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ftmemsim-valgrind/coregrind/m_stacktrace.c
Julian Seward 35c28b721f Merge Helgrind from branches/YARD into the trunk. Also includes some 
minor changes to make stack unwinding on amd64-linux approximately
twice as fast as it was before.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@8707
2008-10-25 16:22:41 +00:00

577 lines
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/*--------------------------------------------------------------------*/
/*--- Take snapshots of client stacks. m_stacktrace.c ---*/
/*--------------------------------------------------------------------*/
/*
This file is part of Valgrind, a dynamic binary instrumentation
framework.
Copyright (C) 2000-2008 Julian Seward
jseward@acm.org
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307, USA.
The GNU General Public License is contained in the file COPYING.
*/
#include "pub_core_basics.h"
#include "pub_core_vki.h"
#include "pub_core_threadstate.h"
#include "pub_core_debuginfo.h"
#include "pub_core_aspacemgr.h" // For VG_(is_addressable)()
#include "pub_core_libcbase.h"
#include "pub_core_libcassert.h"
#include "pub_core_libcprint.h"
#include "pub_core_machine.h"
#include "pub_core_options.h"
#include "pub_core_stacks.h" // VG_(stack_limits)
#include "pub_core_stacktrace.h"
#include "pub_core_xarray.h"
#include "pub_core_clientstate.h" // VG_(client__dl_sysinfo_int80)
#include "pub_core_trampoline.h"
/*------------------------------------------------------------*/
/*--- Exported functions. ---*/
/*------------------------------------------------------------*/
/* Take a snapshot of the client's stack, putting the up to 'n_ips'
IPs into 'ips'. In order to be thread-safe, we pass in the
thread's IP SP, FP if that's meaningful, and LR if that's
meaningful. Returns number of IPs put in 'ips'.
If you know what the thread ID for this stack is, send that as the
first parameter, else send zero. This helps generate better stack
traces on ppc64-linux and has no effect on other platforms.
*/
UInt VG_(get_StackTrace_wrk) ( ThreadId tid_if_known,
/*OUT*/Addr* ips, UInt n_ips,
/*OUT*/Addr* sps, /*OUT*/Addr* fps,
Addr ip, Addr sp, Addr fp, Addr lr,
Addr fp_min, Addr fp_max_orig )
{
# if defined(VGP_ppc32_linux) || defined(VGP_ppc64_linux) \
|| defined(VGP_ppc32_aix5) \
|| defined(VGP_ppc64_aix5)
Bool lr_is_first_RA = False;
# endif
# if defined(VGP_ppc64_linux) || defined(VGP_ppc64_aix5) \
|| defined(VGP_ppc32_aix5)
Word redir_stack_size = 0;
Word redirs_used = 0;
# endif
Bool debug = False;
Int i;
Addr fp_max;
UInt n_found = 0;
vg_assert(sizeof(Addr) == sizeof(UWord));
vg_assert(sizeof(Addr) == sizeof(void*));
/* Snaffle IPs from the client's stack into ips[0 .. n_ips-1],
stopping when the trail goes cold, which we guess to be
when FP is not a reasonable stack location. */
// JRS 2002-sep-17: hack, to round up fp_max to the end of the
// current page, at least. Dunno if it helps.
// NJN 2002-sep-17: seems to -- stack traces look like 1.0.X again
fp_max = VG_PGROUNDUP(fp_max_orig);
if (fp_max >= sizeof(Addr))
fp_max -= sizeof(Addr);
if (debug)
VG_(printf)("n_ips=%d fp_min=0x%lx fp_max_orig=0x%lx, "
"fp_max=0x%lx ip=0x%lx fp=0x%lx\n",
n_ips, fp_min, fp_max_orig, fp_max, ip, fp);
/* Assertion broken before main() is reached in pthreaded programs; the
* offending stack traces only have one item. --njn, 2002-aug-16 */
/* vg_assert(fp_min <= fp_max);*/
if (fp_min + 512 >= fp_max) {
/* If the stack limits look bogus, don't poke around ... but
don't bomb out either. */
if (sps) sps[0] = sp;
if (fps) fps[0] = fp;
ips[0] = ip;
return 1;
}
/* Otherwise unwind the stack in a platform-specific way. Trying
to merge the x86, amd64, ppc32 and ppc64 logic into a single
piece of code is just too confusing and difficult to
performance-tune. */
# if defined(VGP_x86_linux)
/*--------------------- x86 ---------------------*/
/* fp is %ebp. sp is %esp. ip is %eip. */
if (sps) sps[0] = sp;
if (fps) fps[0] = fp;
ips[0] = ip;
i = 1;
/* Loop unwinding the stack. Note that the IP value we get on
* each pass (whether from CFI info or a stack frame) is a
* return address so is actually after the calling instruction
* in the calling function.
