1 //===-- BreakpointSite.h ----------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLDB_BREAKPOINT_BREAKPOINTSITE_H
10 #define LLDB_BREAKPOINT_BREAKPOINTSITE_H
11 
12 #include <list>
13 #include <mutex>
14 
15 
16 #include "lldb/Breakpoint/BreakpointLocationCollection.h"
17 #include "lldb/Breakpoint/StoppointSite.h"
18 #include "lldb/Utility/LLDBAssert.h"
19 #include "lldb/Utility/UserID.h"
20 #include "lldb/lldb-forward.h"
21 
22 namespace lldb_private {
23 
24 /// \class BreakpointSite BreakpointSite.h "lldb/Breakpoint/BreakpointSite.h"
25 /// Class that manages the actual breakpoint that will be inserted into the
26 /// running program.
27 ///
28 /// The BreakpointSite class handles the physical breakpoint that is actually
29 /// inserted in the target program.  As such, it is also the one that  gets
30 /// hit, when the program stops. It keeps a list of all BreakpointLocations
31 /// that share this physical site. When the breakpoint is hit, all the
32 /// locations are informed by the breakpoint site. Breakpoint sites are owned
33 /// by the process.
34 
35 class BreakpointSite : public std::enable_shared_from_this<BreakpointSite>,
36                        public StoppointSite {
37 public:
38   enum Type {
39     eSoftware, // Breakpoint opcode has been written to memory and
40                // m_saved_opcode
41                // and m_trap_opcode contain the saved and written opcode.
42     eHardware, // Breakpoint site is set as a hardware breakpoint
43     eExternal  // Breakpoint site is managed by an external debug nub or
44                // debug interface where memory reads transparently will not
45                // display any breakpoint opcodes.
46   };
47 
48   ~BreakpointSite() override;
49 
50   // This section manages the breakpoint traps
51 
52   /// Returns the Opcode Bytes for this breakpoint
53   uint8_t *GetTrapOpcodeBytes();
54 
55   /// Returns the Opcode Bytes for this breakpoint - const version
56   const uint8_t *GetTrapOpcodeBytes() const;
57 
58   /// Get the size of the trap opcode for this address
59   size_t GetTrapOpcodeMaxByteSize() const;
60 
61   /// Sets the trap opcode
62   bool SetTrapOpcode(const uint8_t *trap_opcode, uint32_t trap_opcode_size);
63 
64   /// Gets the original instruction bytes that were overwritten by the trap
65   uint8_t *GetSavedOpcodeBytes();
66 
67   /// Gets the original instruction bytes that were overwritten by the trap
68   /// const version
69   const uint8_t *GetSavedOpcodeBytes() const;
70 
71   /// Says whether \a addr and size \a size intersects with the address \a
72   /// intersect_addr
73   bool IntersectsRange(lldb::addr_t addr, size_t size,
74                        lldb::addr_t *intersect_addr, size_t *intersect_size,
75                        size_t *opcode_offset) const;
76 
77   /// Tells whether the current breakpoint site is enabled or not
78   ///
79   /// This is a low-level enable bit for the breakpoint sites.  If a
80   /// breakpoint site has no enabled owners, it should just get removed.  This
81   /// enable/disable is for the low-level target code to enable and disable
82   /// breakpoint sites when single stepping, etc.
83   bool IsEnabled() const;
84 
85   /// Sets whether the current breakpoint site is enabled or not
86   ///
87   /// \param[in] enabled
88   ///    \b true if the breakpoint is enabled, \b false otherwise.
89   void SetEnabled(bool enabled);
90 
91   /// Enquires of the breakpoint locations that produced this breakpoint site
92   /// whether we should stop at this location.
93   ///
94   /// \param[in] context
95   ///    This contains the information about this stop.
96   ///
97   /// \return
98   ///    \b true if we should stop, \b false otherwise.
99   bool ShouldStop(StoppointCallbackContext *context) override;
100 
101   /// Standard Dump method
102   void Dump(Stream *s) const override;
103 
104   /// The "Owners" are the breakpoint locations that share this breakpoint
105   /// site. The method adds the \a owner to this breakpoint site's owner list.
106   ///
107   /// \param[in] owner
108   ///    \a owner is the Breakpoint Location to add.
109   void AddOwner(const lldb::BreakpointLocationSP &owner);
110 
111   /// This method returns the number of breakpoint locations currently located
112   /// at this breakpoint site.
113   ///
114   /// \return
115   ///    The number of owners.
116   size_t GetNumberOfOwners();
117 
118   /// This method returns the breakpoint location at index \a index located at
119   /// this breakpoint site.  The owners are listed ordinally from 0 to
120   /// GetNumberOfOwners() - 1 so you can use this method to iterate over the
121   /// owners
122   ///
123   /// \param[in] idx
124   ///     The index in the list of owners for which you wish the owner location.
