From: Aaron Conole Date: Mon, 2 Apr 2018 18:24:34 +0000 (-0400) Subject: eal: abstract away the auxiliary vector X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=2ed9bf330709;p=dpdk.git 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 Signed-off-by: Timothy Redaelli --- diff --git a/lib/librte_eal/common/arch/arm/rte_cpuflags.c b/lib/librte_eal/common/arch/arm/rte_cpuflags.c index 390a19a263..caf3dc83a5 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 970a61c5e7..e7a82452b5 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 3a055f7c73..a09667563e 100644 --- a/lib/librte_eal/common/eal_common_cpuflags.c +++ b/lib/librte_eal/common/eal_common_cpuflags.c @@ -2,11 +2,90 @@ * Copyright(c) 2010-2014 Intel Corporation */ +#include +#include #include +#include +#include +#include +#include + +#if defined(__GLIBC__) && defined(__GLIBC_PREREQ) +#if __GLIBC_PREREQ(2, 16) +#include +#define HAS_AUXV 1 +#endif +#endif #include #include +#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 8d31687d87..156ea00292 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_ */