[dpdk-dev] [RFC UNTESTED PATCH] eal_common_cpuflags: Fix %rbx corruption, and simplify the code
Neil Horman
nhorman at tuxdriver.com
Thu Mar 20 17:39:21 CET 2014
On Thu, Mar 20, 2014 at 08:53:50AM -0700, H. Peter Anvin wrote:
> Neil Horman reported that on x86-64 the upper half of %rbx would get
> clobbered when the code was compiled PIC or PIE, because the
> i386-specific code to preserve %ebx was incorrectly compiled.
>
> However, the code is really way more complex than it needs to be. For
> one thing, the CPUID instruction only needs %eax (leaf) and %ecx
> (subleaf) as parameters, and since we are testing for bits, we might
> as well list the bits explicitly. Furthermore, we can use an array
> rather than doing a switch statement inside a structure.
>
> Reported-by: Neil Horman <nhorman at tuxdriver.com>
> Signed-off-by: H. Peter Anvin <hpa at linux.intel.com>
Acked-by: Neil Horman <nhorman at tuxdriver.com>
> ---
> lib/librte_eal/common/eal_common_cpuflags.c | 272 +++++++++++++---------------
> 1 file changed, 121 insertions(+), 151 deletions(-)
>
> diff --git a/lib/librte_eal/common/eal_common_cpuflags.c b/lib/librte_eal/common/eal_common_cpuflags.c
> index 1ebf78cc2a48..bf66ad9d94ec 100644
> --- a/lib/librte_eal/common/eal_common_cpuflags.c
> +++ b/lib/librte_eal/common/eal_common_cpuflags.c
> @@ -54,21 +54,12 @@
> */
> enum cpu_register_t {
> REG_EAX = 0,
> - REG_EBX,
> REG_ECX,
> REG_EDX,
> + REG_EBX,
> };
>
> -/**
> - * Parameters for CPUID instruction
> - */
> -struct cpuid_parameters_t {
> - uint32_t eax;
> - uint32_t ebx;
> - uint32_t ecx;
> - uint32_t edx;
> - enum cpu_register_t return_register;
> -};
> +typedef uint32_t cpuid_registers_t[4];
>
> #define CPU_FLAG_NAME_MAX_LEN 64
>
> @@ -78,8 +69,10 @@ struct cpuid_parameters_t {
> struct feature_entry {
> enum rte_cpu_flag_t feature; /**< feature name */
> char name[CPU_FLAG_NAME_MAX_LEN]; /**< String for printing */
> - struct cpuid_parameters_t params; /**< cpuid parameters */
> - uint32_t feature_mask; /**< bitmask for feature */
> + uint32_t leaf; /**< cpuid leaf */
> + uint32_t subleaf; /**< cpuid subleaf */
> + uint32_t reg; /**< cpuid register */
> + uint32_t bit; /**< cpuid register bit */
> };
>
> #define FEAT_DEF(f) RTE_CPUFLAG_##f, #f
> @@ -88,97 +81,97 @@ struct feature_entry {
> * An array that holds feature entries
> */
> static const struct feature_entry cpu_feature_table[] = {
