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PageAccessControl Class Reference

Using the underlying. More...

Collaboration diagram for PageAccessControl:

Public Types

typedef std::vector< Entry > protected_t
 the list of protected pages More...
 
typedef protected_t::const_iterator const_iterator
 

Public Member Functions

 PageAccessControl (size_t reservedSize=65535)
 
 PageAccessControl (procmaps &pmaps, size_t reservedSize=65535)
 
template<typename T >
bool protectPage (T *addr, int prot)
 protect the page containing addr, record the amount of memory we protected NOTE To avoid SEGV, if PROT_WRITE is requested the remainder of the page containing the object at addr will be leaked with malloc before being write-locked More...
 
template<typename T >
bool forbidPage (const T *addr)
 forbid access to the page containing addr, setting its prot to PROT_NONE More...
 
bool forbidPage (const void *addr, size_t objSize)
 forbid access to the page containing addr, setting its prot to PROT_NONE More...
 
bool forbidPage (const void *addr)
 FIXME this will not work well for objects spanning across pages. More...
 
bool protectPage (const void *addr, size_t objSize, int prot)
 void* version of protectPage. Used to implement all others More...
 
bool restorePageProt (const void *addr)
 
void sort ()
 
const protected_t & protectedPtrs () const
 
const_iterator beginProtectedPtrs () const
 
const_iterator endProtectedPtrs () const
 
void reset ()
 
bool accessed (const void *address) const
 was the page containing address accessed? More...
 

Private Attributes

procmaps m_pmaps
 the content of /proc/self/maps More...
 
protected_t m_protected
 
bool m_protectedIsSorted
 

Detailed Description

Using the underlying.

access to page containing address

Member Typedef Documentation

◆ const_iterator

typedef protected_t::const_iterator PageAccessControl::const_iterator

Definition at line 92 of file PageAccessControl.h.

◆ protected_t

typedef std::vector<Entry> PageAccessControl::protected_t

the list of protected pages

Definition at line 91 of file PageAccessControl.h.

Constructor & Destructor Documentation

◆ PageAccessControl() [1/2]

PageAccessControl::PageAccessControl ( size_t  reservedSize = 65535)
inline

Definition at line 29 of file PageAccessControl.h.

29  :
30  m_pmaps(),
31  m_protectedIsSorted(false)
32  {
33  //we must reserve enough elements, or we risk vector allocating in a protected page during handle()...
34  m_protected.reserve(reservedSize);
35  }

◆ PageAccessControl() [2/2]

PageAccessControl::PageAccessControl ( procmaps &  pmaps,
size_t  reservedSize = 65535 
)
inline

Definition at line 36 of file PageAccessControl.h.

36  :
37  m_pmaps(pmaps),
38  m_protectedIsSorted(false)
39  {
40  //we must reserve enough elements, or we risk vector allocating in a protected page during handle()...
41  m_protected.reserve(reservedSize);
42  }

Member Function Documentation

◆ accessed()

bool PageAccessControl::accessed ( const void *  address) const

was the page containing address accessed?

Definition at line 118 of file PageAccessControl.cxx.

118  {
119  bool acc(false);
120  //fixme: poor man implementation
121  Entry eaxx(address,0,0,0);
122  PageAccessControl::const_iterator ia(beginProtectedPtrs()),
123  ea(endProtectedPtrs());
124  while (!acc && ia != ea) {
125  // std::cout << address << "page addr " << eaxx.addr << " ia " << ia->addr << " res " << ia->restored << std::endl;
126  acc = (eaxx.addr == ia->addr && 0 != ia->restored);
127  ++ia;
128  }
129  return acc;
130 }

◆ beginProtectedPtrs()

const_iterator PageAccessControl::beginProtectedPtrs ( ) const
inline

Definition at line 94 of file PageAccessControl.h.

94 { return m_protected.begin(); }

◆ endProtectedPtrs()

const_iterator PageAccessControl::endProtectedPtrs ( ) const
inline

Definition at line 95 of file PageAccessControl.h.

95 { return m_protected.end(); }

◆ forbidPage() [1/3]

template<typename T >
bool PageAccessControl::forbidPage ( const T *  addr)
inline

forbid access to the page containing addr, setting its prot to PROT_NONE

Definition at line 55 of file PageAccessControl.h.

55  {
56  return forbidPage(addr, sizeof(T));
57  }

◆ forbidPage() [2/3]

bool PageAccessControl::forbidPage ( const void *  addr)
inline

FIXME this will not work well for objects spanning across pages.

