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* solib-svr4.c (read_program_header): New function.

Browse Source 
(scan_dyntag_auxv): New function.
	(elf_locate_base): Use it if scan_dyntag fails.
	(find_program_interpreter): New function.
	(enable_break): Use it instead of .interp section.
This commit is contained in:
Ulrich Weigand 2008-08-26 17:33:51 +00:00
parent f1838a9841
commit 97ec2c2fb8
2 changed files with 205 additions and 16 deletions
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8
gdb/ChangeLog
View File

@ -1,3 +1,11 @@
2008-08-26 Ulrich Weigand <uweigand@de.ibm.com>
* solib-svr4.c (read_program_header): New function.
(scan_dyntag_auxv): New function.
(elf_locate_base): Use it if scan_dyntag fails.
(find_program_interpreter): New function.
(enable_break): Use it instead of .interp section.
2008-08-26 Ulrich Weigand <uweigand@de.ibm.com>
* remote.h (remote_filename_p, remote_bfd_open): Add prototypes.

213
gdb/solib-svr4.c
View File

@ -374,6 +374,137 @@ bfd_lookup_symbol (bfd *abfd, char *symname)
return symaddr;
}
/* Read program header TYPE from inferior memory. The header is found
by scanning the OS auxillary vector.
Return a pointer to allocated memory holding the program header contents,
or NULL on failure. If sucessful, and unless P_SECT_SIZE is NULL, the
size of those contents is returned to P_SECT_SIZE. Likewise, the target
architecture size (32-bit or 64-bit) is returned to P_ARCH_SIZE. */
static gdb_byte *
read_program_header (int type, int *p_sect_size, int *p_arch_size)
{
CORE_ADDR at_phdr, at_phent, at_phnum;
int arch_size, sect_size;
CORE_ADDR sect_addr;
gdb_byte *buf;
/* Get required auxv elements from target. */
if (target_auxv_search (&current_target, AT_PHDR, &at_phdr) <= 0)
return 0;
if (target_auxv_search (&current_target, AT_PHENT, &at_phent) <= 0)
return 0;
if (target_auxv_search (&current_target, AT_PHNUM, &at_phnum) <= 0)
return 0;
if (!at_phdr || !at_phnum)
return 0;
/* Determine ELF architecture type. */
if (at_phent == sizeof (Elf32_External_Phdr))
arch_size = 32;
else if (at_phent == sizeof (Elf64_External_Phdr))
arch_size = 64;
else
return 0;
/* Find .dynamic section via the PT_DYNAMIC PHDR. */
if (arch_size == 32)
{
Elf32_External_Phdr phdr;
int i;
/* Search for requested PHDR. */
for (i = 0; i < at_phnum; i++)
{
if (target_read_memory (at_phdr + i * sizeof (phdr),
(gdb_byte *)&phdr, sizeof (phdr)))
return 0;
if (extract_unsigned_integer ((gdb_byte *)phdr.p_type, 4) == type)
break;
}
if (i == at_phnum)
return 0;
/* Retrieve address and size. */
sect_addr = extract_unsigned_integer ((gdb_byte *)phdr.p_vaddr, 4);
sect_size = extract_unsigned_integer ((gdb_byte *)phdr.p_memsz, 4);
}
else
{
Elf64_External_Phdr phdr;
int i;
/* Search for requested PHDR. */
for (i = 0; i < at_phnum; i++)
{
if (target_read_memory (at_phdr + i * sizeof (phdr),
(gdb_byte *)&phdr, sizeof (phdr)))
return 0;
if (extract_unsigned_integer ((gdb_byte *)phdr.p_type, 4) == type)
break;
}
if (i == at_phnum)
return 0;
/* Retrieve address and size. */
sect_addr = extract_unsigned_integer ((gdb_byte *)phdr.p_vaddr, 8);
sect_size = extract_unsigned_integer ((gdb_byte *)phdr.p_memsz, 8);
}
/* Read in requested program header. */
buf = xmalloc (sect_size);
if (target_read_memory (sect_addr, buf, sect_size))
{
xfree (buf);
return NULL;
}
if (p_arch_size)
*p_arch_size = arch_size;
if (p_sect_size)
*p_sect_size = sect_size;
return buf;
}
/* Return program interpreter string. */
static gdb_byte *
find_program_interpreter (void)
{
gdb_byte *buf = NULL;
/* If we have an exec_bfd, use its section table. */
if (exec_bfd
&& bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour)
{
struct bfd_section *interp_sect;
interp_sect = bfd_get_section_by_name (exec_bfd, ".interp");
if (interp_sect != NULL)
{
CORE_ADDR sect_addr = bfd_section_vma (exec_bfd, interp_sect);
int sect_size = bfd_section_size (exec_bfd, interp_sect);
buf = xmalloc (sect_size);
bfd_get_section_contents (exec_bfd, interp_sect, buf, 0, sect_size);
}
}
/* If we didn't find it, use the target auxillary vector. */
if (!buf)
buf = read_program_header (PT_INTERP, NULL, NULL);
return buf;
}
/* Scan for DYNTAG in .dynamic section of ABFD. If DYNTAG is found 1 is
returned and the corresponding PTR is set. */
@ -451,6 +582,59 @@ scan_dyntag (int dyntag, bfd *abfd, CORE_ADDR *ptr)
return 0;
}