> - {FEAT_DEF(SSE3), {0x1, 0, 0, 0, REG_ECX}, 0x00000001},
> - {FEAT_DEF(PCLMULQDQ), {0x1, 0, 0, 0, REG_ECX}, 0x00000002},
> - {FEAT_DEF(DTES64), {0x1, 0, 0, 0, REG_ECX}, 0x00000004},
> - {FEAT_DEF(MONITOR), {0x1, 0, 0, 0, REG_ECX}, 0x00000008},
> - {FEAT_DEF(DS_CPL), {0x1, 0, 0, 0, REG_ECX}, 0x00000010},
> - {FEAT_DEF(VMX), {0x1, 0, 0, 0, REG_ECX}, 0x00000020},
> - {FEAT_DEF(SMX), {0x1, 0, 0, 0, REG_ECX}, 0x00000040},
> - {FEAT_DEF(EIST), {0x1, 0, 0, 0, REG_ECX}, 0x00000080},
> - {FEAT_DEF(TM2), {0x1, 0, 0, 0, REG_ECX}, 0x00000100},
> - {FEAT_DEF(SSSE3), {0x1, 0, 0, 0, REG_ECX}, 0x00000200},
> - {FEAT_DEF(CNXT_ID), {0x1, 0, 0, 0, REG_ECX}, 0x00000400},
> - {FEAT_DEF(FMA), {0x1, 0, 0, 0, REG_ECX}, 0x00001000},
> - {FEAT_DEF(CMPXCHG16B), {0x1, 0, 0, 0, REG_ECX}, 0x00002000},
> - {FEAT_DEF(XTPR), {0x1, 0, 0, 0, REG_ECX}, 0x00004000},
> - {FEAT_DEF(PDCM), {0x1, 0, 0, 0, REG_ECX}, 0x00008000},
> - {FEAT_DEF(PCID), {0x1, 0, 0, 0, REG_ECX}, 0x00020000},
> - {FEAT_DEF(DCA), {0x1, 0, 0, 0, REG_ECX}, 0x00040000},
> - {FEAT_DEF(SSE4_1), {0x1, 0, 0, 0, REG_ECX}, 0x00080000},
> - {FEAT_DEF(SSE4_2), {0x1, 0, 0, 0, REG_ECX}, 0x00100000},
> - {FEAT_DEF(X2APIC), {0x1, 0, 0, 0, REG_ECX}, 0x00200000},
> - {FEAT_DEF(MOVBE), {0x1, 0, 0, 0, REG_ECX}, 0x00400000},
> - {FEAT_DEF(POPCNT), {0x1, 0, 0, 0, REG_ECX}, 0x00800000},
> - {FEAT_DEF(TSC_DEADLINE), {0x1, 0, 0, 0, REG_ECX}, 0x01000000},
> - {FEAT_DEF(AES), {0x1, 0, 0, 0, REG_ECX}, 0x02000000},
> - {FEAT_DEF(XSAVE), {0x1, 0, 0, 0, REG_ECX}, 0x04000000},
> - {FEAT_DEF(OSXSAVE), {0x1, 0, 0, 0, REG_ECX}, 0x08000000},
> - {FEAT_DEF(AVX), {0x1, 0, 0, 0, REG_ECX}, 0x10000000},
> - {FEAT_DEF(F16C), {0x1, 0, 0, 0, REG_ECX}, 0x20000000},
> - {FEAT_DEF(RDRAND), {0x1, 0, 0, 0, REG_ECX}, 0x40000000},
> -
> - {FEAT_DEF(FPU), {0x1, 0, 0, 0, REG_EDX}, 0x00000001},
> - {FEAT_DEF(VME), {0x1, 0, 0, 0, REG_EDX}, 0x00000002},
> - {FEAT_DEF(DE), {0x1, 0, 0, 0, REG_EDX}, 0x00000004},
> - {FEAT_DEF(PSE), {0x1, 0, 0, 0, REG_EDX}, 0x00000008},
> - {FEAT_DEF(TSC), {0x1, 0, 0, 0, REG_EDX}, 0x00000010},
> - {FEAT_DEF(MSR), {0x1, 0, 0, 0, REG_EDX}, 0x00000020},
> - {FEAT_DEF(PAE), {0x1, 0, 0, 0, REG_EDX}, 0x00000040},
> - {FEAT_DEF(MCE), {0x1, 0, 0, 0, REG_EDX}, 0x00000080},
> - {FEAT_DEF(CX8), {0x1, 0, 0, 0, REG_EDX}, 0x00000100},
> - {FEAT_DEF(APIC), {0x1, 0, 0, 0, REG_EDX}, 0x00000200},
> - {FEAT_DEF(SEP), {0x1, 0, 0, 0, REG_EDX}, 0x00000800},
