mirror of
https://github.com/tobast/libunwind-eh_elf.git
synced 2024-11-22 07:37:38 +01:00
Integrate fast trace into backtrace().
This commit is contained in:
Lassi Tuura
Arun Sharma
parent
9e98f15e9a
commit
44a14d1364
11 changed files with 225 additions and 95 deletions
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@ -297,8 +297,6 @@ unw_tdep_frame_t;
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#define unw_tdep_is_fpreg UNW_ARCH_OBJ(is_fpreg)
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extern int unw_tdep_is_fpreg (int);
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#define unw_tdep_make_frame_cache(n) (0)
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#define unw_tdep_free_frame_cache(p) do {} while(0)
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#define unw_tdep_trace(cur,addr,n,c) (-UNW_ENOINFO)
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#if defined(__cplusplus) || defined(c_plusplus)
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@ -228,6 +228,7 @@ unw_save_loc_t;
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#define unw_regname UNW_ARCH_OBJ(regname)
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#define unw_flush_cache UNW_ARCH_OBJ(flush_cache)
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#define unw_strerror UNW_ARCH_OBJ(strerror)
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#define unw_backtrace UNW_OBJ(backtrace)
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extern unw_addr_space_t unw_create_addr_space (unw_accessors_t *, int);
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extern void unw_destroy_addr_space (unw_addr_space_t);
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@ -253,4 +254,6 @@ extern int unw_handle_signal_frame (unw_cursor_t *);
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extern int unw_get_proc_name (unw_cursor_t *, char *, size_t, unw_word_t *);
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extern const char *unw_strerror (int);
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extern int unw_backtrace (void **buffer, int size);
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extern unw_addr_space_t unw_local_addr_space;
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@ -124,8 +124,6 @@ unw_tdep_proc_info_t;
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#define unw_tdep_getcontext UNW_ARCH_OBJ (getcontext)
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extern int unw_tdep_getcontext (unw_tdep_context_t *);
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#define unw_tdep_make_frame_cache(n) (0)
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#define unw_tdep_free_frame_cache(p) do {} while(0)
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#define unw_tdep_trace(cur,addr,n,c) (-UNW_ENOINFO)
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#if defined(__cplusplus) || defined(c_plusplus)
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@ -193,8 +193,6 @@ extern unw_word_t _Uia64_find_dyn_list (unw_addr_space_t, unw_dyn_info_t *,
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signal-safe. */
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extern int _Uia64_get_kernel_table (unw_dyn_info_t *);
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#define unw_tdep_make_frame_cache(n) (0)
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#define unw_tdep_free_frame_cache(p) do {} while(0)
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#define unw_tdep_trace(cur,addr,n,c) (-UNW_ENOINFO)
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#if defined(__cplusplus) || defined(c_plusplus)
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@ -154,8 +154,6 @@ extern int unw_tdep_getcontext (ucontext_t *uc);
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#define unw_tdep_is_fpreg UNW_ARCH_OBJ(is_fpreg)
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extern int unw_tdep_is_fpreg (int);
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#define unw_tdep_make_frame_cache(n) (0)
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#define unw_tdep_free_frame_cache(p) do {} while(0)
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#define unw_tdep_trace(cur,addr,n,c) (-UNW_ENOINFO)
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#if defined(__cplusplus) || defined(c_plusplus)
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@ -206,8 +206,6 @@ unw_tdep_frame_t;
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#define unw_tdep_is_fpreg UNW_ARCH_OBJ(is_fpreg)
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extern int unw_tdep_is_fpreg (int);
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#define unw_tdep_make_frame_cache(n) (0)
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#define unw_tdep_free_frame_cache(p) do {} while(0)
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#define unw_tdep_trace(cur,addr,n,c) (-UNW_ENOINFO)
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#if defined(__cplusplus) || defined(c_plusplus)
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@ -263,8 +263,6 @@ unw_tdep_frame_t;
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#define unw_tdep_is_fpreg UNW_ARCH_OBJ(is_fpreg)
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extern int unw_tdep_is_fpreg (int);
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#define unw_tdep_make_frame_cache(n) (0)
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#define unw_tdep_free_frame_cache(p) do {} while(0)
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#define unw_tdep_trace(cur,addr,n,c) (-UNW_ENOINFO)
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#if defined(__cplusplus) || defined(c_plusplus)
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@ -186,8 +186,6 @@ extern int unw_tdep_getcontext (unw_tdep_context_t *);
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#define unw_tdep_is_fpreg UNW_ARCH_OBJ(is_fpreg)
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extern int unw_tdep_is_fpreg (int);
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#define unw_tdep_make_frame_cache(n) (0)
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#define unw_tdep_free_frame_cache(p) do {} while(0)
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#define unw_tdep_trace(cur,addr,n,c) (-UNW_ENOINFO)
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#if defined(__cplusplus) || defined(c_plusplus)
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@ -130,17 +130,12 @@ unw_tdep_frame_t;
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#define unw_tdep_getcontext UNW_ARCH_OBJ(getcontext)
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#define unw_tdep_is_fpreg UNW_ARCH_OBJ(is_fpreg)
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#define unw_tdep_make_frame_cache UNW_OBJ(make_frame_cache)
