gdb/target-memory.c

   1 /* Parts of target interface that deal with accessing memory and memory-like
   2    objects.
   3
   4    Copyright (C) 2006-2024 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "target.h"
  23 #include "memory-map.h"
  24 #include "inferior.h"
  25
  26 #include "gdbsupport/gdb_sys_time.h"
  27 #include <algorithm>
  28
  29 static bool
  30 compare_block_starting_address (const memory_write_request &a_req,
  31                                 const memory_write_request &b_req)
  32 {
  33   return a_req.begin < b_req.begin;
  34 }
  35
  36 /* Adds to RESULT all memory write requests from BLOCK that are
  37    in [BEGIN, END) range.
  38
  39    If any memory request is only partially in the specified range,
  40    that part of the memory request will be added.  */
  41
  42 static void
  43 claim_memory (const std::vector<memory_write_request> &blocks,
  44               std::vector<memory_write_request> *result,
  45               ULONGEST begin,
  46               ULONGEST end)
  47 {
  48   ULONGEST claimed_begin;
  49   ULONGEST claimed_end;
  50
  51   for (const memory_write_request &r : blocks)
  52     {
  53       /* If the request doesn't overlap [BEGIN, END), skip it.  We
  54          must handle END == 0 meaning the top of memory; we don't yet
  55          check for R->end == 0, which would also mean the top of
  56          memory, but there's an assertion in
  57          target_write_memory_blocks which checks for that.  */
  58
  59       if (begin >= r.end)
  60         continue;
  61       if (end != 0 && end <= r.begin)
  62         continue;
  63
  64       claimed_begin = std::max (begin, r.begin);
  65       if (end == 0)
  66         claimed_end = r.end;
  67       else
  68         claimed_end = std::min (end, r.end);
  69
  70       if (claimed_begin == r.begin && claimed_end == r.end)
  71         result->push_back (r);
  72       else
  73         {
  74           struct memory_write_request n = r;
  75
  76           n.begin = claimed_begin;
  77           n.end = claimed_end;
  78           n.data += claimed_begin - r.begin;
  79
  80           result->push_back (n);
  81         }
  82     }
  83 }
  84
  85 /* Given a vector of struct memory_write_request objects in BLOCKS,
  86    add memory requests for flash memory into FLASH_BLOCKS, and for
  87    regular memory to REGULAR_BLOCKS.  */
  88
  89 static void
  90 split_regular_and_flash_blocks (const std::vector<memory_write_request> &blocks,
  91                                 std::vector<memory_write_request> *regular_blocks,
  92                                 std::vector<memory_write_request> *flash_blocks)
  93 {
  94   struct mem_region *region;
  95   CORE_ADDR cur_address;
  96
  97   /* This implementation runs in O(length(regions)*length(blocks)) time.
  98      However, in most cases the number of blocks will be small, so this does
  99      not matter.
 100
 101      Note also that it's extremely unlikely that a memory write request
 102      will span more than one memory region, however for safety we handle
 103      such situations.  */
 104
 105   cur_address = 0;
 106   while (1)
 107     {
 108       std::vector<memory_write_request> *r;
 109
 110       region = lookup_mem_region (cur_address);
 111       r = region->attrib.mode == MEM_FLASH ? flash_blocks : regular_blocks;
 112       cur_address = region->hi;
 113       claim_memory (blocks, r, region->lo, region->hi);
 114
 115       if (cur_address == 0)
 116         break;
 117     }
 118 }
 119
 120 /* Given an ADDRESS, if BEGIN is non-NULL this function sets *BEGIN
 121    to the start of the flash block containing the address.  Similarly,
 122    if END is non-NULL *END will be set to the address one past the end
 123    of the block containing the address.  */
 124
 125 static void
 126 block_boundaries (CORE_ADDR address, CORE_ADDR *begin, CORE_ADDR *end)
 127 {
 128   struct mem_region *region;
 129   unsigned blocksize;
 130   CORE_ADDR offset_in_region;
 131
 132   region = lookup_mem_region (address);
 133   gdb_assert (region->attrib.mode == MEM_FLASH);
 134   blocksize = region->attrib.blocksize;
 135
 136   offset_in_region = address - region->lo;
 137
 138   if (begin)
 139     *begin = region->lo + offset_in_region / blocksize * blocksize;
 140   if (end)
 141     *end = region->lo + (offset_in_region + blocksize - 1) / blocksize * blocksize;
 142 }
 143
 144 /* Given the list of memory requests to be WRITTEN, this function
 145    returns write requests covering each group of flash blocks which must
 146    be erased.  */
 147