*
* Because of this we subtract one from the IP after each pass
* of the loop so that we find the right CFI block on the next
* pass - otherwise we can find the wrong CFI info if it happens
* to change after the calling instruction and that will mean
* that we will fail to unwind the next step.
*
* This most frequently happens at the end of a function when
* a tail call occurs and we wind up using the CFI info for the
* next function which is completely wrong.
*
* Note that VG_(get_data_description) (in m_debuginfo) has to take
* this same problem into account when unwinding the stack to
* examine local variable descriptions (as documented therein in
* comments).
*/
while (True) {
if (i >= n_ips)
break;
/* Try to derive a new (ip,sp,fp) triple from the current
set. */
/* On x86, first try the old-fashioned method of following the
%ebp-chain. Code which doesn't use this (that is, compiled
with -fomit-frame-pointer) is not ABI compliant and so
relatively rare. Besides, trying the CFI first almost always
fails, and is expensive. */
/* Deal with frames resulting from functions which begin "pushl%
ebp ; movl %esp, %ebp" which is the ABI-mandated preamble. */
if (fp_min <= fp && fp <= fp_max
- 1 * sizeof(UWord)/*see comment below*/) {
/* fp looks sane, so use it. */
ip = (((UWord*)fp)[1]);
sp = fp + sizeof(Addr) /*saved %ebp*/
+ sizeof(Addr) /*ra*/;
fp = (((UWord*)fp)[0]);
if (sps) sps[i] = sp;
if (fps) fps[i] = fp;
ips[i++] = ip;
if (debug)
VG_(printf)(" ipsF[%d]=0x%08lx\n", i-1, ips[i-1]);
ip = ip - 1;
continue;
}
/* That didn't work out, so see if there is any CF info to hand
which can be used. */
if ( VG_(use_CF_info)( &ip, &sp, &fp, fp_min, fp_max ) ) {
if (sps) sps[i] = sp;
if (fps) fps[i] = fp;
ips[i++] = ip;
if (debug)
VG_(printf)(" ipsC[%d]=0x%08lx\n", i-1, ips[i-1]);
ip = ip - 1;
continue;
}
/* No luck. We have to give up. */
break;
}
# elif defined(VGP_amd64_linux)
/*--------------------- amd64 ---------------------*/
/* fp is %rbp. sp is %rsp. ip is %rip. */
ips[0] = ip;
if (sps) sps[0] = sp;
if (fps) fps[0] = fp;
i = 1;
/* Loop unwinding the stack. Note that the IP value we get on
* each pass (whether from CFI info or a stack frame) is a
* return address so is actually after the calling instruction
* in the calling function.
*
* Because of this we subtract one from the IP after each pass
* of the loop so that we find the right CFI block on the next
* pass - otherwise we can find the wrong CFI info if it happens
* to change after the calling instruction and that will mean
* that we will fail to unwind the next step.
*
* This most frequently happens at the end of a function when
* a tail call occurs and we wind up using the CFI info for the
* next function which is completely wrong.
*
* Note that VG_(get_data_description) (in m_debuginfo) has to take
* this same problem into account when unwinding the stack to
* examine local variable descriptions (as documented therein in
* comments).