> - {FEAT_DEF(MTRR), {0x1, 0, 0, 0, REG_EDX}, 0x00001000},
> - {FEAT_DEF(PGE), {0x1, 0, 0, 0, REG_EDX}, 0x00002000},
> - {FEAT_DEF(MCA), {0x1, 0, 0, 0, REG_EDX}, 0x00004000},
> - {FEAT_DEF(CMOV), {0x1, 0, 0, 0, REG_EDX}, 0x00008000},
> - {FEAT_DEF(PAT), {0x1, 0, 0, 0, REG_EDX}, 0x00010000},
> - {FEAT_DEF(PSE36), {0x1, 0, 0, 0, REG_EDX}, 0x00020000},
> - {FEAT_DEF(PSN), {0x1, 0, 0, 0, REG_EDX}, 0x00040000},
> - {FEAT_DEF(CLFSH), {0x1, 0, 0, 0, REG_EDX}, 0x00080000},
> - {FEAT_DEF(DS), {0x1, 0, 0, 0, REG_EDX}, 0x00200000},
> - {FEAT_DEF(ACPI), {0x1, 0, 0, 0, REG_EDX}, 0x00400000},
> - {FEAT_DEF(MMX), {0x1, 0, 0, 0, REG_EDX}, 0x00800000},
> - {FEAT_DEF(FXSR), {0x1, 0, 0, 0, REG_EDX}, 0x01000000},
> - {FEAT_DEF(SSE), {0x1, 0, 0, 0, REG_EDX}, 0x02000000},
> - {FEAT_DEF(SSE2), {0x1, 0, 0, 0, REG_EDX}, 0x04000000},
> - {FEAT_DEF(SS), {0x1, 0, 0, 0, REG_EDX}, 0x08000000},
> - {FEAT_DEF(HTT), {0x1, 0, 0, 0, REG_EDX}, 0x10000000},
> - {FEAT_DEF(TM), {0x1, 0, 0, 0, REG_EDX}, 0x20000000},
> - {FEAT_DEF(PBE), {0x1, 0, 0, 0, REG_EDX}, 0x80000000},
> -
> - {FEAT_DEF(DIGTEMP), {0x6, 0, 0, 0, REG_EAX}, 0x00000001},
> - {FEAT_DEF(TRBOBST), {0x6, 0, 0, 0, REG_EAX}, 0x00000002},
> - {FEAT_DEF(ARAT), {0x6, 0, 0, 0, REG_EAX}, 0x00000004},
> - {FEAT_DEF(PLN), {0x6, 0, 0, 0, REG_EAX}, 0x00000010},
> - {FEAT_DEF(ECMD), {0x6, 0, 0, 0, REG_EAX}, 0x00000020},
> - {FEAT_DEF(PTM), {0x6, 0, 0, 0, REG_EAX}, 0x00000040},
> -
> - {FEAT_DEF(MPERF_APERF_MSR), {0x6, 0, 0, 0, REG_ECX}, 0x00000001},
> - {FEAT_DEF(ACNT2), {0x6, 0, 0, 0, REG_ECX}, 0x00000002},
> - {FEAT_DEF(ENERGY_EFF), {0x6, 0, 0, 0, REG_ECX}, 0x00000008},
> -
> - {FEAT_DEF(FSGSBASE), {0x7, 0, 0, 0, REG_EBX}, 0x00000001},
> - {FEAT_DEF(BMI1), {0x7, 0, 0, 0, REG_EBX}, 0x00000004},
> - {FEAT_DEF(HLE), {0x7, 0, 0, 0, REG_EBX}, 0x00000010},
> - {FEAT_DEF(AVX2), {0x7, 0, 0, 0, REG_EBX}, 0x00000020},
> - {FEAT_DEF(SMEP), {0x7, 0, 0, 0, REG_EBX}, 0x00000040},
> - {FEAT_DEF(BMI2), {0x7, 0, 0, 0, REG_EBX}, 0x00000080},
> - {FEAT_DEF(ERMS), {0x7, 0, 0, 0, REG_EBX}, 0x00000100},
> - {FEAT_DEF(INVPCID), {0x7, 0, 0, 0, REG_EBX}, 0x00000400},
> - {FEAT_DEF(RTM), {0x7, 0, 0, 0, REG_EBX}, 0x00000800},
> -
> - {FEAT_DEF(LAHF_SAHF), {0x80000001, 0, 0, 0, REG_ECX}, 0x00000001},
> - {FEAT_DEF(LZCNT), {0x80000001, 0, 0, 0, REG_ECX}, 0x00000010},
> -
> - {FEAT_DEF(SYSCALL), {0x80000001, 0, 0, 0, REG_EDX}, 0x00000800},
