diff options
| -rw-r--r-- | manual/dynlink.texi | 85 | ||||
| -rw-r--r-- | sysdeps/x86/dl-diagnostics-cpu.c | 384 |
2 files changed, 468 insertions, 1 deletions
diff --git a/manual/dynlink.texi b/manual/dynlink.texi index 06a6c15533..f2f2341818 100644 --- a/manual/dynlink.texi +++ b/manual/dynlink.texi @@ -228,7 +228,90 @@ reported by the @code{uname} function. @xref{Platform Type}. @item x86.cpu_features.@dots{} These items are specific to the i386 and x86-64 architectures. They reflect supported CPU features and information on cache geometry, mostly -collected using the @code{CPUID} instruction. +collected using the CPUID instruction. + +@item x86.processor[@var{index}].@dots{} +These are additional items for the i386 and x86-64 architectures, as +described below. They mostly contain raw data from the CPUID +instruction. The probes are performed for each active CPU for the +@code{ld.so} process, and data for different probed CPUs receives a +uniqe @var{index} value. Some CPUID data is expected to differ from CPU +core to CPU core. In some cases, CPUs are not correctly initialized and +indicate the presence of different feature sets. + +@item x86.processor[@var{index}].requested=@var{kernel-cpu} +The kernel is told to run the subsequent probing on the CPU numbered +@var{kernel-cpu}. The values @var{kernel-cpu} and @var{index} can be +distinct if there are gaps in the process CPU affinity mask. This line +is not included if CPU affinity mask information is not available. + +@item x86.processor[@var{index}].observed=@var{kernel-cpu} +This line reports the kernel CPU number @var{kernel-cpu} on which the +probing code initially ran. If the CPU number cannot be obtained, +this line is not printed. + +@item x86.processor[@var{index}].observed_node=@var{node} +This reports the observed NUMA node number, as reported by the +@code{getcpu} system call. If this information cannot be obtained, this +line is not printed. + +@item x86.processor[@var{index}].cpuid_leaves=@var{count} +This line indicates that @var{count} distinct CPUID leaves were +encountered. (This reflects internal @code{ld.so} storage space, it +does not directly correspond to @code{CPUID} enumeration ranges.) + +@item x86.processor[@var{index}].ecx_limit=@var{value} +The CPUID data extraction code uses a brute-force approach to enumerate +subleaves (see the @samp{.subleaf_eax} lines below). The last +@code{%rcx} value used in a CPUID query on this probed CPU was +@var{value}. + +@item x86.processor[@var{index}].cpuid.eax[@var{query_eax}].eax=@var{eax} +@itemx x86.processor[@var{index}].cpuid.eax[@var{query_eax}].ebx=@var{ebx} +@itemx x86.processor[@var{index}].cpuid.eax[@var{query_eax}].ecx=@var{ecx} +@itemx x86.processor[@var{index}].cpuid.eax[@var{query_eax}].edx=@var{edx} +These lines report the register contents after executing the CPUID +instruction with @samp{%rax == @var{query_eax}} and @samp{%rcx == 0} (a +@dfn{leaf}). For the first probed CPU (with a zero @var{index}), only +leaves with non-zero register contents are reported. For subsequent +CPUs, only leaves whose register contents differs from the previously +probed CPUs (with @var{index} one less) are reported. + +Basic and extended leaves are reported using the same syntax. This +means there is a large jump in @var{query_eax} for the first reported +extended leaf. + +@item x86.processor[@var{index}].cpuid.subleaf_eax[@var{query_eax}].ecx[@var{query_ecx}].eax=@var{eax} +@itemx x86.processor[@var{index}].cpuid.subleaf_eax[@var{query_eax}].ecx[@var{query_ecx}].ebx=@var{ebx} +@itemx x86.processor[@var{index}].cpuid.subleaf_eax[@var{query_eax}].ecx[@var{query_ecx}].ecx=@var{ecx} +@itemx x86.processor[@var{index}].cpuid.subleaf_eax[@var{query_eax}].ecx[@var{query_ecx}].edx=@var{edx} +This is similar to the leaves above, but for a @dfn{subleaf}. For +subleaves, the CPUID instruction is executed with @samp{%rax == +@var{query_eax}} and @samp{%rcx == @var{query_ecx}}, so the result +depends on both register values. The same rules about filtering zero +and identical results apply. + +@item x86.processor[@var{index}].cpuid.subleaf_eax[@var{query_eax}].ecx[@var{query_ecx}].until_ecx=@var{ecx_limit} +Some CPUID results are the same regardless the @var{query_ecx} value. +If this situation is detected, a line with the @samp{.until_ecx} +selector ins included, and this indicates that the CPUID register +contents is the same for @code{%rcx} values between @var{query_ecx} +and @var{ecx_limit} (inclusive). + +@item x86.processor[@var{index}].cpuid.subleaf_eax[@var{query_eax}].ecx[@var{query_ecx}].ecx_query_mask=0xff +This line indicates that in an @samp{.until_ecx} range, the CPUID +instruction preserved the lowested 8 bits of the input @code{%rcx} in +the output @code{%rcx} registers. Otherwise, the subleaves in the range +have identical values. This special treatment is necessary to report +compact range information in case such copying occurs (because the +subleaves would otherwise be all different). + +@item x86.processor[@var{index}].xgetbv.ecx[@var{query_ecx}]=@var{result} +This line shows the 64-bit @var{result} value in the @code{%rdx:%rax} +register pair after executing the XGETBV instruction with @code{%rcx} +set to @var{query_ecx}. Zero values and values matching the previously +probed CPU are omitted. Nothing is printed if the system does not +support the XGETBV instruction. @end table @node Dynamic Linker Introspection diff --git a/sysdeps/x86/dl-diagnostics-cpu.c b/sysdeps/x86/dl-diagnostics-cpu.c index c76ea3be16..ceafde9481 100644 --- a/sysdeps/x86/dl-diagnostics-cpu.c +++ b/sysdeps/x86/dl-diagnostics-cpu.c @@ -17,7 +17,18 @@ <https://www.gnu.org/licenses/>. */ #include <dl-diagnostics.h> + +#include <array_length.h> +#include <cpu-features.h> +#include <cpuid.h> +#include <dl-iterate_cpu.h> #include <ldsodefs.h> +#include <stdbool.h> +#include <string.h> +#include <sysdep.h> + +/* The generic CPUID dumping code. */ +static void _dl_diagnostics_cpuid (void); static void print_cpu_features_value (const char *label, uint64_t value) @@ -120,4 +131,377 @@ _dl_diagnostics_cpu (void) + sizeof (cpu_features->cachesize_non_temporal_divisor) == sizeof (*cpu_features), "last cpu_features field has been printed"); + + _dl_diagnostics_cpuid (); +} + +/* The following code implements a generic CPUID dumper that tries to + gather CPUID data without knowing about CPUID implementation + details. */ + +/* Register arguments to CPUID. Multiple ECX subleaf values yielding + the same result are combined, to shorten the output. Both + identical matches (EAX to EDX are the same) and matches where EAX, + EBX, EDX, and ECX are equal except in the lower byte, which must + match the query ECX value. The latter is needed to compress ranges + on CPUs which preserve the lowest byte in ECX if an unknown leaf is + queried. */ +struct cpuid_query +{ + unsigned int eax; + unsigned ecx_first; + unsigned ecx_last; + bool ecx_preserves_query_byte; +}; + +/* Single integer value that can be used for sorting/ordering + comparisons. Uses Q->eax and Q->ecx_first only because ecx_last is + always greater than the previous ecx_first value and less than the + subsequent one. */ +static inline unsigned long long int +cpuid_query_combined (struct cpuid_query *q) +{ + /* ecx can be -1 (that is, ~0U). If this happens, this the only ecx + value for this eax value, so the ordering does not matter. */ + return ((unsigned long long int) q->eax << 32) | (unsigned int) q->ecx_first; +}; + +/* Used for differential reporting of zero/non-zero values. */ +static const struct cpuid_registers cpuid_registers_zero; + +/* Register arguments to CPUID paired with the results that came back. */ +struct cpuid_query_result +{ + struct cpuid_query q; + struct cpuid_registers r; +}; + +/* During a