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#define unw_tdep_free_frame_cache UNW_OBJ(free_frame_cache)
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#define unw_tdep_trace UNW_OBJ(trace)
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extern int unw_tdep_getcontext (unw_tdep_context_t *);
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extern int unw_tdep_is_fpreg (int);
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extern unw_tdep_frame_t *unw_tdep_make_frame_cache (size_t n);
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extern int unw_tdep_free_frame_cache (unw_tdep_frame_t *p);
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extern int unw_tdep_trace (unw_cursor_t *cursor, void **addresses,
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int *n, unw_tdep_frame_t *cache);
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extern int unw_tdep_trace (unw_cursor_t *cursor, void **addresses, int *n);
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#if defined(__cplusplus) || defined(c_plusplus)
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}
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@ -27,30 +27,38 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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#define UNW_LOCAL_ONLY
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#include <libunwind.h>
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#include <string.h>
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/* See glibc manual for a description of this function. */
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int
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backtrace (void **buffer, int size)
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unw_backtrace (void **buffer, int size)
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{
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unw_cursor_t cursor;
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unw_context_t uc;
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unw_word_t ip;
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int n = 0;
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unw_context_t uc, ucsave;
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int n = size;
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unw_getcontext (&uc);
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memcpy (&ucsave, &uc, sizeof(uc));
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if (unw_init_local (&cursor, &uc) < 0)
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return 0;
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while (unw_step (&cursor) > 0)
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if (unw_tdep_trace (&cursor, buffer, &n) < 0)
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{
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if (n >= size)
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return n;
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if (unw_get_reg (&cursor, UNW_REG_IP, &ip) < 0)
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return n;
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buffer[n++] = (void *) (uintptr_t) ip;
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n = 0;
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unw_init_local (&cursor, &ucsave);
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while (n < size)
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{
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unw_word_t ip;
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if (unw_get_reg (&cursor, UNW_REG_IP, &ip) < 0)
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return n;
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buffer[n++] = (void *) (uintptr_t) ip;
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if (unw_step (&cursor) <= 0)
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break;
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}
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}
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return n;
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}
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@ -26,16 +26,15 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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#include "ucontext_i.h"
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#include <signal.h>
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/* Utility for timing in debug mode. You'll probably want to
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comment out all unnecessary debugging in this file if you
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use this, otherwise the timings printed will not make sense. */
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#if UNW_DEBUG
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#define rdtsc(v) \
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do { unsigned lo, hi; \
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__asm__ volatile ("rdtsc" : "=a" (lo), "=d" (hi)); \
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(v) = ((unsigned long) lo) | ((unsigned long) hi << 32); \
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} while (0)
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#endif
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#pragma weak pthread_once
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#pragma weak pthread_key_create
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#pragma weak pthread_getspecific
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#pragma weak pthread_setspecific
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/* Total maxium hash table size is 16M addresses. HASH_TOP_BITS must
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be a power of four, as the hash expands by four each time. */
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#define HASH_LOW_BITS 14
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#define HASH_TOP_BITS 10
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/* There's not enough space to store RIP's location in a signal
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frame, but we can calculate it relative to RBP's (or RSP's)
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@ -43,43 +42,157 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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the UC_MCONTEXT_GREGS_* directly since we rely on DWARF info. */
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#define dRIP (UC_MCONTEXT_GREGS_RIP - UC_MCONTEXT_GREGS_RBP)
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/* Allocate and initialise hash table for frame cache lookups.
