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[FFmpeg-devel,v2] avutil: use getauxval for CPU capabilities on linux/android ARM

Message ID 20220205061008.92381-1-ffmpeg@tmm1.net
State Accepted
Commit 2f299c0b8b4ab1b549b25ab48aa2adbc9f8718ea
Headers show
Series [FFmpeg-devel,v2] avutil: use getauxval for CPU capabilities on linux/android ARM | expand

Checks

Context Check Description
andriy/make_x86 success Make finished
andriy/make_fate_x86 success Make fate finished
andriy/make_ppc success Make finished
andriy/make_fate_ppc success Make fate finished
andriy/make_aarch64_jetson success Make finished
andriy/make_fate_aarch64_jetson success Make fate finished
andriy/make_fate_armv7_RPi4 success Make fate finished
andriy/make_armv7_RPi4 warning New warnings during build

Commit Message

Aman Karmani Feb. 5, 2022, 6:10 a.m. UTC 
From: Aman Karmani <aman@tmm1.net>

getauxval is faster, and works when procfs is not mounted

note that support on Android was added in 4.4 (API 20)

fixes #6578

Signed-off-by: Aman Karmani <aman@tmm1.net>
---
 configure           |  1 +
 libavutil/arm/cpu.c | 24 +++++++++++++++++++++---
 2 files changed, 22 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/configure b/configure
index 5b19a35f59..d21cfb4cbd 100755
--- a/configure
+++ b/configure
@@ -6265,6 +6265,7 @@  check_func_headers lzo/lzo1x.h lzo1x_999_compress
 check_func_headers mach/mach_time.h mach_absolute_time
 check_func_headers stdlib.h getenv
 check_func_headers sys/stat.h lstat
+check_func_headers sys/auxv.h getauxval
 
 check_func_headers windows.h GetModuleHandle
 check_func_headers windows.h GetProcessAffinityMask
diff --git a/libavutil/arm/cpu.c b/libavutil/arm/cpu.c
index 81e85e2525..c84a655c37 100644
--- a/libavutil/arm/cpu.c
+++ b/libavutil/arm/cpu.c
@@ -38,6 +38,10 @@ 
 #include <string.h>
 #include "libavutil/avstring.h"
 
+#if HAVE_GETAUXVAL
+#include <sys/auxv.h>
+#endif
+
 #define AT_HWCAP        16
 
 /* Relevant HWCAP values from kernel headers */
@@ -48,6 +52,19 @@ 
 #define HWCAP_VFPv3     (1 << 13)
 #define HWCAP_TLS       (1 << 15)
 
+static int get_auxval(uint32_t *hwcap)
+{
+#if HAVE_GETAUXVAL
+    unsigned long ret = getauxval(AT_HWCAP);
+    if (ret == 0)
+        return -1;
+    *hwcap = ret;
+    return 0;
+#else
+    return -1;
+#endif
+}
+
 static int get_hwcap(uint32_t *hwcap)
 {
     struct { uint32_t a_type; uint32_t a_val; } auxv;
@@ -106,9 +123,10 @@  int ff_get_cpu_flags_arm(void)
     int flags = CORE_CPU_FLAGS;
     uint32_t hwcap;
 
-    if (get_hwcap(&hwcap) < 0)
-        if (get_cpuinfo(&hwcap) < 0)
-            return flags;
+    if (get_auxval(&hwcap) < 0)
+        if (get_hwcap(&hwcap) < 0)
+            if (get_cpuinfo(&hwcap) < 0)
+                return flags;
 
 #define check_cap(cap, flag) do {               \
         if (hwcap & HWCAP_ ## cap)              \