first enumeration pass, we try to collect data for + cpuid_initial_subleaf_limit subleaves per leaf/EAX value. If we run + out of space, we try once more with applying the lower limit. */ +enum { cpuid_main_leaf_limit = 128 }; +enum { cpuid_initial_subleaf_limit = 512 }; +enum { cpuid_subleaf_limit = 32 }; + +/* Offset of the extended leaf area. */ +enum {cpuid_extended_leaf_offset = 0x80000000 }; + +/* Collected CPUID data. Everything is stored in a statically sized + array that is sized so that the second pass will collect some data + for all leaves, after the limit is applied. On the second pass, + ecx_limit is set to cpuid_subleaf_limit. */ +struct cpuid_collected_data +{ + unsigned int used; + unsigned int ecx_limit; + uint64_t xgetbv_ecx_0; + struct cpuid_query_result qr[cpuid_main_leaf_limit + * 2 * cpuid_subleaf_limit]; +}; + +/* Fill in the result of a CPUID query. Returns true if there is + room, false if nothing could be stored. */ +static bool +_dl_diagnostics_cpuid_store (struct cpuid_collected_data *ccd, + unsigned eax, int ecx) +{ + if (ccd->used >= array_length (ccd->qr)) + return false; + + /* Tentatively fill in the next value. */ + __cpuid_count (eax, ecx, + ccd->qr[ccd->used].r.eax, + ccd->qr[ccd->used].r.ebx, + ccd->qr[ccd->used].r.ecx, + ccd->qr[ccd->used].r.edx); + + /* If the ECX subleaf is next subleaf after the previous one (for + the same leaf), and the values are the same, merge the result + with the already-stored one. Do this before skipping zero + leaves, which avoids artifiacts for ECX == 256 queries. */ + if (ccd->used > 0 + && ccd->qr[ccd->used - 1].q.eax == eax + && ccd->qr[ccd->used - 1].q.ecx_last + 1 == ecx) + { + /* Exact match of the previous result. Ignore the value of + ecx_preserves_query_byte if this is a singleton range so far + because we can treat ECX as fixed if the same value repeats. */ + if ((!ccd->qr[ccd->used - 1].q.ecx_preserves_query_byte + || (ccd->qr[ccd->used - 1].q.ecx_first + == ccd->qr[ccd->used - 1].q.ecx_last)) + && memcmp (&ccd->qr[ccd->used - 1].r, &ccd->qr[ccd->used].r, + sizeof (ccd->qr[ccd->used].r)) == 0) + { + ccd->qr[ccd->used - 1].q.ecx_last = ecx; + /* ECX is now fixed because the same value has been observed + twice, even if we had a low-byte match before. */ + ccd->qr[ccd->used - 1].q.ecx_preserves_query_byte = false; + return true; + } + /* Match except for the low byte in ECX, which must match the + incoming ECX value. */ + if (ccd->qr[ccd->used - 1].q.ecx_preserves_query_byte + && (ecx & 0xff) == (ccd->qr[ccd->used].r.ecx & 0xff) + && ccd->qr[ccd->used].r.eax == ccd->qr[ccd->used - 1].r.eax + && ccd->qr[ccd->used].r.ebx == ccd->qr[ccd->used - 1].r.ebx + && ((ccd->qr[ccd->used].r.ecx & 0xffffff00) + == (ccd->qr[ccd->used - 1].r.ecx & 0xffffff00)) + && ccd->qr[ccd->used].r.edx == ccd->qr[ccd->used - 1].r.edx) + { + ccd->qr[ccd->used - 1].q.ecx_last = ecx; + return true; + } + } + + /* Do not store zero results. All-zero values usually mean that the + subleaf is unsupported. */ + if (ccd->qr[ccd->used].r.eax == 0 + && ccd->qr[ccd->used].r.ebx == 0 + && ccd->qr[ccd->used].r.ecx == 0 + && ccd->qr[ccd->used].r.edx == 0) + return true; + + /* The result needs to be stored. Fill in the query parameters and + consume the storage. */ + ccd->qr[ccd->used].q.eax = eax; + ccd->qr[ccd->used].q.ecx_first = ecx; + ccd->qr[ccd->used].q.ecx_last = ecx; + ccd->qr[ccd->used].q.ecx_preserves_query_byte + = (ecx & 0xff) == (ccd->qr[ccd->used].r.ecx & 0xff); + ++ccd->used; + return true; +} + +/* Collected CPUID data into *CCD. If LIMIT, apply per-leaf limits to + avoid exceeding the pre-allocated space. Return true if all data + could be stored, false if the retrying without a limit is + requested. */ +static bool +_dl_diagnostics_cpuid_collect_1 (struct cpuid_collected_data *ccd, bool limit) +{ + ccd->used = 0; + ccd->ecx_limit + = (limit ? cpuid_subleaf_limit : cpuid_initial_subleaf_limit) - 1; + _dl_diagnostics_cpuid_store (ccd, 0x00, 0x00); + if (ccd->used == 0) + /* CPUID reported all 0. Should not happen. */ + return true; + unsigned int maximum_leaf = ccd->qr[0x00].r.eax; + if (limit && maximum_leaf >= cpuid_main_leaf_limit) + maximum_leaf = cpuid_main_leaf_limit - 1; + + for (unsigned int eax = 1; eax <= maximum_leaf; ++eax) + { + for (unsigned int ecx = 0; ecx <= ccd->ecx_limit; ++ecx) + if (!