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#ifndef _STACK_C_ /* -*- linux-c -*- */
#define _STACK_C_
/** @file stack.c
* @brief Stack Tracing Functions
*/
/** @addtogroup stack Stack Tracing Functions
* Without frames the best that can be done here is to scan the stack and
* display everything that fits in the range of a valid IP. Things like function pointers
* on the stack will certainly result in bogus addresses in the backtrace.
*
* With debug info, we could get a proper backtrace, but it would be too slow to do
* during a probe. We can eventually make this a postprocessing feature.
*
* @{
*/
#include "sym.c"
#include "regs.h"
#if defined (__x86_64__)
static void __stp_stack_sprint (String str, unsigned long *stack, int verbose, int levels)
{
unsigned long addr;
while (((long) stack & (THREAD_SIZE-1)) != 0) {
addr = *stack++;
if (_stp_kta(addr)) {
if (verbose) {
_stp_string_cat(str, " ");
_stp_symbol_sprint (str, addr);
_stp_string_cat (str, "\n");
} else
_stp_sprintf (str, "%lx ", addr);
}
}
}
#elif defined (__i386__)
static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
{
return p > (void *)tinfo &&
p < (void *)tinfo + THREAD_SIZE - 3;
}
static inline unsigned long print_context_stack(String str, struct thread_info *tinfo,
unsigned long *stack, unsigned long ebp, int verbose)
{
unsigned long addr;
#ifdef CONFIG_FRAME_POINTER
while (valid_stack_ptr(tinfo, (void *)ebp)) {
addr = *(unsigned long *)(ebp + 4);
if (verbose) {
_stp_string_cat(str, " ");
_stp_symbol_sprint (str, addr);
_stp_string_cat(str, "\n");
} else
_stp_sprintf (str, "%lx ", addr);
ebp = *(unsigned long *)ebp;
}
#else
while (valid_stack_ptr(tinfo, stack)) {
addr = *stack++;
if (_stp_kta(addr)) {
if (verbose) {
_stp_string_cat(str, " ");
_stp_symbol_sprint(str, addr);
_stp_string_cat(str, "\n");
} else
_stp_sprintf (str, "%lx ", addr);
}
}
#endif
return ebp;
}
static void __stp_stack_sprint (String str, unsigned long *stack, int verbose, int levels)
{
unsigned long ebp;
/* Grab ebp right from our regs */
asm ("movl %%ebp, %0" : "=r" (ebp) : );
while (1) {
struct thread_info *context;
context = (struct thread_info *)
((unsigned long)stack & (~(THREAD_SIZE - 1)));
ebp = print_context_stack(str, context, stack, ebp, verbose);
stack = (unsigned long*)context->previous_esp;
if (!stack)
break;
}
}
#else
#error "Unsupported architecture"
#endif
/** Writes stack backtrace to a String
*
* @param str String
* @param regs A pointer to the struct pt_regs.
* @returns Same String as was input with trace info appended,
*/
String _stp_stack_sprint (String str, struct pt_regs *regs, int verbose)
{
if (verbose) {
_stp_sprintf (str, "trace for %d (%s)\n ", current->pid, current->comm);
_stp_symbol_sprint (str, REG_IP(regs));
_stp_string_cat(str, "\n");
} else
_stp_sprintf (str, "%lx ", REG_IP(regs));
__stp_stack_sprint (str, (unsigned long *)®_SP(regs), verbose, 0);
return str;
}
/** Prints the stack backtrace
* @param regs A pointer to the struct pt_regs.
*/
#define _stp_stack_print(regs) (void)_stp_stack_sprint(_stp_stdout,regs,1)
/** Writes stack backtrace to a String.
* Use this when calling from a jprobe.
* @param str String
* @returns Same String as was input with trace info appended,
* @sa _stp_stack_sprint()
*/
String _stp_stack_sprintj(String str)
{
unsigned long stack;
_stp_sprintf (str, "trace for %d (%s)\n", current->pid, current->comm);
__stp_stack_sprint (str, &stack, 1, 0);
return str;
}
/** Prints the stack backtrace.
* Use this when calling from a jprobe.
* @sa _stp_stack_print()
*/
#define _stp_stack_printj() (void)_stp_stack_sprintj(_stp_stdout)
/** Writes the user stack backtrace to a String
* @param str String
* @returns Same String as was input with trace info appended,
* @note Currently limited to a depth of two. Works from jprobes and kprobes.
*/
String _stp_ustack_sprint (String str)
{
struct pt_regs *nregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) current->thread_info)) - 1;
#if BITS_PER_LONG == 64
_stp_sprintf (str, " 0x%016lx : [user]\n", REG_IP(nregs));
if (REG_SP(nregs))
_stp_sprintf (str, " 0x%016lx : [user]\n", *(unsigned long *)REG_SP(nregs));
#else
_stp_sprintf (str, " 0x%08lx : [user]\n", REG_IP(nregs));
if (REG_SP(nregs))
_stp_sprintf (str, " 0x%08lx : [user]\n", *(unsigned long *)REG_SP(nregs));
#endif
return str;
}
/** Prints the user stack backtrace
* @note Currently limited to a depth of two. Works from jprobes and kprobes.
*/
#define _stp_ustack_print() (void)_stp_ustack_sprint(_stp_stdout)
/** @} */
#endif /* _STACK_C_ */
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