125   ///
126   /// \return
127   ///    A shared pointer to the breakpoint location at that index.
128   lldb::BreakpointLocationSP GetOwnerAtIndex(size_t idx);
129 
130   /// This method copies the breakpoint site's owners into a new collection.
131   /// It does this while the owners mutex is locked.
132   ///
133   /// \param[out] out_collection
134   ///    The BreakpointLocationCollection into which to put the owners
135   ///    of this breakpoint site.
136   ///
137   /// \return
138   ///    The number of elements copied into out_collection.
139   size_t CopyOwnersList(BreakpointLocationCollection &out_collection);
140 
141   /// Check whether the owners of this breakpoint site have any thread
142   /// specifiers, and if yes, is \a thread contained in any of these
143   /// specifiers.
144   ///
145   /// \param[in] thread
146   ///     The thread against which to test.
147   ///
148   /// return
149   ///     \b true if the collection contains at least one location that
150   ///     would be valid for this thread, false otherwise.
151   bool ValidForThisThread(Thread &thread);
152 
153   /// Print a description of this breakpoint site to the stream \a s.
154   /// GetDescription tells you about the breakpoint site's owners. Use
155   /// BreakpointSite::Dump(Stream *) to get information about the breakpoint
156   /// site itself.
157   ///
158   /// \param[in] s
159   ///     The stream to which to print the description.
160   ///
161   /// \param[in] level
162   ///     The description level that indicates the detail level to
163   ///     provide.
164   ///
165   /// \see lldb::DescriptionLevel
166   void GetDescription(Stream *s, lldb::DescriptionLevel level);
167 
168   /// Tell whether a breakpoint has a location at this site.
169   ///
170   /// \param[in] bp_id
171   ///     The breakpoint id to query.
172   ///
173   /// \result
174   ///     \b true if bp_id has a location that is at this site,
175   ///     \b false otherwise.
176   bool IsBreakpointAtThisSite(lldb::break_id_t bp_id);
177 
178   /// Tell whether ALL the breakpoints in the location collection are
179   /// internal.
180   ///
181   /// \result
182   ///     \b true if all breakpoint locations are owned by internal breakpoints,
183   ///     \b false otherwise.
184   bool IsInternal() const;
185 
186   bool IsHardware() const override {
187     lldbassert(BreakpointSite::Type::eHardware == GetType() ||
188                !HardwareRequired());
189     return BreakpointSite::Type::eHardware == GetType();
190   }
191 
192   BreakpointSite::Type GetType() const { return m_type; }
193 
194   void SetType(BreakpointSite::Type type) { m_type = type; }
195 
196 private:
197   friend class Process;
198   friend class BreakpointLocation;
199   // The StopInfoBreakpoint knows when it is processing a hit for a thread for
200   // a site, so let it be the one to manage setting the location hit count once
201   // and only once.
202   friend class StopInfoBreakpoint;
203 
204   void BumpHitCounts();
205 
206   /// The method removes the owner at \a break_loc_id from this breakpoint
207   /// list.
208   size_t RemoveOwner(lldb::break_id_t break_id, lldb::break_id_t break_loc_id);
209 
210   BreakpointSite::Type m_type; ///< The type of this breakpoint site.
211   uint8_t m_saved_opcode[8]; ///< The saved opcode bytes if this breakpoint site
212                              ///uses trap opcodes.
213   uint8_t m_trap_opcode[8];  ///< The opcode that was used to create the
214                              ///breakpoint if it is a software breakpoint site.
215   bool
216       m_enabled; ///< Boolean indicating if this breakpoint site enabled or not.
217 
218   // Consider adding an optimization where if there is only one owner, we don't
219   // store a list.  The usual case will be only one owner...
220   BreakpointLocationCollection m_owners; ///< This has the BreakpointLocations
221                                          ///that share this breakpoint site.
222   std::recursive_mutex
223       m_owners_mutex; ///< This mutex protects the owners collection.
224 
225   static lldb::break_id_t GetNextID();
226 
227   // Only the Process can create breakpoint sites in
228   // Process::CreateBreakpointSite (lldb::BreakpointLocationSP &, bool).
229   BreakpointSite(BreakpointSiteList *list,
230                  const lldb::BreakpointLocationSP &owner, lldb::addr_t m_addr,
231                  bool use_hardware);
232 
233   BreakpointSite(const BreakpointSite &) = delete;
234   const BreakpointSite &operator=(const BreakpointSite &) = delete;
235 };
236 
237 } // namespace lldb_private
238 
239 #endif // LLDB_BREAKPOINT_BREAKPOINTSITE_H
240