || *plat != 'v')
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+ {
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+ /*
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+ * Something seems to be really wrong, most likely we are
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+ * running under qemu. Let's use machine type from "uname" for
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+ * CPU capabilities detection:
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+ * http://www.mail-archive.com/qemu-devel at nongnu.org/msg22212.html
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+ */
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+ struct utsname u;
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+ hwcap = 0; /* clear hwcap, because it is bogus */
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+ if (uname (&u) == 0)
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+ {
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+ if (strcmp (u.machine, "armv7l") == 0)
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+ {
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features |= (ARM_V7 | ARM_V6);
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- else if (strncmp (plat, "v6l", 3) == 0)
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+ hwcap |= ARM_HWCAP_VFP; /* qemu is supposed to emulate vfp */
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+ hwcap |= ARM_HWCAP_NEON; /* qemu is supposed to emulate neon */
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+ }
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+ else if (strcmp (u.machine, "armv6l") == 0)
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+ {
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features |= ARM_V6;
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+ hwcap |= ARM_HWCAP_VFP; /* qemu is supposed to emulate vfp */
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+ }
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}
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}
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- close (fd);
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+ else if (strncmp (plat, "v7l", 3) == 0)
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+ {
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+ features |= (ARM_V7 | ARM_V6);
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+ }
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+ else if (strncmp (plat, "v6l", 3) == 0)
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+ {
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+ features |= ARM_V6;
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+ }
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}
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+ /* hardcode these values to avoid depending on specific
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+ * versions of the hwcap header, e.g. HWCAP_NEON
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+ */
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+ if ((hwcap & ARM_HWCAP_VFP) != 0)
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+ features |= ARM_VFP;
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+ if ((hwcap & ARM_HWCAP_IWMMXT) != 0)
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+ features |= ARM_IWMMXT;
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+ /* this flag is only present on kernel 2.6.29 */
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+ if ((hwcap & ARM_HWCAP_NEON) != 0)
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+ features |= ARM_NEON;
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+
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return features;
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}
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--
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1.7.6.5
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