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Client requests size N, which should be 5 to 10 more than expected
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number of unique addresses to trace. Minimum size of 10000 is
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forced. Returns the cache, or NULL if there was a memory
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allocation problem. */
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unw_tdep_frame_t *
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unw_tdep_make_frame_cache (size_t n)
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typedef struct
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{
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size_t i;
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unw_tdep_frame_t *cache;
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unw_tdep_frame_t *frames[1u << HASH_TOP_BITS];
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size_t log_frame_vecs;
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size_t used;
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} unw_trace_cache_t;
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if (n < 10000)
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n = 10000;
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static const unw_tdep_frame_t empty_frame = { 0, UNW_X86_64_FRAME_OTHER, -1, -1, 0, -1, -1 };
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static pthread_mutex_t trace_init_lock = PTHREAD_MUTEX_INITIALIZER;
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static pthread_once_t trace_cache_once = PTHREAD_ONCE_INIT;
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static pthread_key_t trace_cache_key;
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static struct mempool trace_cache_pool;
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static struct mempool trace_frame_pool;
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if (! (cache = malloc((n+1) * sizeof(unw_tdep_frame_t))))
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return 0;
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unw_tdep_frame_t empty = { 0, UNW_X86_64_FRAME_OTHER, -1, -1, 0, -1, -1 };
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for (i = 0; i < n; ++i)
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cache[i] = empty;
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cache[0].virtual_address = n;
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return cache+1;
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/* Initialise memory pools for frame tracing. */
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static void
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trace_pools_init (void)
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{
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mempool_init (&trace_cache_pool, sizeof (unw_trace_cache_t), 0);
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mempool_init (&trace_frame_pool, (1u << HASH_LOW_BITS) * sizeof (unw_tdep_frame_t), 0);
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}
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/* Free the address cache allocated by unw_tdep_make_frame_cache().
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Returns 0 on success, or -UNW_EINVAL if cache was NULL. */
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int
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unw_tdep_free_frame_cache (unw_tdep_frame_t *cache)
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/* Free memory for a thread's trace cache. */
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static void
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trace_cache_free (void *arg)
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{
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if (! cache)
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return -UNW_EINVAL;
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unw_trace_cache_t *cache = arg;
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size_t i;
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free(cache-1);
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for (i = 0; i < (1u << cache->log_frame_vecs); ++i)
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mempool_free (&trace_frame_pool, cache->frames[i]);
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mempool_free (&trace_cache_pool, cache);
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Debug(5, "freed cache %p\n", cache);
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}
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/* Initialise frame tracing for threaded use. */
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static void
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trace_cache_init_once (void)
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{
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pthread_key_create (&trace_cache_key, &trace_cache_free);
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trace_pools_init ();
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}
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static unw_tdep_frame_t *
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trace_cache_buckets (void)
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{
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unw_tdep_frame_t *frames = mempool_alloc(&trace_frame_pool);
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size_t i;
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if (likely (frames != 0))
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for (i = 0; i < (1u << HASH_LOW_BITS); ++i)
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frames[i] = empty_frame;
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return frames;
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}
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/* Allocate and initialise hash table for frame cache lookups.
