From 2ed9bf330709e75c2f066f6ec13ece1ecdb4e9db Mon Sep 17 00:00:00 2001
From: Aaron Conole <aconole@redhat.com>
Date: Mon, 2 Apr 2018 14:24:34 -0400
Subject: [PATCH] eal: abstract away the auxiliary vector
Rather than attempting to load the contents of the auxv directly,
prefer to use an exposed API - and if that doesn't exist then attempt
to load the vector. This is because on some systems, when a user
is downgraded, the /proc/self/auxv file retains the old ownership
and permissions. The original method of /proc/self/auxv is retained.
This also removes a potential abort() in the code when compiled with
NDEBUG. A quick parse of the code shows that many (if not all) of
the CPU flag parsing isn't used internally, so it should be okay.
Signed-off-by: Aaron Conole <aconole@redhat.com>
Signed-off-by: Timothy Redaelli <tredaelli@redhat.com>
---
lib/librte_eal/common/arch/arm/rte_cpuflags.c | 20 +----
.../common/arch/ppc_64/rte_cpuflags.c | 15 +---
lib/librte_eal/common/eal_common_cpuflags.c | 79 +++++++++++++++++++
.../common/include/generic/rte_cpuflags.h | 21 +++++
4 files changed, 106 insertions(+), 29 deletions(-)
diff --git a/lib/librte_eal/common/arch/arm/rte_cpuflags.c b/lib/librte_eal/common/arch/arm/rte_cpuflags.c
index 390a19a26..caf3dc83a 100644
--- a/lib/librte_eal/common/arch/arm/rte_cpuflags.c
+++ b/lib/librte_eal/common/arch/arm/rte_cpuflags.c
@@ -105,22 +105,10 @@ const struct feature_entry rte_cpu_feature_table[] = {
static void
rte_cpu_get_features(hwcap_registers_t out)
{
- int auxv_fd;
- _Elfx_auxv_t auxv;
-
- auxv_fd = open("/proc/self/auxv", O_RDONLY);
- assert(auxv_fd != -1);
- while (read(auxv_fd, &auxv, sizeof(auxv)) == sizeof(auxv)) {
- if (auxv.a_type == AT_HWCAP) {
- out[REG_HWCAP] = auxv.a_un.a_val;
- } else if (auxv.a_type == AT_HWCAP2) {
- out[REG_HWCAP2] = auxv.a_un.a_val;
- } else if (auxv.a_type == AT_PLATFORM) {
- if (!strcmp((const char *)auxv.a_un.a_val, PLATFORM_STR))
- out[REG_PLATFORM] = 0x0001;
- }
- }
- close(auxv_fd);
+ out[REG_HWCAP] = rte_cpu_getauxval(AT_HWCAP);
+ out[REG_HWCAP2] = rte_cpu_getauxval(AT_HWCAP2);
+ if (!rte_cpu_strcmp_auxval(AT_PLATFORM, PLATFORM_STR))
+ out[REG_PLATFORM] = 0x0001;
}
/*
diff --git a/lib/librte_eal/common/arch/ppc_64/rte_cpuflags.c b/lib/librte_eal/common/arch/ppc_64/rte_cpuflags.c
index 970a61c5e..e7a82452b 100644
--- a/lib/librte_eal/common/arch/ppc_64/rte_cpuflags.c
+++ b/lib/librte_eal/common/arch/ppc_64/rte_cpuflags.c
@@ -104,19 +104,8 @@ const struct feature_entry rte_cpu_feature_table[] = {
static void
rte_cpu_get_features(hwcap_registers_t out)
{
- int auxv_fd;
- Elf64_auxv_t auxv;
-
- auxv_fd = open("/proc/self/auxv", O_RDONLY);
- assert(auxv_fd != -1);
- while (read(auxv_fd, &auxv,
- sizeof(Elf64_auxv_t)) == sizeof(Elf64_auxv_t)) {
- if (auxv.a_type == AT_HWCAP)
- out[REG_HWCAP] = auxv.a_un.a_val;
- else if (auxv.a_type == AT_HWCAP2)
- out[REG_HWCAP2] = auxv.a_un.a_val;
- }
- close(auxv_fd);
+ out[REG_HWCAP] = rte_cpu_getauxval(AT_HWCAP);
+ out[REG_HWCAP2] = rte_cpu_getauxval(AT_HWCAP2);
}
/*
