diff options
Diffstat (limited to 'gdb/ppc-linux-tdep.c')
| -rw-r--r-- | gdb/ppc-linux-tdep.c | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c index 54d5d9a..7781e47 100644 --- a/gdb/ppc-linux-tdep.c +++ b/gdb/ppc-linux-tdep.c @@ -941,6 +941,60 @@ ppc64_call_dummy_address (void) } +/* Return the unrelocated code address at which execution begins for + ABFD, under the 64-bit PowerPC Linux ABI. + + On that system, the ELF header's e_entry field (which is what + bfd_get_start_address gives you) is not the address of the actual + machine instruction you need to jump to, as it is on almost every + other target. Instead, it's the address of a function descriptor + for the start function. A function descriptor is a structure + containing three addresses: the entry point, the TOC pointer for + the function, and an environment pointer for the function. The + first field is what we want to return. + + So all we do is find the section containing the start address, read + the address-sized word there out of the BFD, and return that. */ +static CORE_ADDR +ppc64_linux_bfd_entry_point (struct gdbarch *gdbarch, bfd *abfd) +{ + bfd_vma start_address = bfd_get_start_address (abfd); + unsigned int addr_size = (bfd_arch_bits_per_address (abfd) + / bfd_arch_bits_per_byte (abfd)); + unsigned char *entry_pt_buf = alloca (addr_size); + asection *sec; + file_ptr desc_offset; + + /* Find a data section containing an address-sized word at + start_address. */ + for (sec = abfd->sections; sec; sec = sec->next) + { + CORE_ADDR sec_vma = bfd_get_section_vma (abfd, sec); + CORE_ADDR sec_end_vma = sec_vma + bfd_section_size (abfd, sec); + + if (sec_vma <= start_address + && start_address + addr_size <= sec_end_vma) + break; + } + if (! sec) + return 0; + + /* Okay, we've found the section. What is the function descriptor's + offset within that section? */ + desc_offset = start_address - bfd_get_section_vma (abfd, sec); + + /* Seek to the descriptor, and read the first address-sized word it + contains. */ + if (bfd_seek (abfd, sec->filepos + desc_offset, SEEK_SET) + || bfd_bread (entry_pt_buf, addr_size, abfd) != addr_size) + return 0; + + /* That's the actual code entry point. */ + return (CORE_ADDR) bfd_get (bfd_arch_bits_per_address (abfd), + abfd, entry_pt_buf); +} + + enum { ELF_NGREG = 48, ELF_NFPREG = 33, @@ -1072,6 +1126,8 @@ ppc_linux_init_abi (struct gdbarch_info info, set_gdbarch_in_solib_call_trampoline (gdbarch, ppc64_in_solib_call_trampoline); set_gdbarch_skip_trampoline_code (gdbarch, ppc64_skip_trampoline_code); + + set_gdbarch_bfd_entry_point (gdbarch, ppc64_linux_bfd_entry_point); } } |