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Returns the cache initialised with (1u << HASH_LOW_BITS) hash
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buckets, or NULL if there was a memory allocation problem. */
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static unw_trace_cache_t *
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trace_cache_create (void)
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{
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unw_trace_cache_t *cache;
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if (! (cache = mempool_alloc(&trace_cache_pool)))
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{
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Debug(5, "failed to allocate cache\n");
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return 0;
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}
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memset(cache, 0, sizeof (*cache));
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if (! (cache->frames[0] = trace_cache_buckets()))
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{
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Debug(5, "failed to allocate buckets\n");
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mempool_free(&trace_cache_pool, cache);
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return 0;
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}
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cache->log_frame_vecs = 0;
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cache->used = 0;
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Debug(5, "allocated cache %p\n", cache);
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return cache;
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}
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/* Expand the hash table in the frame cache if possible. This always
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quadruples the hash size, and clears all previous frame entries. */
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static int
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trace_cache_expand (unw_trace_cache_t *cache)
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{
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size_t i, j, new_size, old_size;
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if (cache->log_frame_vecs == HASH_TOP_BITS)
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{
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Debug(5, "cache already at maximum size, cannot expand\n");
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return -UNW_ENOMEM;
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}
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old_size = (1u << cache->log_frame_vecs);
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new_size = cache->log_frame_vecs + 2;
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for (i = old_size; i < (1u << new_size); ++i)
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if (unlikely (! (cache->frames[i] = trace_cache_buckets())))
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{
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Debug(5, "failed to expand cache to 2^%lu hash bucket sets\n", new_size);
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for (j = old_size; j < i; ++j)
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mempool_free(&trace_frame_pool, cache->frames[j]);
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return -UNW_ENOMEM;
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}
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for (i = 0; i < old_size; ++i)
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for (j = 0; j < (1u << HASH_LOW_BITS); ++j)
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cache->frames[i][j] = empty_frame;
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Debug(5, "expanded cache from 2^%lu to 2^%lu hash bucket sets\n",
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cache->log_frame_vecs, new_size);
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cache->log_frame_vecs = new_size;
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return 0;
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}
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/* Get the frame cache for the current thread. Create it if there is none. */
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static unw_trace_cache_t *
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trace_cache_get (void)
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{
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unw_trace_cache_t *cache;
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if (pthread_once)
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{
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pthread_once(&trace_cache_once, &trace_cache_init_once);
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if (! (cache = pthread_getspecific(trace_cache_key)))
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{
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cache = trace_cache_create();
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pthread_setspecific(trace_cache_key, cache);
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}
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Debug(5, "using cache %p\n", cache);
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return cache;
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}
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else
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{
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intrmask_t saved_mask;
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static unw_trace_cache_t *global_cache = 0;
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lock_acquire (&trace_init_lock, saved_mask);
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if (! global_cache)
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{
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trace_pools_init();
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global_cache = trace_cache_create();