Definition at line 65 of file PageAccessControl.h.

65  {
66  return protectPage(addr, 4, PROT_NONE);
67  }

◆ forbidPage() [3/3]

bool PageAccessControl::forbidPage ( const void *  addr,
size_t  objSize 
)
inline

forbid access to the page containing addr, setting its prot to PROT_NONE

Definition at line 60 of file PageAccessControl.h.

60  {
61  return protectPage(addr, objSize, PROT_NONE);
62  }

◆ protectedPtrs()

const protected_t& PageAccessControl::protectedPtrs ( ) const
inline

Definition at line 93 of file PageAccessControl.h.

93 { return m_protected; }

◆ protectPage() [1/2]

bool PageAccessControl::protectPage ( const void *  addr,
size_t  objSize,
int  prot 
)

void* version of protectPage. Used to implement all others

Definition at line 56 of file PageAccessControl.cxx.

56  {
57  int rc(-1);
58  const procmaps::Entry *e=m_pmaps.getEntry(addr,true);
59  //this is the length of the range we are going to protect
60  if (0 != e) {
61  const void *pageAddr = page_address(addr);
62  size_t lenProt = (size_t)addr - (size_t)(pageAddr) + objSize;
63  size_t nextProt = (size_t)addr + objSize;
64  size_t nextUnprot = (size_t)(next_page_address((void*)(nextProt-1)));
65  int pageProt(PROT_NONE);
66  if (e->readable) pageProt |= PROT_READ;
67  if (e->writable) pageProt |= PROT_WRITE;
68  if (e->executable) pageProt |= PROT_EXEC;
69  if (pageProt != prot) {
70  //fill up the space from nextProt to nextUnprot to avoid allocations
71  //in the locked pages, and SEGVs...
72 // void *leak(0);
73 // if (0 == (prot & PROT_WRITE)) {
74 // size_t lenLeak(nextUnprot-nextProt-1);
75 // leak=malloc(lenLeak);
76 // if ((size_t)leak<nextUnprot && (size_t)leak + lenLeak>=nextUnprot) {
77 // //we do not want to allocate our buffer memory past the current
78 // //page, so trim it down
79 // free(leak);
80 // lenLeak=nextUnprot - (size_t)leak -1;
81 // leak=malloc(lenLeak);
82 // }
83 // if (leak < pageAddr ||
84 // (size_t)leak >= nextUnprot) {
85 // //leak has been allocated into previous/next page
86 // //better get rid of it as it will likely
87 // //be locked by another protectPage
88 // free(leak);
89 // leak=0;
90 // } else {
91 // #ifdef DEBUG
92 // printf("PageAccessControl::protectPage DEBUG: fill up space from %p to 0x%x to avoid allocations in locked pages\n",
93 // leak, (int)leak+lenLeak);
94 // #endif
95 // }
96 // }
97 
98  void* pageAddr_nc ATLAS_THREAD_SAFE = const_cast<void*> (pageAddr);
99  if (0 == (rc = mprotect( pageAddr_nc,
100  lenProt,
101  prot))) {
102  m_protected.push_back(Entry(pageAddr,lenProt, pageProt, 0));
103  m_protectedIsSorted=false; //FIXME we should use a mapvector
104 #ifdef DEBUG
105  printf("PageAccessControl::protectPage DEBUG: set protection %i for page range %p - 0x%lx containing address range=%p - 0x%lx\n",
106  prot,
107  pageAddr,
108  (long unsigned int)(nextUnprot - 1),
109  addr,
110  (long unsigned int)(nextProt -1) );
111 #endif
112  }
113  } else rc=0;
114  } else printf("PageAccessControl::protectPage WARNING: no entry in procmap for addr=%p, page protection not restored \n",addr);
115  return (rc == 0);
116 }

◆ protectPage() [2/2]

template<typename T >
bool PageAccessControl::protectPage ( T *  addr,
int  prot 
)
inline

protect the page containing addr, record the amount of memory we protected NOTE To avoid SEGV, if PROT_WRITE is requested the remainder of the page containing the object at addr will be leaked with malloc before being write-locked

Definition at line 49 of file PageAccessControl.h.

49  {
50  return protectPage(addr, sizeof(T), prot);
51  }

◆ reset()

void PageAccessControl::reset ( )
inline

Definition at line 96 of file PageAccessControl.h.

96 { m_protected.clear(); }

◆ restorePageProt()

bool PageAccessControl::restorePageProt ( const void *  addr)

Definition at line 27 of file PageAccessControl.cxx.