*/
while (True) {
if (i >= n_ips)
break;
/* Try to derive a new (ip,sp,fp) triple from the current
set. */
/* First off, see if there is any CFI info to hand which can
be used. */
if ( VG_(use_CF_info)( &ip, &sp, &fp, fp_min, fp_max ) ) {
if (sps) sps[i] = sp;
if (fps) fps[i] = fp;
ips[i++] = ip;
if (debug)
VG_(printf)(" ipsC[%d]=%#08lx\n", i-1, ips[i-1]);
ip = ip - 1;
continue;
}
/* If VG_(use_CF_info) fails, it won't modify ip/sp/fp, so
we can safely try the old-fashioned method. */
/* This bit is supposed to deal with frames resulting from
functions which begin "pushq %rbp ; movq %rsp, %rbp".
Unfortunately, since we can't (easily) look at the insns at
the start of the fn, like GDB does, there's no reliable way
to tell. Hence the hack of first trying out CFI, and if that
fails, then use this as a fallback. */
/* Note: re "- 1 * sizeof(UWord)", need to take account of the
fact that we are prodding at & ((UWord*)fp)[1] and so need to
adjust the limit check accordingly. Omitting this has been
observed to cause segfaults on rare occasions. */
if (fp_min <= fp && fp <= fp_max - 1 * sizeof(UWord)) {
/* fp looks sane, so use it. */
ip = (((UWord*)fp)[1]);
sp = fp + sizeof(Addr) /*saved %rbp*/
+ sizeof(Addr) /*ra*/;
fp = (((UWord*)fp)[0]);
if (sps) sps[i] = sp;
if (fps) fps[i] = fp;
ips[i++] = ip;
if (debug)
VG_(printf)(" ipsF[%d]=%#08lx\n", i-1, ips[i-1]);
ip = ip - 1;
continue;
}
/* Last-ditch hack (evidently GDB does something similar). We
are in the middle of nowhere and we have a nonsense value for
the frame pointer. If the stack pointer is still valid,
assume that what it points at is a return address. Yes,
desperate measures. Could do better here:
- check that the supposed return address is in
an executable page
- check that the supposed return address is just after a call insn
- given those two checks, don't just consider *sp as the return
address; instead scan a likely section of stack (eg sp .. sp+256)
and use suitable values found there.
*/
if (fp_min <= sp && sp < fp_max) {
ip = ((UWord*)sp)[0];
if (sps) sps[i] = sp;
if (fps) fps[i] = fp;
ips[i++] = ip;
if (debug)
VG_(printf)(" ipsH[%d]=%#08lx\n", i-1, ips[i-1]);
ip = ip - 1;
sp += 8;
continue;
}
/* No luck at all. We have to give up. */
break;
}
# elif defined(VGP_ppc32_linux) || defined(VGP_ppc64_linux) \
|| defined(VGP_ppc32_aix5) || defined(VGP_ppc64_aix5)
/*--------------------- ppc32/64 ---------------------*/
/* fp is %r1. ip is %cia. Note, ppc uses r1 as both the stack and
frame pointers. */
# if defined(VGP_ppc64_linux) || defined(VGP_ppc64_aix5)
redir_stack_size = VEX_GUEST_PPC64_REDIR_STACK_SIZE;
redirs_used = 0;
# elif defined(VGP_ppc32_aix5)
redir_stack_size = VEX_GUEST_PPC32_REDIR_STACK_SIZE;
redirs_used = 0;
# endif
# if defined(VG_PLAT_USES_PPCTOC)
/* Deal with bogus LR values caused by function
interception/wrapping on ppc-TOC platforms; see comment on
similar code a few lines further down. */
if (ULong_to_Ptr(lr) == (void*)&VG_(ppctoc_magic_redirect_return_stub)
&& VG_(is_valid_tid)(tid_if_known)) {
Word hsp = VG_(threads)[tid_if_known].arch.vex.guest_REDIR_SP;
redirs_used++;
if (hsp >= 1 && hsp < redir_stack_size)
lr = VG_(threads)[tid_if_known]
.arch.vex.guest_REDIR_STACK[hsp-1];
}
# endif
/* We have to determine whether or not LR currently holds this fn
(call it F)'s return address. It might not if F has previously
called some other function, hence overwriting LR with a pointer