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}
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cache = global_cache;
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lock_release (&trace_init_lock, saved_mask);
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Debug(5, "using cache %p\n", cache);
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return cache;
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}
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}
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/* Initialise frame properties for address cache slot F at address
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RIP using current CFA, RBP and RSP values. Modifies CURSOR to
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that location, performs one unw_step(), and fills F with what
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@ -149,7 +262,7 @@ trace_init_addr (unw_tdep_frame_t *f,
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frame cache slot which describes RIP. */
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static unw_tdep_frame_t *
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trace_lookup (unw_cursor_t *cursor,
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unw_tdep_frame_t *cache,
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unw_trace_cache_t *cache,
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unw_word_t cfa,
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unw_word_t rip,
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unw_word_t rbp,
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@ -160,20 +273,23 @@ trace_lookup (unw_cursor_t *cursor,
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lookups should be completed within few steps, but it is very
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important the hash table does not fill up, or performance falls
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off the cliff. */
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uint64_t cache_size = cache[-1].virtual_address;
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uint64_t probe_steps = (cache_size >> 5);
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uint64_t slot = ((rip * 0x9e3779b97f4a7c16) >> 43) % cache_size;
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uint64_t i;
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uint64_t i, hi, lo, addr;
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uint64_t cache_size = 1u << (HASH_LOW_BITS + cache->log_frame_vecs);
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uint64_t slot = ((rip * 0x9e3779b97f4a7c16) >> 43) & (cache_size-1);
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unw_tdep_frame_t *frame;
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for (i = 0; i < probe_steps; ++i)
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for (i = 0; i < 16; ++i)
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{
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uint64_t addr = cache[slot].virtual_address;
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lo = slot & ((1u << HASH_LOW_BITS) - 1);
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hi = slot >> HASH_LOW_BITS;
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frame = &cache->frames[hi][lo];
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addr = frame->virtual_address;
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/* Return if we found the address. */
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if (addr == rip)
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{
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Debug (4, "found address after %ld steps\n", i);
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return &cache[slot];
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return frame;
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}
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/* If slot is empty, reuse it. */
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@ -181,13 +297,32 @@ trace_lookup (unw_cursor_t *cursor,
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break;
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/* Linear probe to next slot candidate, step = 1. */
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if (++slot > cache_size)
|
||||
if (++slot >= cache_size)
|
||||
slot -= cache_size;
|
||||
}
|
||||
|
||||
/* Fill this slot, whether it's free or hash collision. */
|
||||
Debug (4, "updating slot after %ld steps\n", i);
|
||||
return trace_init_addr (&cache[slot], cursor, cfa, rip, rbp, rsp);
|
||||
/* If we collided after 16 steps, or if the hash is more than half
|
||||
full, force the hash to expand. Fill the selected slot, whether
|
||||
it's free or collides. Note that hash expansion drops previous
|
||||
contents; further lookups will refill the hash. */
|
||||
Debug (4, "updating slot %lu after %ld steps, replacing 0x%lx\n", slot, i, addr);
|
||||
if (unlikely (addr || cache->used >= cache_size / 2))
|
||||
{
|
||||
if (unlikely (trace_cache_expand (cache) < 0))
|
||||
return 0;
|
||||
|
||||
cache_size = 1u << (HASH_LOW_BITS + cache->log_frame_vecs);
|
||||
slot = ((rip * 0x9e3779b97f4a7c16) >> 43) & (cache_size-1);
|
||||
lo = slot & ((1u << HASH_LOW_BITS) - 1);
|
||||
hi = slot >> HASH_LOW_BITS;
|
||||
frame = &cache->frames[hi][lo];
|
||||
addr = frame->virtual_address;
|
||||
}
|
||||
|
||||
if (! addr)
|
||||
++cache->used;
|
||||
|
||||
return trace_init_addr (frame, cursor, cfa, rip, rbp, rsp);
|
||||
}
|
||||
|
||||
/* Fast stack backtrace for x86-64.
|
||||
|
|
@ -197,8 +332,8 @@ trace_lookup (unw_cursor_t *cursor,
|
|||
GLIBC backtrace() function: fills BUFFER with the call tree from
|
||||
CURSOR upwards, and SIZE with the number of stack levels so found.
|
||||
When called, SIZE should tell the maximum number of entries that
|
||||
can be stored in BUFFER. CACHE is used to accelerate the stack
|
||||
queries; no other thread may use the same cache concurrently.
|
||||
can be stored in BUFFER. An internal thread-specific cache is used
|
||||
to accelerate the stack queries.