27  {
28  int rc(-1);
29  sort();
30  Entry ea(addr,0,0,0);
31  protected_t::iterator entry=
32  std::lower_bound(m_protected.begin(), m_protected.end(), ea);
33  if (entry != m_protected.end() &&
34  entry->addr == ea.addr) {
35  //found it. Restore page prot
36  const void* pageAddr = page_address(entry->addr);
37  void* pageAddr_nc ATLAS_THREAD_SAFE = const_cast<void*> (pageAddr);
38  rc=mprotect( pageAddr_nc, entry->lenProt, entry->prot);
39  if (rc==0) {
40 #ifdef DEBUG
41  printf("PageAccessControl::restorePageProt DEBUG: restored protection %i for page %p containing address %p \n",
42  entry->prot,
43  page_address(entry->addr),
44  entry->addr);
45  printf(" FIXME NOT Freeing memory at %p \n", entry->leak );
46 #endif
47  // free(entry->leak);
48  entry->leak=0;
49  ++(entry->restored);
50  }
51  } else printf("WARNING no entry in procmap for addr=%p, page protection not restored \n",addr);
52  return (rc == 0);
53 }

◆ sort()

void PageAccessControl::sort ( )

Definition at line 20 of file PageAccessControl.cxx.

20  {
21  if (!m_protectedIsSorted) {
22  std::sort(m_protected.begin(), m_protected.end());
23  m_protectedIsSorted=true;
24  }
25 }

Member Data Documentation

◆ m_pmaps

procmaps PageAccessControl::m_pmaps
private

the content of /proc/self/maps

Definition at line 104 of file PageAccessControl.h.

◆ m_protected

protected_t PageAccessControl::m_protected
private

Definition at line 109 of file PageAccessControl.h.

◆ m_protectedIsSorted

bool PageAccessControl::m_protectedIsSorted
private

Definition at line 110 of file PageAccessControl.h.

The documentation for this class was generated from the following files:
xAOD::iterator
JetConstituentVector::iterator iterator
Definition: JetConstituentVector.cxx:68
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Definition: AsgElectronSelectorTool.cxx:37
PageAccessControl::m_protected
protected_t m_protected
Definition: PageAccessControl.h:109
PageAccessControl::forbidPage
bool forbidPage(const T *addr)
forbid access to the page containing addr, setting its prot to PROT_NONE
Definition: PageAccessControl.h:55
athena::next_page_address
void * next_page_address(void *addr)
Definition: page_access.cxx:17
PageAccessControl::m_protectedIsSorted
bool m_protectedIsSorted
Definition: PageAccessControl.h:110
PageAccessControl::const_iterator
protected_t::const_iterator const_iterator
Definition: PageAccessControl.h:92
PageAccessControl::sort
void sort()
Definition: PageAccessControl.cxx:20
PageAccessControl::m_pmaps
procmaps m_pmaps
the content of /proc/self/maps
Definition: PageAccessControl.h:104
athena::page_address
const void * page_address(const void *addr)
Definition: page_access.cxx:11
AthenaPoolTestRead.acc
acc
Definition: AthenaPoolTestRead.py:16
PageAccessControl::beginProtectedPtrs
const_iterator beginProtectedPtrs() const
Definition: PageAccessControl.h:94
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list entry
Definition: GetAllXsec.py:132
RTTAlgmain.address
address
Definition: RTTAlgmain.py:55
std::sort
void sort(typename std::reverse_iterator< DataModel_detail::iterator< DVL > > beg, typename std::reverse_iterator< DataModel_detail::iterator< DVL > > end, const Compare &comp)
Specialization of sort for DataVector/List.
Definition: DVL_algorithms.h:623
procmaps::Entry
Definition: procmaps.h:20
procmaps::getEntry
const Entry * getEntry(const void *address, bool tryReloadMaps=true)
main entry point: get info for the page range containing address by default tries to reload /proc/sel...
Definition: procmaps.cxx:59
ATLAS_THREAD_SAFE
#define ATLAS_THREAD_SAFE
Definition: checker_macros.h:211
PageAccessControl::endProtectedPtrs
const_iterator endProtectedPtrs() const
Definition: PageAccessControl.h:95
TSU::T
unsigned long long T
Definition: L1TopoDataTypes.h:35
python.trfValidateRootFile.rc
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Definition: trfValidateRootFile.py:355
PageAccessControl::protectPage
bool protectPage(T *addr, int prot)
protect the page containing addr, record the amount of memory we protected NOTE To avoid SEGV,...
Definition: PageAccessControl.h:49
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