to some part of F. Hence if LR and IP point to the same
function then we conclude LR does not hold this function's
return address; instead the LR at entry must have been saved in
the stack by F's prologue and so we must get it from there
instead. Note all this guff only applies to the innermost
frame. */
lr_is_first_RA = False;
{
# define M_VG_ERRTXT 1000
UChar buf_lr[M_VG_ERRTXT], buf_ip[M_VG_ERRTXT];
if (VG_(get_fnname_nodemangle) (lr, buf_lr, M_VG_ERRTXT))
if (VG_(get_fnname_nodemangle) (ip, buf_ip, M_VG_ERRTXT))
if (VG_(strncmp)(buf_lr, buf_ip, M_VG_ERRTXT))
lr_is_first_RA = True;
# undef M_VG_ERRTXT
}
if (sps) sps[0] = fp; /* NB. not sp */
if (fps) fps[0] = fp;
ips[0] = ip;
i = 1;
if (fp_min <= fp && fp < fp_max-VG_WORDSIZE+1) {
/* initial FP is sane; keep going */
fp = (((UWord*)fp)[0]);
while (True) {
/* On ppc64-linux (ppc64-elf, really), and on AIX, the lr save
slot is 2 words back from sp, whereas on ppc32-elf(?) it's
only one word back. */
# if defined(VGP_ppc64_linux) \
|| defined(VGP_ppc32_aix5) || defined(VGP_ppc64_aix5)
const Int lr_offset = 2;
# else
const Int lr_offset = 1;
# endif
if (i >= n_ips)
break;
/* Try to derive a new (ip,fp) pair from the current set. */
if (fp_min <= fp && fp <= fp_max - lr_offset * sizeof(UWord)) {
/* fp looks sane, so use it. */
if (i == 1 && lr_is_first_RA)
ip = lr;
else
ip = (((UWord*)fp)[lr_offset]);
# if defined(VG_PLAT_USES_PPCTOC)
/* Nasty hack to do with function replacement/wrapping on
ppc64-linux/ppc64-aix/ppc32-aix. If LR points to our
magic return stub, then we are in a wrapped or
intercepted function, in which LR has been messed with.
The original LR will have been pushed onto the thread's
hidden REDIR stack one down from the top (top element
is the saved R2) and so we should restore the value
from there instead. Since nested redirections can and
do happen, we keep track of the number of nested LRs
used by the unwinding so far with 'redirs_used'. */
if (ip == (Addr)&VG_(ppctoc_magic_redirect_return_stub)
&& VG_(is_valid_tid)(tid_if_known)) {
Word hsp = VG_(threads)[tid_if_known]
.arch.vex.guest_REDIR_SP;
hsp -= 2 * redirs_used;
redirs_used ++;
if (hsp >= 1 && hsp < redir_stack_size)
ip = VG_(threads)[tid_if_known]
.arch.vex.guest_REDIR_STACK[hsp-1];
}
# endif
fp = (((UWord*)fp)[0]);
if (sps) sps[i] = fp; /* NB. not sp */
if (fps) fps[i] = fp;
ips[i++] = ip;
if (debug)
VG_(printf)(" ipsF[%d]=%#08lx\n", i-1, ips[i-1]);
continue;
}
/* No luck there. We have to give up. */
break;
}
}
# else
# error "Unknown platform"
# endif
n_found = i;
return n_found;
}
UInt VG_(get_StackTrace) ( ThreadId tid,
/*OUT*/StackTrace ips, UInt n_ips,
/*OUT*/StackTrace sps,
/*OUT*/StackTrace fps,
Word first_ip_delta )
{
/* thread in thread table */
Addr ip = VG_(get_IP)(tid);
Addr fp = VG_(get_FP)(tid);
Addr sp = VG_(get_SP)(tid);
Addr lr = VG_(get_LR)(tid);
Addr stack_highest_word = VG_(threads)[tid].client_stack_highest_word;
Addr stack_lowest_word = 0;
# if defined(VGP_x86_linux)
/* Nasty little hack to deal with syscalls - if libc is using its
_dl_sysinfo_int80 function for syscalls (the TLS version does),
then ip will always appear to be in that function when doing a
syscall, not the actual libc function doing the syscall. This
check sees if IP is within that function, and pops the return
address off the stack so that ip is placed within the library
function calling the syscall. This makes stack backtraces much
more useful.
