Commit 7d992e4d authored by Peter Lieven's avatar Peter Lieven Committed by Kevin Wolf
Browse files

oslib-posix: add a configure switch to debug stack usage 



this adds a knob to track the maximum stack usage of stacks
created by qemu_alloc_stack.

Signed-off-by: default avatarPeter Lieven <pl@kamp.de>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 2f4aa232

configure

+19 −0
Original line number Diff line number Diff line
@@ -296,6 +296,7 @@ libiscsi="" 
libnfs=""

coroutine=""

coroutine_pool=""

debug_stack_usage="no"

seccomp=""

glusterfs=""

glusterfs_xlator_opt="no"
@@ -1004,6 +1005,8 @@ for opt do 
  ;;

  --enable-coroutine-pool) coroutine_pool="yes"

  ;;

  --enable-debug-stack-usage) debug_stack_usage="yes"

  ;;

  --disable-docs) docs="no"

  ;;

  --enable-docs) docs="yes"
@@ -4331,6 +4334,17 @@ if test "$coroutine" = "gthread" -a "$coroutine_pool" = "yes"; then 
  error_exit "'gthread' coroutine backend does not support pool (use --disable-coroutine-pool)"

fi



if test "$debug_stack_usage" = "yes"; then

  if test "$cpu" = "ia64" -o "$cpu" = "hppa"; then

    error_exit "stack usage debugging is not supported for $cpu"

  fi

  if test "$coroutine_pool" = "yes"; then

    echo "WARN: disabling coroutine pool for stack usage debugging"

    coroutine_pool=no

  fi

fi





##########################################

# check if we have open_by_handle_at
@@ -4916,6 +4930,7 @@ echo "QGA MSI support $guest_agent_msi" 
echo "seccomp support   $seccomp"

echo "coroutine backend $coroutine"

echo "coroutine pool    $coroutine_pool"

echo "debug stack usage $debug_stack_usage"

echo "GlusterFS support $glusterfs"

echo "Archipelago support $archipelago"

echo "gcov              $gcov_tool"
@@ -5384,6 +5399,10 @@ else 
  echo "CONFIG_COROUTINE_POOL=0" >> $config_host_mak

fi



if test "$debug_stack_usage" = "yes" ; then

  echo "CONFIG_DEBUG_STACK_USAGE=y" >> $config_host_mak

fi



if test "$open_by_handle_at" = "yes" ; then

  echo "CONFIG_OPEN_BY_HANDLE=y" >> $config_host_mak

fi

util/oslib-posix.c

+35 −0
Original line number Diff line number Diff line
@@ -50,6 +50,10 @@ 


#include "qemu/mmap-alloc.h"



#ifdef CONFIG_DEBUG_STACK_USAGE

#include "qemu/error-report.h"

#endif



int qemu_get_thread_id(void)

{

#if defined(__linux__)
@@ -503,6 +507,9 @@ pid_t qemu_fork(Error **errp) 
void *qemu_alloc_stack(size_t *sz)

{

    void *ptr, *guardpage;

#ifdef CONFIG_DEBUG_STACK_USAGE

    void *ptr2;

#endif

    size_t pagesz = getpagesize();

#ifdef _SC_THREAD_STACK_MIN

    /* avoid stacks smaller than _SC_THREAD_STACK_MIN */
@@ -534,10 +541,38 @@ void *qemu_alloc_stack(size_t *sz) 
        abort();

    }



#ifdef CONFIG_DEBUG_STACK_USAGE

    for (ptr2 = ptr + pagesz; ptr2 < ptr + *sz; ptr2 += sizeof(uint32_t)) {

        *(uint32_t *)ptr2 = 0xdeadbeaf;

    }

#endif



    return ptr;

}



#ifdef CONFIG_DEBUG_STACK_USAGE

static __thread unsigned int max_stack_usage;

#endif



void qemu_free_stack(void *stack, size_t sz)

{

#ifdef CONFIG_DEBUG_STACK_USAGE

    unsigned int usage;

    void *ptr;



    for (ptr = stack + getpagesize(); ptr < stack + sz;

         ptr += sizeof(uint32_t)) {

        if (*(uint32_t *)ptr != 0xdeadbeaf) {

            break;

        }

    }

    usage = sz - (uintptr_t) (ptr - stack);

    if (usage > max_stack_usage) {

        error_report("thread %d max stack usage increased from %u to %u",

                     qemu_get_thread_id(), max_stack_usage, usage);

        max_stack_usage = usage;

    }

#endif



    munmap(stack, sz);

}