/* Scan for DYNTAG in .dynamic section of the target's main executable,
found by consulting the OS auxillary vector. If DYNTAG is found 1 is
returned and the corresponding PTR is set. */
static int
scan_dyntag_auxv (int dyntag, CORE_ADDR *ptr)
{
int sect_size, arch_size, step;
long dyn_tag;
CORE_ADDR dyn_ptr;
gdb_byte *bufend, *bufstart, *buf;
/* Read in .dynamic section. */
buf = bufstart = read_program_header (PT_DYNAMIC, &sect_size, &arch_size);
if (!buf)
return 0;
/* Iterate over BUF and scan for DYNTAG. If found, set PTR and return. */
step = (arch_size == 32) ? sizeof (Elf32_External_Dyn)
: sizeof (Elf64_External_Dyn);
for (bufend = buf + sect_size;
buf < bufend;
buf += step)
{
if (arch_size == 32)
{
Elf32_External_Dyn *dynp = (Elf32_External_Dyn *) buf;
dyn_tag = extract_unsigned_integer ((gdb_byte *) dynp->d_tag, 4);
dyn_ptr = extract_unsigned_integer ((gdb_byte *) dynp->d_un.d_ptr, 4);
}
else
{
Elf64_External_Dyn *dynp = (Elf64_External_Dyn *) buf;
dyn_tag = extract_unsigned_integer ((gdb_byte *) dynp->d_tag, 8);
dyn_ptr = extract_unsigned_integer ((gdb_byte *) dynp->d_un.d_ptr, 8);
}
if (dyn_tag == DT_NULL)
break;
if (dyn_tag == dyntag)
{
if (ptr)
*ptr = dyn_ptr;
xfree (bufstart);
return 1;
}
}
xfree (bufstart);
return 0;
}
/*
@ -485,7 +669,8 @@ elf_locate_base (void)
/* Look for DT_MIPS_RLD_MAP first. MIPS executables use this
instead of DT_DEBUG, although they sometimes contain an unused
DT_DEBUG. */
if (scan_dyntag (DT_MIPS_RLD_MAP, exec_bfd, &dyn_ptr))
if (scan_dyntag (DT_MIPS_RLD_MAP, exec_bfd, &dyn_ptr)
|| scan_dyntag_auxv (DT_MIPS_RLD_MAP, &dyn_ptr))
{
gdb_byte *pbuf;
int pbuf_size = TYPE_LENGTH (builtin_type_void_data_ptr);
@ -498,7 +683,8 @@ elf_locate_base (void)
}
/* Find DT_DEBUG. */
if (scan_dyntag (DT_DEBUG, exec_bfd, &dyn_ptr))
if (scan_dyntag (DT_DEBUG, exec_bfd, &dyn_ptr)
|| scan_dyntag_auxv (DT_DEBUG, &dyn_ptr))
return dyn_ptr;
/* This may be a static executable. Look for the symbol
@ -964,6 +1150,7 @@ enable_break (void)
struct minimal_symbol *msymbol;
char **bkpt_namep;
asection *interp_sect;
gdb_byte *interp_name;
CORE_ADDR sym_addr;
/* First, remove all the solib event breakpoints. Their addresses
@ -1026,13 +1213,11 @@ enable_break (void)
}
}
/* Find the .interp section; if not found, warn the user and drop
/* Find the program interpreter; if not found, warn the user and drop
into the old breakpoint at symbol code. */
interp_sect = bfd_get_section_by_name (exec_bfd, ".interp");
if (interp_sect)
interp_name = find_program_interpreter ();
if (interp_name)
{
unsigned int interp_sect_size;
char *buf;
CORE_ADDR load_addr = 0;
int load_addr_found = 0;
int loader_found_in_list = 0;
@ -1041,13 +1226,7 @@ enable_break (void)
struct target_ops *tmp_bfd_target;
volatile struct gdb_exception ex;
/* Read the contents of the .interp section into a local buffer;
the contents specify the dynamic linker this program uses. */
sym_addr = 0;
interp_sect_size = bfd_section_size (exec_bfd, interp_sect);
buf = alloca (interp_sect_size);
bfd_get_section_contents (exec_bfd, interp_sect,
buf, 0, interp_sect_size);
/* Now we need to figure out where the dynamic linker was
loaded so that we can load its symbols and place a breakpoint
@ -1060,7 +1239,7 @@ enable_break (void)
TRY_CATCH (ex, RETURN_MASK_ALL)
{
tmp_bfd = solib_bfd_open (buf);
tmp_bfd = solib_bfd_open (interp_name);
}
if (tmp_bfd == NULL)
goto bkpt_at_symbol;
@ -1075,7 +1254,7 @@ enable_break (void)
so = master_so_list ();
while (so)
{
if (svr4_same_1 (buf, so->so_original_name))
if (svr4_same_1 (interp_name, so->so_original_name))
{
load_addr_found = 1;
loader_found_in_list = 1;
@ -1104,7 +1283,7 @@ enable_break (void)
if (!loader_found_in_list)
{
debug_loader_name = xstrdup (buf);
debug_loader_name = xstrdup (interp_name);
debug_loader_offset_p = 1;
debug_loader_offset = load_addr;
solib_add (NULL, 0, &current_target, auto_solib_add);
@ -1152,12 +1331,14 @@ enable_break (void)
if (sym_addr != 0)
{
create_solib_event_breakpoint (load_addr + sym_addr);
xfree (interp_name);
return 1;
}
/* For whatever reason we couldn't set a breakpoint in the dynamic
linker. Warn and drop into the old code. */
bkpt_at_symbol:
xfree (interp_name);
warning (_("Unable to find dynamic linker breakpoint function.\n"
"GDB will be unable to debug shared library initializers\n"
"and track explicitly loaded dynamic code."));