diff options
Diffstat (limited to 'arch/x86/kernel/ds.c')
| -rw-r--r-- | arch/x86/kernel/ds.c | 464 |
1 files changed, 464 insertions, 0 deletions
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c new file mode 100644 index 000000000000..1c5ca4d18787 --- /dev/null +++ b/arch/x86/kernel/ds.c @@ -0,0 +1,464 @@ +/* + * Debug Store support + * + * This provides a low-level interface to the hardware's Debug Store + * feature that is used for last branch recording (LBR) and + * precise-event based sampling (PEBS). + * + * Different architectures use a different DS layout/pointer size. + * The below functions therefore work on a void*. + * + * + * Since there is no user for PEBS, yet, only LBR (or branch + * trace store, BTS) is supported. + * + * + * Copyright (C) 2007 Intel Corporation. + * Markus Metzger <markus.t.metzger@intel.com>, Dec 2007 + */ + +#include <asm/ds.h> + +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/slab.h> + + +/* + * Debug Store (DS) save area configuration (see Intel64 and IA32 + * Architectures Software Developer's Manual, section 18.5) + * + * The DS configuration consists of the following fields; different + * architetures vary in the size of those fields. + * - double-word aligned base linear address of the BTS buffer + * - write pointer into the BTS buffer + * - end linear address of the BTS buffer (one byte beyond the end of + * the buffer) + * - interrupt pointer into BTS buffer + * (interrupt occurs when write pointer passes interrupt pointer) + * - double-word aligned base linear address of the PEBS buffer + * - write pointer into the PEBS buffer + * - end linear address of the PEBS buffer (one byte beyond the end of + * the buffer) + * - interrupt pointer into PEBS buffer + * (interrupt occurs when write pointer passes interrupt pointer) + * - value to which counter is reset following counter overflow + * + * On later architectures, the last branch recording hardware uses + * 64bit pointers even in 32bit mode. + * + * + * Branch Trace Store (BTS) records store information about control + * flow changes. They at least provide the following information: + * - source linear address + * - destination linear address + * + * Netburst supported a predicated bit that had been dropped in later + * architectures. We do not suppor it. + * + * + * In order to abstract from the actual DS and BTS layout, we describe + * the access to the relevant fields. + * Thanks to Andi Kleen for proposing this design. + * + * The implementation, however, is not as general as it might seem. In + * order to stay somewhat simple and efficient, we assume an + * underlying unsigned type (mostly a pointer type) and we expect the + * field to be at least as big as that type. + */ + +/* + * A special from_ip address to indicate that the BTS record is an + * info record that needs to be interpreted or skipped. + */ +#define BTS_ESCAPE_ADDRESS (-1) + +/* + * A field access descriptor + */ +struct access_desc { + unsigned char offset; + unsigned char size; +}; + +/* + * The configuration for a particular DS/BTS hardware implementation. + */ +struct ds_configuration { + /* the DS configuration */ + unsigned char sizeof_ds; + struct access_desc bts_buffer_base; + struct access_desc bts_index; + struct access_desc bts_absolute_maximum; + struct access_desc bts_interrupt_threshold; + /* the BTS configuration */ + unsigned char sizeof_bts; + struct access_desc from_ip; + struct access_desc to_ip; + /* BTS variants used to store additional information like + timestamps */ + struct access_desc info_type; + struct access_desc info_data; + unsigned long debugctl_mask; +}; + +/* + * The global configuration used by the below accessor functions + */ +static struct ds_configuration ds_cfg; + +/* + * Accessor functions for some DS and BTS fields using the above + * global ptrace_bts_cfg. + */ +static inline unsigned long get_bts_buffer_base(char *base) +{ + return *(unsigned long *)(base + ds_cfg.bts_buffer_base.offset); +} +static inline void set_bts_buffer_base(char *base, unsigned long value) +{ + (*(unsigned long *)(base + ds_cfg.bts_buffer_base.offset)) = value; +} +static inline unsigned long get_bts_index(char *base) +{ + return *(unsigned long *)(base + ds_cfg.bts_index.offset); +} +static inline void set_bts_index(char *base, unsigned long value) +{ + (*(unsigned long *)(base + ds_cfg.bts_index.offset)) = value; +} +static inline unsigned long get_bts_absolute_maximum(char *base) +{ + return *(unsigned long *)(base + ds_cfg.bts_absolute_maximum.offset); +} +static inline void set_bts_absolute_maximum(char *base, unsigned long value) +{ + (*(unsigned long *)(base + ds_cfg.bts_absolute_maximum.offset)) = value; +} +static inline unsigned long get_bts_interrupt_threshold(char *base) +{ + return *(unsigned long *)(base + ds_cfg.bts_interrupt_threshold.offset); +} +static inline void set_bts_interrupt_threshold(char *base, unsigned long value) +{ + (*(unsigned long *)(base + ds_cfg.bts_interrupt_threshold.offset)) = value; +} +static inline unsigned long get_from_ip(char *base) +{ + return *(unsigned long *)(base + ds_cfg.from_ip.offset); +} +static inline void set_from_ip(char *base, unsigned long value) +{ + (*(unsigned long *)(base + ds_cfg.from_ip.offset)) = value; +} +static inline unsigned long get_to_ip(char *base) +{ + return *(unsigned long *)(base + ds_cfg.to_ip.offset); +} +static inline void set_to_ip(char *base, unsigned long value) +{ + (*(unsigned long *)(base + ds_cfg.to_ip.offset)) = value; +} +static inline unsigned char get_info_type(char *base) +{ + return *(unsigned char *)(base + ds_cfg.info_type.offset); +} +static inline void set_info_type(char *base, unsigned char value) +{ + (*(unsigned char *)(base + ds_cfg.info_type.offset)) = value; +} +static inline unsigned long get_info_data(char *base) +{ + return *(unsigned long *)(base + ds_cfg.info_data.offset); +} +static inline void set_info_data(char *base, unsigned long value) +{ + (*(unsigned long *)(base + ds_cfg.info_data.offset)) = value; +} + + +int ds_allocate(void **dsp, size_t bts_size_in_bytes) +{ + size_t bts_size_in_records; + unsigned long bts; + void *ds; + + if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts) + return -EOPNOTSUPP; + + if (bts_size_in_bytes < 0) + return -EINVAL; + + bts_size_in_records = + bts_size_in_bytes / ds_cfg.sizeof_bts; + bts_size_in_bytes = + bts_size_in_records * ds_cfg.sizeof_bts; + + if (bts_size_in_bytes <= 0) + return -EINVAL; + + bts = (unsigned long)kzalloc(bts_size_in_bytes, GFP_KERNEL); + + if (!bts) + return -ENOMEM; + + ds = kzalloc(ds_cfg.sizeof_ds, GFP_KERNEL); + + if (!ds) { + kfree((void *)bts); + return -ENOMEM; + } + + set_bts_buffer_base(ds, bts); + set_bts_index(ds, bts); + set_bts_absolute_maximum(ds, bts + bts_size_in_bytes); + set_bts_interrupt_threshold(ds, bts + bts_size_in_bytes + 1); + + *dsp = ds; + return 0; +} + +int ds_free(void **dsp) +{ + if (*dsp) + kfree((void *)get_bts_buffer_base(*dsp)); + kfree(*dsp); + *dsp = 0; + + return 0; +} + +int ds_get_bts_size(void *ds) +{ + int size_in_bytes; + + if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts) + return -EOPNOTSUPP; + + if (!ds) + return 0; + + size_in_bytes = + get_bts_absolute_maximum(ds) - + get_bts_buffer_base(ds); + return size_in_bytes; +} + +int ds_get_bts_end(void *ds) +{ + int size_in_bytes = ds_get_bts_size(ds); + + if (size_in_bytes <= 0) + return size_in_bytes; + + return size_in_bytes / ds_cfg.sizeof_bts; +} + +int ds_get_bts_index(void *ds) +{ + int index_offset_in_bytes; + + if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts) + return -EOPNOTSUPP; + + index_offset_in_bytes = + get_bts_index(ds) - + get_bts_buffer_base(ds); + + return index_offset_in_bytes / ds_cfg.sizeof_bts; +} + +int ds_set_overflow(void *ds, int method) +{ + switch (method) { + case DS_O_SIGNAL: + return -EOPNOTSUPP; + case