diff --git a/lib/librte_eal/common/eal_common_cpuflags.c b/lib/librte_eal/common/eal_common_cpuflags.c
index 3a055f7c7..a09667563 100644
--- a/lib/librte_eal/common/eal_common_cpuflags.c
+++ b/lib/librte_eal/common/eal_common_cpuflags.c
@@ -2,11 +2,90 @@
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
+#include <elf.h>
+#include <fcntl.h>
#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
+#if __GLIBC_PREREQ(2, 16)
+#include <sys/auxv.h>
+#define HAS_AUXV 1
+#endif
+#endif
#include <rte_common.h>
#include <rte_cpuflags.h>
+#ifndef HAS_AUXV
+static unsigned long
+getauxval(unsigned long type)
+{
+ errno = ENOTSUP;
+ return 0;
+}
+#endif
+
+#ifdef RTE_ARCH_64
+typedef Elf64_auxv_t Internal_Elfx_auxv_t;
+#else
+typedef Elf32_auxv_t Internal_Elfx_auxv_t;
+#endif
+
+
+/**
+ * Provides a method for retrieving values from the auxiliary vector and
+ * possibly running a string comparison.
+ *
+ * @return Always returns a result. When the result is 0, check errno
+ * to see if an error occurred during processing.
+ */
+static unsigned long
+_rte_cpu_getauxval(unsigned long type, const char *str)
+{
+ unsigned long val;
+
+ errno = 0;
+ val = getauxval(type);
+
+ if (!val && (errno == ENOTSUP || errno == ENOENT)) {
+ int auxv_fd = open("/proc/self/auxv", O_RDONLY);
+ Internal_Elfx_auxv_t auxv;
+
+ if (auxv_fd == -1)
+ return 0;
+
+ errno = ENOENT;
+ while (read(auxv_fd, &auxv, sizeof(auxv)) == sizeof(auxv)) {
+ if (auxv.a_type == type) {
+ errno = 0;
+ val = auxv.a_un.a_val;
+ if (str)
+ val = strcmp((const char *)val, str);
+ break;
+ }
+ }
+ close(auxv_fd);
+ }
+
+ return val;
+}
+
+unsigned long
+rte_cpu_getauxval(unsigned long type)
+{
+ return _rte_cpu_getauxval(type, NULL);
+}
+
+int
+rte_cpu_strcmp_auxval(unsigned long type, const char *str)
+{
+ return _rte_cpu_getauxval(type, str);
+}
+
/**
* Checks if the machine is adequate for running the binary. If it is not, the
* program exits with status 1.
diff --git a/lib/librte_eal/common/include/generic/rte_cpuflags.h b/lib/librte_eal/common/include/generic/rte_cpuflags.h
index 8d31687d8..156ea0029 100644
--- a/lib/librte_eal/common/include/generic/rte_cpuflags.h
+++ b/lib/librte_eal/common/include/generic/rte_cpuflags.h
@@ -64,4 +64,25 @@ rte_cpu_check_supported(void);
int
rte_cpu_is_supported(void);
+/**
+ * This function attempts to retrieve a value from the auxiliary vector.
+ * If it is unsuccessful, the result will be 0, and errno will be set.
+ *
+ * @return A value from the auxiliary vector. When the value is 0, check
+ * errno to determine if an error occurred.
+ */
+unsigned long
+rte_cpu_getauxval(unsigned long type);
+
+/**
+ * This function retrieves a value from the auxiliary vector, and compares it
+ * as a string against the value retrieved.
+ *
+ * @return The result of calling strcmp() against the value retrieved from
+ * the auxiliary vector. When the value is 0 (meaning a match is found),
+ * check errno to determine if an error occurred.
+ */
+int
+rte_cpu_strcmp_auxval(unsigned long type, const char *str);
+
#endif /* _RTE_CPUFLAGS_H_ */
--
2.17.0