| Message ID | 20180214114138.GX5867@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | Handle PowerPC64 ELFv1 function descriptors in libbacktrace (PR other/82368) | expand |
Hi Jakub, On Wed, Feb 14, 2018 at 12:41:38PM +0100, Jakub Jelinek wrote: > As mentioned in detail in the PR, PowerPC64 ELFv1 function symbols > point to function descriptors in .opd section rather than actual > code, and one needs to read the code address from the .opd section > in order to associate symbols with .text addresses. > > Fixed thusly, bootstrapped/regtested on powerpc64-linux (-m32/-m64 > testing) and powerpc64le-linux, ok for trunk? > > 2018-02-14 Jakub Jelinek <jakub@redhat.com> > > PR other/82368 > * elf.c (EM_PPC64, EF_PPC64_ABI): Undefine and define. > (struct elf_ppc64_opd_data): New type. > (elf_initialize_syminfo): Add opd argument, handle symbols > pointing into the PowerPC64 ELFv1 .opd section. > (elf_add): Read .opd section on PowerPC64 ELFv1, pass pointer > to structure with .opd data to elf_initialize_syminfo. Looks good to me; you may want a libbacktrace maintainer though. Segher
On Wed, Feb 14, 2018 at 3:41 AM, Jakub Jelinek <jakub@redhat.com> wrote: > > As mentioned in detail in the PR, PowerPC64 ELFv1 function symbols > point to function descriptors in .opd section rather than actual > code, and one needs to read the code address from the .opd section > in order to associate symbols with .text addresses. > > Fixed thusly, bootstrapped/regtested on powerpc64-linux (-m32/-m64 > testing) and powerpc64le-linux, ok for trunk? > > 2018-02-14 Jakub Jelinek <jakub@redhat.com> > > PR other/82368 > * elf.c (EM_PPC64, EF_PPC64_ABI): Undefine and define. > (struct elf_ppc64_opd_data): New type. > (elf_initialize_syminfo): Add opd argument, handle symbols > pointing into the PowerPC64 ELFv1 .opd section. > (elf_add): Read .opd section on PowerPC64 ELFv1, pass pointer > to structure with .opd data to elf_initialize_syminfo. This is OK. Thanks for taking this on. Ian
On 14/02/18 11:41, Jakub Jelinek wrote: > Hi! > > As mentioned in detail in the PR, PowerPC64 ELFv1 function symbols > point to function descriptors in .opd section rather than actual > code, and one needs to read the code address from the .opd section > in order to associate symbols with .text addresses. > > Fixed thusly, bootstrapped/regtested on powerpc64-linux (-m32/-m64 > testing) and powerpc64le-linux, ok for trunk? > > 2018-02-14 Jakub Jelinek <jakub@redhat.com> > > PR other/82368 > * elf.c (EM_PPC64, EF_PPC64_ABI): Undefine and define. > (struct elf_ppc64_opd_data): New type. > (elf_initialize_syminfo): Add opd argument, handle symbols > pointing into the PowerPC64 ELFv1 .opd section. > (elf_add): Read .opd section on PowerPC64 ELFv1, pass pointer > to structure with .opd data to elf_initialize_syminfo. > > --- libbacktrace/elf.c.jj 2018-02-08 20:46:10.671242369 +0000 > +++ libbacktrace/elf.c 2018-02-14 08:39:06.674088951 +0000 ... > @@ -2857,6 +2889,23 @@ elf_add (struct backtrace_state *state, > debuglink_crc = *(const uint32_t*)(debuglink_data + crc_offset); > } > } > + > + /* Read the .opd section on PowerPC64 ELFv1. */ > + if (ehdr.e_machine == EM_PPC64 > + && (ehdr.e_flags & EF_PPC64_ABI) < 2 > + && shdr->sh_type == SHT_PROGBITS this broke baremetal arm targets (e.g. aarch64-none-elf with newlib) ...src/gcc/libbacktrace/elf.c: In function 'elf_add': ...src/gcc/libbacktrace/elf.c:2896:24: error: 'SHT_PROGBITS' undeclared (first use in this function) && shdr->sh_type == SHT_PROGBITS ^~~~~~~~~~~~ > + && strcmp (name, ".opd") == 0) > + { > + if (!backtrace_get_view (state, descriptor, shdr->sh_offset, > + shdr->sh_size, error_callback, data, > + &opd_data.view)) > + goto fail; > + > + opd = &opd_data; > + opd->addr = shdr->sh_addr; > + opd->data = (const char *) opd_data.view.data; > + opd->size = shdr->sh_size; > + } > } > > if (symtab_shndx == 0)
On Thu, Feb 15, 2018 at 11:08:20AM +0000, Szabolcs Nagy wrote: > > --- libbacktrace/elf.c.jj 2018-02-08 20:46:10.671242369 +0000 > > +++ libbacktrace/elf.c 2018-02-14 08:39:06.674088951 +0000 > ... > > @@ -2857,6 +2889,23 @@ elf_add (struct backtrace_state *state, > > debuglink_crc = *(const uint32_t*)(debuglink_data + crc_offset); > > } > > } > > + > > + /* Read the .opd section on PowerPC64 ELFv1. */ > > + if (ehdr.e_machine == EM_PPC64 > > + && (ehdr.e_flags & EF_PPC64_ABI) < 2 > > + && shdr->sh_type == SHT_PROGBITS > > this broke baremetal arm targets (e.g. aarch64-none-elf with newlib) > > ...src/gcc/libbacktrace/elf.c: In function 'elf_add': > ...src/gcc/libbacktrace/elf.c:2896:24: error: 'SHT_PROGBITS' undeclared (first use in this function) > > && shdr->sh_type == SHT_PROGBITS > ^~~~~~~~~~~~ Oops, sorry, fixed thusly, committed as obvious to trunk. 2018-02-15 Jakub Jelinek <jakub@redhat.com> PR other/82368 * elf.c (SHT_PROGBITS): Undefine and define. --- libbacktrace/elf.c.jj 2018-02-14 15:19:13.849333101 +0100 +++ libbacktrace/elf.c 2018-02-15 12:30:53.948579969 +0100 @@ -170,6 +170,7 @@ dl_iterate_phdr (int (*callback) (struct #undef SHN_LORESERVE #undef SHN_XINDEX #undef SHN_UNDEF +#undef SHT_PROGBITS #undef SHT_SYMTAB #undef SHT_STRTAB #undef SHT_DYNSYM @@ -267,6 +268,7 @@ typedef struct { #define SHN_LORESERVE 0xFF00 /* Begin range of reserved indices */ #define SHN_XINDEX 0xFFFF /* Section index is held elsewhere */ +#define SHT_PROGBITS 1 #define SHT_SYMTAB 2 #define SHT_STRTAB 3 #define SHT_DYNSYM 11 Jakub
--- libbacktrace/elf.c.jj 2018-02-08 20:46:10.671242369 +0000 +++ libbacktrace/elf.c 2018-02-14 08:39:06.674088951 +0000 @@ -165,6 +165,8 @@ dl_iterate_phdr (int (*callback) (struct #undef ELFDATA2MSB #undef EV_CURRENT #undef ET_DYN +#undef EM_PPC64 +#undef EF_PPC64_ABI #undef SHN_LORESERVE #undef SHN_XINDEX #undef SHN_UNDEF @@ -245,6 +247,9 @@ typedef struct { #define ET_DYN 3 +#define EM_PPC64 21 +#define EF_PPC64_ABI 3 + typedef struct { b_elf_word sh_name; /* Section name, index in string tbl */ b_elf_word sh_type; /* Type of section */ @@ -405,6 +410,20 @@ struct elf_syminfo_data size_t count; }; +/* Information about PowerPC64 ELFv1 .opd section. */ + +struct elf_ppc64_opd_data +{ + /* Address of the .opd section. */ + b_elf_addr addr; + /* Section data. */ + const char *data; + /* Size of the .opd section. */ + size_t size; + /* Corresponding section view. */ + struct