diff options
Diffstat (limited to 'gdb/auxv.c')
| -rw-r--r-- | gdb/auxv.c | 73 |
1 files changed, 40 insertions, 33 deletions
@@ -34,8 +34,8 @@ #include <fcntl.h> -/* This function handles access via /proc/PID/auxv, which is a common method - for native targets. */ +/* This function handles access via /proc/PID/auxv, which is a common + method for native targets. */ static LONGEST procfs_xfer_auxv (gdb_byte *readbuf, @@ -90,35 +90,39 @@ ld_so_xfer_auxv (gdb_byte *readbuf, if (MSYMBOL_SIZE (msym) != ptr_size) return -1; - /* POINTER_ADDRESS is a location where the `_dl_auxv' variable resides. - DATA_ADDRESS is the inferior value present in `_dl_auxv', therefore the - real inferior AUXV address. */ + /* POINTER_ADDRESS is a location where the `_dl_auxv' variable + resides. DATA_ADDRESS is the inferior value present in + `_dl_auxv', therefore the real inferior AUXV address. */ pointer_address = SYMBOL_VALUE_ADDRESS (msym); /* The location of the _dl_auxv symbol may no longer be correct if - ld.so runs at a different address than the one present in the file. - This is very common case - for unprelinked ld.so or with a PIE executable. - PIE executable forces random address even for libraries already being - prelinked to some address. PIE executables themselves are never prelinked - even on prelinked systems. Prelinking of a PIE executable would block - their purpose of randomizing load of everything including the executable. - - If the memory read fails, return -1 to fallback on another mechanism for - retrieving the AUXV. - - In most cases of a PIE running under valgrind there is no way to find - out the base addresses of any of ld.so, executable or AUXV as everything - is randomized and /proc information is not relevant for the virtual - executable running under valgrind. We think that we might need a valgrind - extension to make it work. This is PR 11440. */ + ld.so runs at a different address than the one present in the + file. This is very common case - for unprelinked ld.so or with a + PIE executable. PIE executable forces random address even for + libraries already being prelinked to some address. PIE + executables themselves are never prelinked even on prelinked + systems. Prelinking of a PIE executable would block their + purpose of randomizing load of everything including the + executable. + + If the memory read fails, return -1 to fallback on another + mechanism for retrieving the AUXV. + + In most cases of a PIE running under valgrind there is no way to + find out the base addresses of any of ld.so, executable or AUXV + as everything is randomized and /proc information is not relevant + for the virtual executable running under valgrind. We think that + we might need a valgrind extension to make it work. This is PR + 11440. */ if (target_read_memory (pointer_address, ptr_buf, ptr_size) != 0) return -1; data_address = extract_typed_address (ptr_buf, ptr_type); - /* Possibly still not initialized such as during an inferior startup. */ + /* Possibly still not initialized such as during an inferior + startup. */ if (data_address == 0) return -1; @@ -132,8 +136,8 @@ ld_so_xfer_auxv (gdb_byte *readbuf, return -1; } - /* Stop if trying to read past the existing AUXV block. The final AT_NULL - was already returned before. */ + /* Stop if trying to read past the existing AUXV block. The final + AT_NULL was already returned before. */ if (offset >= auxv_pair_size) { @@ -154,9 +158,10 @@ ld_so_xfer_auxv (gdb_byte *readbuf, if (block > len) block = len; - /* Reading sizes smaller than AUXV_PAIR_SIZE is not supported. Tails - unaligned to AUXV_PAIR_SIZE will not be read during a call (they - should be completed during next read with new/extended buffer). */ + /* Reading sizes smaller than AUXV_PAIR_SIZE is not supported. + Tails unaligned to AUXV_PAIR_SIZE will not be read during a + call (they should be completed during next read with + new/extended buffer). */ block &= -auxv_pair_size; if (block == 0) @@ -174,8 +179,9 @@ ld_so_xfer_auxv (gdb_byte *readbuf, data_address += block; len -= block; - /* Check terminal AT_NULL. This function is being called indefinitely - being extended its READBUF until it returns EOF (0). */ + /* Check terminal AT_NULL. This function is being called + indefinitely being extended its READBUF until it returns EOF + (0). */ while (block >= auxv_pair_size) { @@ -207,10 +213,11 @@ memory_xfer_auxv (struct target_ops *ops, gdb_assert (object == TARGET_OBJECT_AUXV); gdb_assert (readbuf || writebuf); - /* ld_so_xfer_auxv is the only function safe for virtual executables being - executed by valgrind's memcheck. Using ld_so_xfer_auxv during inferior - startup is problematic, because ld.so symbol tables have not yet been - relocated. So GDB uses this function only when attaching to a process. + /* ld_so_xfer_auxv is the only function safe for virtual + executables being executed by valgrind's memcheck. Using + ld_so_xfer_auxv during inferior startup is problematic, because + ld.so symbol tables have not yet been relocated. So GDB uses + this function only when attaching to a process. */ if (current_inferior ()->attach_flag != 0) @@ -308,7 +315,7 @@ target_auxv_search (struct target_ops *ops, CORE_ADDR match, CORE_ADDR *valp) } -/* Print the contents of the target's AUXV on the specified file. */ +/* Print the contents of the target's AUXV on the specified file. */ int fprint_target_auxv (struct ui_file *file, struct target_ops *ops) { |