[igt-dev] [PATCH i-g-t] Fix global symbol loading failure in resolve function

[brandon.hong at intel.com]

From: Brandon Hong <brandon.hong at intel.com>

270 out of 284 tests get failed with SIGSEGV on ClearLinux because the ifunc
resolver resolve_half_to_float() tries to call unbound global function
igt_x86_features(). This patch fixes the issue by adding a F16C checking
local function.

Signed-off-by: Brandon Hong <brandon.hong at intel.com>
---
 lib/igt_halffloat.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/lib/igt_halffloat.c b/lib/igt_halffloat.c
index 08ab05fc..fa7ad2e0 100644
--- a/lib/igt_halffloat.c
+++ b/lib/igt_halffloat.c
@@ -24,6 +24,7 @@
 
 #include <assert.h>
 #include <math.h>
+#include <stdbool.h>
 
 #include "igt_halffloat.h"
 #include "igt_x86.h"
@@ -163,6 +164,8 @@ static inline float _half_to_float(uint16_t val)
 }
 
 #if defined(__x86_64__) && !defined(__clang__)
+#include <cpuid.h>
+
 #pragma GCC push_options
 #pragma GCC target("f16c")
 
@@ -182,6 +185,20 @@ static void half_to_float_f16c(const uint16_t *h, float *f, unsigned int num)
 
 #pragma GCC pop_options
 
+static bool f16c_is_supported(void)
+{
+	unsigned max = __get_cpuid_max(0, NULL);
+	unsigned eax, ebx, ecx, edx;
+
+	if (max >= 1) {
+		__cpuid(1, eax, ebx, ecx, edx);
+
+		if (ecx & bit_F16C)
+			return true;
+	}
+	return false;
+}
+
 static void float_to_half(const float *f, uint16_t *h, unsigned int num)
 {
 	for (int i = 0; i < num; i++)
@@ -194,9 +211,10 @@ static void half_to_float(const uint16_t *h, float *f, unsigned int num)
 		f[i] = _half_to_float(h[i]);
 }
 
+
 static void (*resolve_float_to_half(void))(const float *f, uint16_t *h, unsigned int num)
 {
-	if (igt_x86_features() & F16C)
+	if (f16c_is_supported())
 		return float_to_half_f16c;
 
 	return float_to_half;
@@ -207,7 +225,7 @@ void igt_float_to_half(const float *f, uint16_t *h, unsigned int num)
 
 static void (*resolve_half_to_float(void))(const uint16_t *h, float *f, unsigned int num)
 {
-	if (igt_x86_features() & F16C)
+	if (f16c_is_supported())
 		return half_to_float_f16c;
 
 	return half_to_float;
-- 
2.23.0