 148 static std::vector<memory_write_request>
 149 blocks_to_erase (const std::vector<memory_write_request> &written)
 150 {
 151   std::vector<memory_write_request> result;
 152
 153   for (const memory_write_request &request : written)
 154     {
 155       CORE_ADDR begin, end;
 156
 157       block_boundaries (request.begin, &begin, 0);
 158       block_boundaries (request.end - 1, 0, &end);
 159
 160       if (!result.empty () && result.back ().end >= begin)
 161         result.back ().end = end;
 162       else
 163         result.emplace_back (begin, end);
 164     }
 165
 166   return result;
 167 }
 168
 169 /* Given ERASED_BLOCKS, a list of blocks that will be erased with
 170    flash erase commands, and WRITTEN_BLOCKS, the list of memory
 171    addresses that will be written, compute the set of memory addresses
 172    that will be erased but not rewritten (e.g. padding within a block
 173    which is only partially filled by "load").  */
 174
 175 static std::vector<memory_write_request>
 176 compute_garbled_blocks (const std::vector<memory_write_request> &erased_blocks,
 177                         const std::vector<memory_write_request> &written_blocks)
 178 {
 179   std::vector<memory_write_request> result;
 180
 181   unsigned j;
 182   unsigned je = written_blocks.size ();
 183
 184   /* Look at each erased memory_write_request in turn, and
 185      see what part of it is subsequently written to.
 186
 187      This implementation is O(length(erased) * length(written)).  If
 188      the lists are sorted at this point it could be rewritten more
 189      efficiently, but the complexity is not generally worthwhile.  */
 190
 191   for (const memory_write_request &erased_iter : erased_blocks)
 192     {
 193       /* Make a deep copy -- it will be modified inside the loop, but
 194          we don't want to modify original vector.  */
 195       struct memory_write_request erased = erased_iter;
 196
 197       for (j = 0; j != je;)
 198         {
 199           const memory_write_request *written = &written_blocks[j];
 200
 201           /* Now try various cases.  */
 202
 203           /* If WRITTEN is fully to the left of ERASED, check the next
 204              written memory_write_request.  */
 205           if (written->end <= erased.begin)
 206             {
 207               ++j;
 208               continue;
 209             }
 210
 211           /* If WRITTEN is fully to the right of ERASED, then ERASED
 212              is not written at all.  WRITTEN might affect other
 213              blocks.  */
 214           if (written->begin >= erased.end)
 215             {
 216               result.push_back (erased);
 217               goto next_erased;
 218             }
 219
 220           /* If all of ERASED is completely written, we can move on to
 221              the next erased region.  */
 222           if (written->begin <= erased.begin
 223               && written->end >= erased.end)
 224             {
 225               goto next_erased;
 226             }
 227
 228           /* If there is an unwritten part at the beginning of ERASED,
 229              then we should record that part and try this inner loop
 230              again for the remainder.  */
 231           if (written->begin > erased.begin)
 232             {
 233               result.emplace_back (erased.begin, written->begin);
 234               erased.begin = written->begin;
 235               continue;
 236             }
 237
 238           /* If there is an unwritten part at the end of ERASED, we
 239              forget about the part that was written to and wait to see
 240              if the next write request writes more of ERASED.  We can't
 241              push it yet.  */
 242           if (written->end < erased.end)
 243             {
 244               erased.begin = written->end;
 245               ++j;
 246               continue;
 247             }
 248         }
 249
 250       /* If we ran out of write requests without doing anything about
 251          ERASED, then that means it's really erased.  */
 252       result.push_back (erased);
 253
 254     next_erased:
 255       ;
 256     }
 257
 258   return result;
 259 }
 260
 261 int
 262 target_write_memory_blocks (const std::vector<memory_write_request> &requests,
 263                             enum flash_preserve_mode preserve_flash_p,
 264                             void (*progress_cb) (ULONGEST, void *))
 265 {
 266   std::vector<memory_write_request> blocks = requests;
 267   std::vector<memory_write_request> regular;
 268   std::vector<memory_write_request> flash;