|
||||
|
||||
The caller should fall back to a unw_step() loop if this function
|
||||
fails by returning -UNW_ESTOPUNWIND, meaning the routine hit a
|
||||
|
|
@ -234,7 +369,6 @@ trace_lookup (unw_cursor_t *cursor,
|
|||
|
||||
unw_cursor_t cur;
|
||||
unw_context_t ctx, saved;
|
||||
unw_tdep_frame_t *cache = ...;
|
||||
void addrs[128];
|
||||
int depth = 128;
|
||||
int ret;
|
||||
|
|
@ -243,7 +377,7 @@ trace_lookup (unw_cursor_t *cursor,
|
|||
memcpy(&saved, &ctx, sizeof(ctx));
|
||||
|
||||
unw_init_local(&cur, &ctx);
|
||||
if (! cache || (ret = unw_tdep_trace(&cur, addrs, &depth, cache)) < 0)
|
||||
if ((ret = unw_tdep_trace(&cur, addrs, &depth)) < 0)
|
||||
{
|
||||
depth = 0;
|
||||
unw_init_local(&cur, &saved);
|
||||
|
|
@ -258,24 +392,18 @@ trace_lookup (unw_cursor_t *cursor,
|
|||
}
|
||||
*/
|
||||
int
|
||||
unw_tdep_trace (unw_cursor_t *cursor,
|
||||
void **buffer,
|
||||
int *size,
|
||||
unw_tdep_frame_t *cache)
|
||||
unw_tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
|
||||
{
|
||||
struct cursor *c = (struct cursor *) cursor;
|
||||
struct dwarf_cursor *d = &c->dwarf;
|
||||
unw_trace_cache_t *cache;
|
||||
unw_word_t rbp, rsp, rip, cfa;
|
||||
int maxdepth = 0;
|
||||
int depth = 0;
|
||||
int ret;
|
||||
#if UNW_DEBUG
|
||||
unsigned long start, end;
|
||||
rdtsc(start);
|
||||
#endif
|
||||
|
||||
/* Check input parametres. */
|
||||
if (! cursor || ! buffer || ! size || ! cache || (maxdepth = *size) <= 0)
|
||||
if (! cursor || ! buffer || ! size || (maxdepth = *size) <= 0)
|
||||
return -UNW_EINVAL;
|
||||
|
||||
Debug (1, "begin ip 0x%lx cfa 0x%lx\n", d->ip, d->cfa);
|
||||
|
|
@ -288,10 +416,21 @@ unw_tdep_trace (unw_cursor_t *cursor,
|
|||
rsp = cfa = d->cfa;
|
||||
if ((ret = dwarf_get (d, d->loc[UNW_X86_64_RBP], &rbp)) < 0)
|
||||
{
|
||||
Debug (1, "returning %d, rbp value not found\n", ret);
|
||||
*size = 0;
|
||||
d->stash_frames = 0;
|
||||
return ret;
|
||||
}
|
||||
|
||||
/* Get frame cache. */
|
||||
if (! (cache = trace_cache_get()))
|
||||
{
|
||||
Debug (1, "returning %d, cannot get trace cache\n", -UNW_ENOMEM);
|
||||
*size = 0;
|
||||
d->stash_frames = 0;
|
||||
return -UNW_ENOMEM;
|
||||
}
|
||||
|
||||
/* Trace the stack upwards, starting from current RIP. Adjust
|
||||
the RIP address for previous/next instruction as the main
|
||||
unwinding logic would also do. We undo this before calling
|
||||
|
|
@ -393,8 +532,7 @@ unw_tdep_trace (unw_cursor_t *cursor,
|
|||
}
|
||||
|
||||
#if UNW_DEBUG
|
||||
rdtsc(end);
|
||||
Debug (1, "returning %d depth %d, dt=%ld\n", ret, depth, end - start);
|
||||
Debug (1, "returning %d, depth %d\n", ret, depth);
|
||||
#endif
|
||||
*size = depth;
|
||||
return ret;
|
||||
|
|
|
|||
Loading…
Reference in a new issue