> - {FEAT_DEF(XD), {0x80000001, 0, 0, 0, REG_EDX}, 0x00100000},
> - {FEAT_DEF(1GB_PG), {0x80000001, 0, 0, 0, REG_EDX}, 0x04000000},
> - {FEAT_DEF(RDTSCP), {0x80000001, 0, 0, 0, REG_EDX}, 0x08000000},
> - {FEAT_DEF(EM64T), {0x80000001, 0, 0, 0, REG_EDX}, 0x20000000},
> -
> - {FEAT_DEF(INVTSC), {0x80000007, 0, 0, 0, REG_EDX}, 0x00000100},
> + {FEAT_DEF(SSE3), 0x00000001, 0, REG_ECX, 0},
> + {FEAT_DEF(PCLMULQDQ), 0x00000001, 0, REG_ECX, 1},
> + {FEAT_DEF(DTES64), 0x00000001, 0, REG_ECX, 2},
> + {FEAT_DEF(MONITOR), 0x00000001, 0, REG_ECX, 3},
> + {FEAT_DEF(DS_CPL), 0x00000001, 0, REG_ECX, 4},
> + {FEAT_DEF(VMX), 0x00000001, 0, REG_ECX, 5},
> + {FEAT_DEF(SMX), 0x00000001, 0, REG_ECX, 6},
> + {FEAT_DEF(EIST), 0x00000001, 0, REG_ECX, 7},
> + {FEAT_DEF(TM2), 0x00000001, 0, REG_ECX, 8},
> + {FEAT_DEF(SSSE3), 0x00000001, 0, REG_ECX, 9},
> + {FEAT_DEF(CNXT_ID), 0x00000001, 0, REG_ECX, 10},
> + {FEAT_DEF(FMA), 0x00000001, 0, REG_ECX, 12},
> + {FEAT_DEF(CMPXCHG16B), 0x00000001, 0, REG_ECX, 13},
> + {FEAT_DEF(XTPR), 0x00000001, 0, REG_ECX, 14},
> + {FEAT_DEF(PDCM), 0x00000001, 0, REG_ECX, 15},
> + {FEAT_DEF(PCID), 0x00000001, 0, REG_ECX, 17},
> + {FEAT_DEF(DCA), 0x00000001, 0, REG_ECX, 18},
> + {FEAT_DEF(SSE4_1), 0x00000001, 0, REG_ECX, 19},
> + {FEAT_DEF(SSE4_2), 0x00000001, 0, REG_ECX, 20},
> + {FEAT_DEF(X2APIC), 0x00000001, 0, REG_ECX, 21},
> + {FEAT_DEF(MOVBE), 0x00000001, 0, REG_ECX, 22},
> + {FEAT_DEF(POPCNT), 0x00000001, 0, REG_ECX, 23},
> + {FEAT_DEF(TSC_DEADLINE), 0x00000001, 0, REG_ECX, 24},
> + {FEAT_DEF(AES), 0x00000001, 0, REG_ECX, 25},
> + {FEAT_DEF(XSAVE), 0x00000001, 0, REG_ECX, 26},
> + {FEAT_DEF(OSXSAVE), 0x00000001, 0, REG_ECX, 27},
> + {FEAT_DEF(AVX), 0x00000001, 0, REG_ECX, 28},
> + {FEAT_DEF(F16C), 0x00000001, 0, REG_ECX, 29},
> + {FEAT_DEF(RDRAND), 0x00000001, 0, REG_ECX, 30},
> +
> + {FEAT_DEF(FPU), 0x00000001, 0, REG_EDX, 0},
> + {FEAT_DEF(VME), 0x00000001, 0, REG_EDX, 1},
> + {FEAT_DEF(DE), 0x00000001, 0, REG_EDX, 2},
> + {FEAT_DEF(PSE), 0x00000001, 0, REG_EDX, 3},
> + {FEAT_DEF(TSC), 0x00000001, 0, REG_EDX, 4},
> + {FEAT_DEF(MSR), 0x00000001, 0, REG_EDX, 5},
> + {FEAT_DEF(PAE), 0x00000001, 0, REG_EDX, 6},
> + {FEAT_DEF(MCE), 0x00000001, 0, REG_EDX, 7},
> + {FEAT_DEF(CX8), 0x00000001, 0, REG_EDX, 8},
> + {FEAT_DEF(APIC), 0x00000001, 0, REG_EDX, 9},
> + {FEAT_DEF(SEP), 0x00000001, 0, REG_EDX, 11},
> + {FEAT_DEF(MTRR), 0x00000001, 0, REG_EDX, 12},