DS_O_WRAP: + return 0; + default: + return -EINVAL; + } +} + +int ds_get_overflow(void *ds) +{ + return DS_O_WRAP; +} + +int ds_clear(void *ds) +{ + int bts_size = ds_get_bts_size(ds); + unsigned long bts_base; + + if (bts_size <= 0) + return bts_size; + + bts_base = get_bts_buffer_base(ds); + memset((void *)bts_base, 0, bts_size); + + set_bts_index(ds, bts_base); + return 0; +} + +int ds_read_bts(void *ds, int index, struct bts_struct *out) +{ + void *bts; + + if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts) + return -EOPNOTSUPP; + + if (index < 0) + return -EINVAL; + + if (index >= ds_get_bts_size(ds)) + return -EINVAL; + + bts = (void *)(get_bts_buffer_base(ds) + (index * ds_cfg.sizeof_bts)); + + memset(out, 0, sizeof(*out)); + if (get_from_ip(bts) == BTS_ESCAPE_ADDRESS) { + out->qualifier = get_info_type(bts); + out->variant.jiffies = get_info_data(bts); + } else { + out->qualifier = BTS_BRANCH; + out->variant.lbr.from_ip = get_from_ip(bts); + out->variant.lbr.to_ip = get_to_ip(bts); + } + + return sizeof(*out);; +} + +int ds_write_bts(void *ds, const struct bts_struct *in) +{ + unsigned long bts; + + if (!ds_cfg.sizeof_ds || !ds_cfg.sizeof_bts) + return -EOPNOTSUPP; + + if (ds_get_bts_size(ds) <= 0) + return -ENXIO; + + bts = get_bts_index(ds); + + memset((void *)bts, 0, ds_cfg.sizeof_bts); + switch (in->qualifier) { + case BTS_INVALID: + break; + + case BTS_BRANCH: + set_from_ip((void *)bts, in->variant.lbr.from_ip); + set_to_ip((void *)bts, in->variant.lbr.to_ip); + break; + + case BTS_TASK_ARRIVES: + case BTS_TASK_DEPARTS: + set_from_ip((void *)bts, BTS_ESCAPE_ADDRESS); + set_info_type((void *)bts, in->qualifier); + set_info_data((void *)bts, in->variant.jiffies); + break; + + default: + return -EINVAL; + } + + bts = bts + ds_cfg.sizeof_bts; + if (bts >= get_bts_absolute_maximum(ds)) + bts = get_bts_buffer_base(ds); + set_bts_index(ds, bts); + + return ds_cfg.sizeof_bts; +} + +unsigned long ds_debugctl_mask(void) +{ + return ds_cfg.debugctl_mask; +} + +#ifdef __i386__ +static const struct ds_configuration ds_cfg_netburst = { + .sizeof_ds = 9 * 4, + .bts_buffer_base = { 0, 4 }, + .bts_index = { 4, 4 }, + .bts_absolute_maximum = { 8, 4 }, + .bts_interrupt_threshold = { 12, 4 }, + .sizeof_bts = 3 * 4, + .from_ip = { 0, 4 }, + .to_ip = { 4, 4 }, + .info_type = { 4, 1 }, + .info_data = { 8, 4 }, + .debugctl_mask = (1<<2)|(1<<3) +}; + +static const struct ds_configuration ds_cfg_pentium_m = { + .sizeof_ds = 9 * 4, + .bts_buffer_base = { 0, 4 }, + .bts_index = { 4, 4 }, + .bts_absolute_maximum = { 8, 4 }, + .bts_interrupt_threshold = { 12, 4 }, + .sizeof_bts = 3 * 4, + .from_ip = { 0, 4 }, + .to_ip = { 4, 4 }, + .info_type = { 4, 1 }, + .info_data = { 8, 4 }, + .debugctl_mask = (1<<6)|(1<<7) +}; +#endif /* _i386_ */ + +static const struct ds_configuration ds_cfg_core2 = { + .sizeof_ds = 9 * 8, + .bts_buffer_base = { 0, 8 }, + .bts_index = { 8, 8 }, + .bts_absolute_maximum = { 16, 8 }, + .bts_interrupt_threshold = { 24, 8 }, + .sizeof_bts = 3 * 8, + .from_ip = { 0, 8 }, + .to_ip = { 8, 8 }, + .info_type = { 8, 1 }, + .info_data = { 16, 8 }, + .debugctl_mask = (1<<6)|(1<<7)|(1<<9) +}; + +static inline void +ds_configure(const struct ds_configuration *cfg) +{ + ds_cfg = *cfg; +} + +void __cpuinit ds_init_intel(struct cpuinfo_x86 *c) +{ + switch (c->x86) { + case 0x6: + switch (c->x86_model) { +#ifdef __i386__ + case 0xD: + case 0xE: /* Pentium M */ + ds_configure(&ds_cfg_pentium_m); + break; +#endif /* _i386_ */ + case 0xF: /* Core2 */ + ds_configure(&ds_cfg_core2); + break; + default: + /* sorry, don't know about them */ + break; + } + break; + case 0xF: + switch (c->x86_model) { +#ifdef __i386__ + case 0x0: + case 0x1: + case 0x2: /* Netburst */ + ds_configure(&ds_cfg_netburst); + break; +#endif /* _i386_ */ + default: + /* sorry, don't know about them */ + break; + } + break; + default: + /* sorry, don't know about them */ + break; + } +} |