 269   std::vector<memory_write_request> erased, garbled;
 270
 271   /* END == 0 would represent wraparound: a write to the very last
 272      byte of the address space.  This file was not written with that
 273      possibility in mind.  This is fixable, but a lot of work for a
 274      rare problem; so for now, fail noisily here instead of obscurely
 275      later.  */
 276   for (const memory_write_request &iter : requests)
 277     gdb_assert (iter.end != 0);
 278
 279   /* Sort the blocks by their start address.  */
 280   std::sort (blocks.begin (), blocks.end (), compare_block_starting_address);
 281
 282   /* Split blocks into list of regular memory blocks,
 283      and list of flash memory blocks.  */
 284   split_regular_and_flash_blocks (blocks, &regular, &flash);
 285
 286   /* If a variable is added to forbid flash write, even during "load",
 287      it should be checked here.  Similarly, if this function is used
 288      for other situations besides "load" in which writing to flash
 289      is undesirable, that should be checked here.  */
 290
 291   /* Find flash blocks to erase.  */
 292   erased = blocks_to_erase (flash);
 293
 294   /* Find what flash regions will be erased, and not overwritten; then
 295      either preserve or discard the old contents.  */
 296   garbled = compute_garbled_blocks (erased, flash);
 297
 298   std::vector<gdb::unique_xmalloc_ptr<gdb_byte>> mem_holders;
 299   if (!garbled.empty ())
 300     {
 301       if (preserve_flash_p == flash_preserve)
 302         {
 303           /* Read in regions that must be preserved and add them to
 304              the list of blocks we read.  */
 305           for (memory_write_request &iter : garbled)
 306             {
 307               gdb_assert (iter.data == NULL);
 308               gdb::unique_xmalloc_ptr<gdb_byte> holder
 309                 ((gdb_byte *) xmalloc (iter.end - iter.begin));
 310               iter.data = holder.get ();
 311               mem_holders.push_back (std::move (holder));
 312               int err = target_read_memory (iter.begin, iter.data,
 313                                             iter.end - iter.begin);
 314               if (err != 0)
 315                 return err;
 316
 317               flash.push_back (iter);
 318             }
 319
 320           std::sort (flash.begin (), flash.end (),
 321                      compare_block_starting_address);
 322         }
 323     }
 324
 325   /* We could coalesce adjacent memory blocks here, to reduce the
 326      number of write requests for small sections.  However, we would
 327      have to reallocate and copy the data pointers, which could be
 328      large; large sections are more common in loadable objects than
 329      large numbers of small sections (although the reverse can be true
 330      in object files).  So, we issue at least one write request per
 331      passed struct memory_write_request.  The remote stub will still
 332      have the opportunity to batch flash requests.  */
 333
 334   /* Write regular blocks.  */
 335   for (const memory_write_request &iter : regular)
 336     {
 337       LONGEST len;
 338
 339       len = target_write_with_progress (current_inferior ()->top_target (),
 340                                         TARGET_OBJECT_MEMORY, NULL,
 341                                         iter.data, iter.begin,
 342                                         iter.end - iter.begin,
 343                                         progress_cb, iter.baton);
 344       if (len < (LONGEST) (iter.end - iter.begin))
 345         {
 346           /* Call error?  */
 347           return -1;
 348         }
 349     }
 350
 351   if (!erased.empty ())
 352     {
 353       /* Erase all pages.  */
 354       for (const memory_write_request &iter : erased)
 355         target_flash_erase (iter.begin, iter.end - iter.begin);
 356
 357       /* Write flash data.  */
 358       for (const memory_write_request &iter : flash)
 359         {
 360           LONGEST len;
 361
 362           len = target_write_with_progress (current_inferior ()->top_target (),
 363                                             TARGET_OBJECT_FLASH, NULL,
 364                                             iter.data, iter.begin,
 365                                             iter.end - iter.begin,
 366                                             progress_cb, iter.baton);
 367           if (len < (LONGEST) (iter.end - iter.begin))
 368             error (_("Error writing data to flash"));
 369         }
 370
 371       target_flash_done ();
 372     }
 373
 374   return 0;
 375 }