> + {FEAT_DEF(PGE), 0x00000001, 0, REG_EDX, 13},
> + {FEAT_DEF(MCA), 0x00000001, 0, REG_EDX, 14},
> + {FEAT_DEF(CMOV), 0x00000001, 0, REG_EDX, 15},
> + {FEAT_DEF(PAT), 0x00000001, 0, REG_EDX, 16},
> + {FEAT_DEF(PSE36), 0x00000001, 0, REG_EDX, 17},
> + {FEAT_DEF(PSN), 0x00000001, 0, REG_EDX, 18},
> + {FEAT_DEF(CLFSH), 0x00000001, 0, REG_EDX, 19},
> + {FEAT_DEF(DS), 0x00000001, 0, REG_EDX, 21},
> + {FEAT_DEF(ACPI), 0x00000001, 0, REG_EDX, 22},
> + {FEAT_DEF(MMX), 0x00000001, 0, REG_EDX, 23},
> + {FEAT_DEF(FXSR), 0x00000001, 0, REG_EDX, 24},
> + {FEAT_DEF(SSE), 0x00000001, 0, REG_EDX, 25},
> + {FEAT_DEF(SSE2), 0x00000001, 0, REG_EDX, 26},
> + {FEAT_DEF(SS), 0x00000001, 0, REG_EDX, 27},
> + {FEAT_DEF(HTT), 0x00000001, 0, REG_EDX, 28},
> + {FEAT_DEF(TM), 0x00000001, 0, REG_EDX, 29},
> + {FEAT_DEF(PBE), 0x00000001, 0, REG_EDX, 31},
> +
> + {FEAT_DEF(DIGTEMP), 0x00000006, 0, REG_EAX, 0},
> + {FEAT_DEF(TRBOBST), 0x00000006, 0, REG_EAX, 1},
> + {FEAT_DEF(ARAT), 0x00000006, 0, REG_EAX, 2},
> + {FEAT_DEF(PLN), 0x00000006, 0, REG_EAX, 4},
> + {FEAT_DEF(ECMD), 0x00000006, 0, REG_EAX, 5},
> + {FEAT_DEF(PTM), 0x00000006, 0, REG_EAX, 6},
> +
> + {FEAT_DEF(MPERF_APERF_MSR), 0x00000006, 0, REG_ECX, 0},
> + {FEAT_DEF(ACNT2), 0x00000006, 0, REG_ECX, 1},
> + {FEAT_DEF(ENERGY_EFF), 0x00000006, 0, REG_ECX, 3},
> +
> + {FEAT_DEF(FSGSBASE), 0x00000007, 0, REG_EBX, 0},
> + {FEAT_DEF(BMI1), 0x00000007, 0, REG_EBX, 2},
> + {FEAT_DEF(HLE), 0x00000007, 0, REG_EBX, 4},
> + {FEAT_DEF(AVX2), 0x00000007, 0, REG_EBX, 5},
> + {FEAT_DEF(SMEP), 0x00000007, 0, REG_EBX, 6},
> + {FEAT_DEF(BMI2), 0x00000007, 0, REG_EBX, 7},
> + {FEAT_DEF(ERMS), 0x00000007, 0, REG_EBX, 8},
> + {FEAT_DEF(INVPCID), 0x00000007, 0, REG_EBX, 10},
> + {FEAT_DEF(RTM), 0x00000007, 0, REG_EBX, 11},
> +
> + {FEAT_DEF(LAHF_SAHF), 0x80000001, 0, REG_ECX, 0},
> + {FEAT_DEF(LZCNT), 0x80000001, 0, REG_ECX, 4},
> +
> + {FEAT_DEF(SYSCALL), 0x80000001, 0, REG_EDX, 11},
> + {FEAT_DEF(XD), 0x80000001, 0, REG_EDX, 20},
> + {FEAT_DEF(1GB_PG), 0x80000001, 0, REG_EDX, 26},
> + {FEAT_DEF(RDTSCP), 0x80000001, 0, REG_EDX, 27},
> + {FEAT_DEF(EM64T), 0x80000001, 0, REG_EDX, 29},
> +
> + {FEAT_DEF(INVTSC), 0x80000007, 0, REG_EDX, 8},
> };
>
> /*
> @@ -187,51 +180,25 @@ static const struct feature_entry cpu_feature_table[] = {
> * This function, when compiled with GCC, will generate architecture-neutral
> * code, as per GCC manual.