backtrace_view view; +}; + /* Compute the CRC-32 of BUF/LEN. This uses the CRC used for .gnu_debuglink files. */ @@ -569,7 +588,8 @@ elf_initialize_syminfo (struct backtrace const unsigned char *symtab_data, size_t symtab_size, const unsigned char *strtab, size_t strtab_size, backtrace_error_callback error_callback, - void *data, struct elf_syminfo_data *sdata) + void *data, struct elf_syminfo_data *sdata, + struct elf_ppc64_opd_data *opd) { size_t sym_count; const b_elf_sym *sym; @@ -620,7 +640,17 @@ elf_initialize_syminfo (struct backtrace return 0; } elf_symbols[j].name = (const char *) strtab + sym->st_name; - elf_symbols[j].address = sym->st_value + base_address; + /* Special case PowerPC64 ELFv1 symbols in .opd section, if the symbol + is a function descriptor, read the actual code address from the + descriptor. */ + if (opd + && sym->st_value >= opd->addr + && sym->st_value < opd->addr + opd->size) + elf_symbols[j].address + = *(const b_elf_addr *) (opd->data + (sym->st_value - opd->addr)); + else + elf_symbols[j].address = sym->st_value; + elf_symbols[j].address += base_address; elf_symbols[j].size = sym->st_size; ++j; } @@ -2637,6 +2667,7 @@ elf_add (struct backtrace_state *state, int debug_view_valid; unsigned int using_debug_view; uint16_t *zdebug_table; + struct elf_ppc64_opd_data opd_data, *opd; if (!debuginfo) { @@ -2655,6 +2686,7 @@ elf_add (struct backtrace_state *state, debuglink_name = NULL; debuglink_crc = 0; debug_view_valid = 0; + opd = NULL; if (!backtrace_get_view (state, descriptor, 0, sizeof ehdr, error_callback, data, &ehdr_view)) @@ -2857,6 +2889,23 @@ elf_add (struct backtrace_state *state, debuglink_crc = *(const uint32_t*)(debuglink_data + crc_offset); } } + + /* Read the .opd section on PowerPC64 ELFv1. */ + if (ehdr.e_machine == EM_PPC64 + && (ehdr.e_flags & EF_PPC64_ABI) < 2 + && shdr->sh_type == SHT_PROGBITS + && strcmp (name, ".opd") == 0) + { + if (!backtrace_get_view (state, descriptor, shdr->sh_offset, + shdr->sh_size, error_callback, data, + &opd_data.view)) + goto fail; + + opd = &opd_data; + opd->addr = shdr->sh_addr; + opd->data = (const char *) opd_data.view.data; + opd->size = shdr->sh_size; + } } if (symtab_shndx == 0) @@ -2898,7 +2947,7 @@ elf_add (struct backtrace_state *state, if (!elf_initialize_syminfo (state, base_address, symtab_view.data, symtab_shdr->sh_size, strtab_view.data, strtab_shdr->sh_size, - error_callback, data, sdata)) + error_callback, data, sdata, opd)) { backtrace_free (state, sdata, sizeof *sdata, error_callback, data); goto fail; @@ -2951,6 +3000,12 @@ elf_add (struct backtrace_state *state, buildid_view_valid = 0; } + if (opd) + { + backtrace_release_view (state, &opd->view, error_callback, data); + opd = NULL; + } + if (debuglink_name != NULL) { int d; @@ -3139,6 +3194,8 @@ elf_add (struct backtrace_state *state, backtrace_release_view (state, &buildid_view, error_callback, data); if (debug_view_valid) backtrace_release_view (state, &debug_view, error_callback, data); + if (opd) + backtrace_release_view (state, &opd->view, error_callback, data); if (descriptor != -1) backtrace_close (descriptor, error_callback, data); return 0;