_dl_diagnostics_cpuid_store (ccd, eax, ecx)) + return false; + } + + if (!_dl_diagnostics_cpuid_store (ccd, cpuid_extended_leaf_offset, 0x00)) + return false; + maximum_leaf = ccd->qr[ccd->used - 1].r.eax; + if (maximum_leaf < cpuid_extended_leaf_offset) + /* No extended CPUID information. */ + return true; + if (limit + && maximum_leaf - cpuid_extended_leaf_offset >= cpuid_main_leaf_limit) + maximum_leaf = cpuid_extended_leaf_offset + cpuid_main_leaf_limit - 1; + for (unsigned int eax = cpuid_extended_leaf_offset + 1; + eax <= maximum_leaf; ++eax) + { + for (unsigned int ecx = 0; ecx <= ccd->ecx_limit; ++ecx) + if (!_dl_diagnostics_cpuid_store (ccd, eax, ecx)) + return false; + } + return true; +} + +/* Call _dl_diagnostics_cpuid_collect_1 twice if necessary, the + second time with the limit applied. */ +static void +_dl_diagnostics_cpuid_collect (struct cpuid_collected_data *ccd) +{ + if (!_dl_diagnostics_cpuid_collect_1 (ccd, false)) + _dl_diagnostics_cpuid_collect_1 (ccd, true); + + /* Re-use the result of the official feature probing here. */ + const struct cpu_features *cpu_features = __get_cpu_features (); + if (CPU_FEATURES_CPU_P (cpu_features, OSXSAVE)) + { + unsigned int xcrlow; + unsigned int xcrhigh; + asm ("xgetbv" : "=a" (xcrlow), "=d" (xcrhigh) : "c" (0)); + ccd->xgetbv_ecx_0 = ((uint64_t) xcrhigh << 32) + xcrlow; + } + else + ccd->xgetbv_ecx_0 = 0; +} + +/* Print a CPUID register value (passed as REG_VALUE) if it differs + from the expected REG_REFERENCE value. PROCESSOR_INDEX is the + process sequence number (always starting at zero; not a kernel ID). */ +static void +_dl_diagnostics_cpuid_print_reg (unsigned int processor_index, + const struct cpuid_query *q, + const char *reg_label, unsigned int reg_value, + bool subleaf) +{ + if (subleaf) + _dl_printf ("x86.processor[0x%x].cpuid.subleaf_eax[0x%x]" + ".ecx[0x%x].%s=0x%x\n", + processor_index, q->eax, q->ecx_first, reg_label, reg_value); + else + _dl_printf ("x86.processor[0x%x].cpuid.eax[0x%x].%s=0x%x\n", + processor_index, q->eax, reg_label, reg_value); +} + +/* Print CPUID result values in *RESULT for the query in + CCD->qr[CCD_IDX]. PROCESSOR_INDEX is the process sequence number + (always starting at zero; not a kernel ID). */ +static void +_dl_diagnostics_cpuid_print_query (unsigned int processor_index, + struct cpuid_collected_data *ccd, + unsigned int ccd_idx, + const struct cpuid_registers *result) +{ + /* Treat this as a value if subleaves if ecx isn't zero (maybe + within the [ecx_fist, ecx_last] range), or if eax matches its + neighbors. If the range is [0, ecx_limit], then the subleaves + are not distinct (independently of ecx_preserves_query_byte), + so do not report them separately. */ + struct cpuid_query *q = &ccd->qr[ccd_idx].q; + bool subleaf = (q->ecx_first > 0 + || (q->ecx_first != q->ecx_last + && !(q->ecx_first == 0 && q->ecx_last == ccd->ecx_limit)) + || (ccd_idx > 0 && q->eax == ccd->qr[ccd_idx - 1].q.eax) + || (ccd_idx + 1 < ccd->used + && q->eax == ccd->qr[ccd_idx + 1].q.eax)); + _dl_diagnostics_cpuid_print_reg (processor_index, q, "eax", result->eax, + subleaf); + _dl_diagnostics_cpuid_print_reg (processor_index, q, "ebx", result->ebx, + subleaf); + _dl_diagnostics_cpuid_print_reg (processor_index, q, "ecx", result->ecx, + subleaf); + _dl_diagnostics_cpuid_print_reg (processor_index, q, "edx", result->edx, + subleaf); + + if (subleaf && q->ecx_first != q->ecx_last) + { + _dl_printf ("x86.processor[0x%x].cpuid.subleaf_eax[0x%x]" + ".ecx[0x%x].until_ecx=0x%x\n", + processor_index, q->eax, q->ecx_first, q->ecx_last); + if (q->ecx_preserves_query_byte) + _dl_printf ("x86.processor[0x%x].cpuid.subleaf_eax[0x%x]" + ".ecx[0x%x].ecx_query_mask=0xff\n", + processor_index, q->eax, q->ecx_first); + } +} + +/* Perform differential reporting of the data in *CURRENT against + *BASE. REQUESTED_CPU is the kernel CPU ID the thread was + configured to run on, or -1 if no configuration was possible. + PROCESSOR_INDEX is the process sequence number (always starting at + zero; not a kernel ID). */ +static void +_dl_diagnostics_cpuid_report (struct dl_iterate_cpu *dci, + struct cpuid_collected_data *current, + struct cpuid_collected_data *base) +{ + if (dci->requested_cpu >= 0) + _dl_printf ("x86.processor[0x%x].requested=0x%x\n", + dci->processor_index, dci->requested_cpu); + if (dci->actual_cpu >= 0) + _dl_printf ("x86.processor[0x%x].observed=0x%x\n", + dci->processor_index, dci->actual_cpu); + if (dci->actual_node >= 0) + _dl_printf ("x86.processor[0x%x].observed_node=0x%x\n", + dci->processor_index, dci->actual_node); + + _dl_printf ("x86.processor[0x%x].cpuid_leaves=0x%x\n", + dci->processor_index, current->used); + _dl_printf ("x86.processor[0x%x].ecx_limit=0x%x\n", + dci->processor_index, current->ecx_limit); + + unsigned int base_idx = 0; + for (unsigned int current_idx = 0; current_idx < current->used; + ++current_idx) + { + /* Report missing data on the current CPU as 0. */ + unsigned long long int current_query + = cpuid_query_combined (¤t->qr[current_idx].q); + while (base_idx < base->used + && cpuid_query_combined (&base->qr[base_idx].q) < current_query) + { + _dl_diagnostics_cpuid_print_query (dci->processor_index, + base, base_idx, + &cpuid_registers_zero); + ++base_idx; + } + + if (base_idx < base->used + && cpuid_query_combined (&base->qr[base_idx].q) == current_query) + { + _Static_assert (sizeof (struct cpuid_registers) == 4 * 4, + "no padding in struct cpuid_registers"); + if (current->qr[current_idx].q.ecx_last + != base->qr[base_idx].q.ecx_last + || memcmp (¤t->qr[current_idx].r, + &base->qr[base_idx].r, + sizeof (struct cpuid_registers)) != 0) + /* The ECX range or the values have changed. Show the + new values. */ + _dl_diagnostics_cpuid_print_query (dci->processor_index, + current, current_idx, + ¤t->qr[current_idx].r); + ++base_idx; + } + else + /* Data is absent in the base reference. Report the new data. */ + _dl_diagnostics_cpuid_print_query (dci->processor_index, + current, current_idx, + ¤t->qr[current_idx].r); + } + + if (current->xgetbv_ecx_0 != base->xgetbv_ecx_0) + { + /* Re-use the 64-bit printing routine. */ + _dl_printf ("x86.processor[0x%x].", dci->processor_index); + _dl_diagnostics_print_labeled_value ("xgetbv.ecx[0x0]", + current->xgetbv_ecx_0); + } +} + +static void +_dl_diagnostics_cpuid (void) +{ +#if !HAS_CPUID + /* CPUID is not supported, so there is nothing to dump. */ + if (__get_cpuid_max (0, 0) == 0) + return; +#endif + + struct dl_iterate_cpu dic; + _dl_iterate_cpu_init (&dic); + + /* Two copies of the data are used. Data is written to the index + (dic.processor_index & 1). The previous version against which the + data dump is reported is at index !(processor_index & 1). */ + struct cpuid_collected_data ccd[2]; + + /* The initial data is presumed to be all zero. Zero results are + not recorded. */ + ccd[1].used = 0; + ccd[1].xgetbv_ecx_0 = 0; + + /* Run the CPUID probing on a specific CPU. There are expected + differences for encoding core IDs and topology information in + CPUID output, but some firmware/kernel bugs also may result in + asymmetric data across CPUs in some cases. */ + while (_dl_iterate_cpu_next (&dic)) + { + _dl_diagnostics_cpuid_collect (&ccd[dic.processor_index & 1]); + _dl_diagnostics_cpuid_report + (&dic, &ccd[dic.processor_index & 1], + &ccd[!(dic.processor_index & 1)]); + } } |