The function is assumed to look like this (from glibc-2.3.6 sources):
_dl_sysinfo_int80:
int $0x80
ret
That is 3 (2+1) bytes long. We could be more thorough and check
the 3 bytes of the function are as expected, but I can't be
bothered.
*/
if (VG_(client__dl_sysinfo_int80) != 0 /* we know its address */
&& ip >= VG_(client__dl_sysinfo_int80)
&& ip < VG_(client__dl_sysinfo_int80)+3
&& VG_(am_is_valid_for_client)(sp, sizeof(Addr), VKI_PROT_READ)) {
ip = *(Addr *)sp;
sp += sizeof(Addr);
}
# endif
/* See if we can get a better idea of the stack limits */
VG_(stack_limits)(sp, &stack_lowest_word, &stack_highest_word);
/* Take into account the first_ip_delta. */
vg_assert( sizeof(Addr) == sizeof(Word) );
ip += first_ip_delta;
if (0)
VG_(printf)("tid %d: stack_highest=0x%08lx ip=0x%08lx "
"sp=0x%08lx fp=0x%08lx\n",
tid, stack_highest_word, ip, sp, fp);
return VG_(get_StackTrace_wrk)(tid, ips, n_ips,
sps, fps,
ip, sp, fp, lr, sp,
stack_highest_word);
}
static void printIpDesc(UInt n, Addr ip)
{
#define BUF_LEN 4096
static UChar buf[BUF_LEN];
VG_(describe_IP)(ip, buf, BUF_LEN);
if (VG_(clo_xml)) {
VG_(message)(Vg_UserMsg, " %s", buf);
} else {
VG_(message)(Vg_UserMsg, " %s %s", ( n == 0 ? "at" : "by" ), buf);
}
}
/* Print a StackTrace. */
void VG_(pp_StackTrace) ( StackTrace ips, UInt n_ips )
{
vg_assert( n_ips > 0 );
if (VG_(clo_xml))
VG_(message)(Vg_UserMsg, " <stack>");
VG_(apply_StackTrace)( printIpDesc, ips, n_ips );
if (VG_(clo_xml))
VG_(message)(Vg_UserMsg, " </stack>");
}
/* Get and immediately print a StackTrace. */
void VG_(get_and_pp_StackTrace) ( ThreadId tid, UInt n_ips )
{
Addr ips[n_ips];
UInt n_ips_obtained
= VG_(get_StackTrace)(tid, ips, n_ips,
NULL/*array to dump SP values in*/,
NULL/*array to dump FP values in*/,
0/*first_ip_delta*/);
VG_(pp_StackTrace)(ips, n_ips_obtained);
}
void VG_(apply_StackTrace)( void(*action)(UInt n, Addr ip),
StackTrace ips, UInt n_ips )
{
#define MYBUF_LEN 50 // only needs to be long enough for
// the names specially tested for
Bool main_done = False;
Char mybuf[MYBUF_LEN]; // ok to stack allocate mybuf[] -- it's tiny
Int i = 0;
vg_assert(n_ips > 0);
do {
Addr ip = ips[i];
if (i > 0)
ip -= VG_MIN_INSTR_SZB; // point to calling line
// Stop after the first appearance of "main" or one of the other names
// (the appearance of which is a pretty good sign that we've gone past
// main without seeing it, for whatever reason)
if ( ! VG_(clo_show_below_main)) {
VG_(get_fnname_nodemangle)( ip, mybuf, MYBUF_LEN );
mybuf[MYBUF_LEN-1] = 0; // paranoia
if ( VG_STREQ("main", mybuf)
# if defined(VGO_linux)
|| VG_STREQ("__libc_start_main", mybuf) // glibc glibness
|| VG_STREQ("generic_start_main", mybuf) // Yellow Dog doggedness
# endif
)
main_done = True;
}
// Act on the ip
action(i, ip);
i++;
} while (i < n_ips && ips[i] != 0 && !main_done);
#undef MYBUF_LEN
}
/*--------------------------------------------------------------------*/
/*--- end ---*/
/*--------------------------------------------------------------------*/
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