> */
> -static inline int
> -rte_cpu_get_features(struct cpuid_parameters_t params)
> +static inline void
> +rte_cpu_get_features(uint32_t leaf, uint32_t subleaf, cpuid_registers_t *out)
> {
> - int eax, ebx, ecx, edx; /* registers */
> -
> -#ifndef __PIC__
> - asm volatile ("cpuid"
> - /* output */
> - : "=a" (eax),
> - "=b" (ebx),
> - "=c" (ecx),
> - "=d" (edx)
> - /* input */
> - : "a" (params.eax),
> - "b" (params.ebx),
> - "c" (params.ecx),
> - "d" (params.edx));
> +#if defined(__i386__) && defined(__PIC__)
> + /* %ebx is a forbidden register if we compile with -fPIC or -fPIE */
> + asm volatile("movl %%ebx,%0 ; cpuid ; xchgl %%ebx,%0"
> + : "=r" (out[REG_EBX]),
> + "=a" (out[REG_EAX]),
> + "=c" (out[REG_ECX]),
> + "=d" (out[REG_EDX])
> + : "a" (leaf), "c" (subleaf));
> #else
> - asm volatile (
> - "mov %%ebx, %%edi\n"
> - "cpuid\n"
> - "xchgl %%ebx, %%edi;\n"
> - : "=a" (eax),
> - "=D" (ebx),
> - "=c" (ecx),
> - "=d" (edx)
> - /* input */
> - : "a" (params.eax),
> - "D" (params.ebx),
> - "c" (params.ecx),
> - "d" (params.edx));
> + asm volatile("cpuid"
> + : "=b" (out[REG_EBX]),
> + "=a" (out[REG_EAX]),
> + "=c" (out[REG_ECX]),
> + "=d" (out[REG_EDX])
> + : "a" (leaf), "c" (subleaf));
> #endif
> -
> - switch (params.return_register) {
> - case REG_EAX:
> - return eax;
> - case REG_EBX:
> - return ebx;
> - case REG_ECX:
> - return ecx;
> - case REG_EDX:
> - return edx;
> - default:
> - return 0;
> - }
> }
>
> /*
> @@ -240,17 +207,20 @@ rte_cpu_get_features(struct cpuid_parameters_t params)
> int
> rte_cpu_get_flag_enabled(enum rte_cpu_flag_t feature)
> {
> - int value;
> + const struct feature_entry *feat;
> + cpu_registers_t regs;
>
> if (feature >= RTE_CPUFLAG_NUMFLAGS)
> /* Flag does not match anything in the feature tables */
> return -ENOENT;
>
> - /* get value of the register containing the desired feature */
> - value = rte_cpu_get_features(cpu_feature_table[feature].params);
> + feat = &cpu_feature_table[feature];
> +
> + /* get the cpuid leaf containing the desired feature */
> + rte_cpu_get_features(feat->leaf, feat->subleaf, ®s);
>
> /* check if the feature is enabled */
> - return (cpu_feature_table[feature].feature_mask & value) > 0;
> + return (regs[feat->reg] >> feat->bit) & 1;
> }
>
> /**
> @@ -273,7 +243,7 @@ rte_cpu_check_supported(void)
> unsigned i;
>
> for (i = 0; i < sizeof(compile_time_flags)/sizeof(compile_time_flags[0]); i++)
> - if (rte_cpu_get_flag_enabled(compile_time_flags[i]) < 1) {
> + if (!rte_cpu_get_flag_enabled(compile_time_flags[i])) {
> fprintf(stderr,
> "ERROR: This system does not support \"%s\".\n"
> "Please check that RTE_MACHINE is set correctly.\n",
> --
> 1.8.5.3
>
>
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