From 80ad340c90234f7294ee71468c984e7f853d9bb6 Mon Sep 17 00:00:00 2001 From: Mihails Strasuns Date: Mon, 17 Feb 2020 11:36:47 +0100 Subject: [PATCH] [gdb/testsuite] use -Ttext-segment for jit-elf tests Removes the need to manually relocate loaded ELF binary by using a fixed constant as both mmap base address and as a requested first segment address supplied to the linker. In future will enable JIT tests with a valid DWARF debug info. Current tests still need to compile without a debug info though, because they do a function name modification. gdb/testsuite/ChangeLog: 2020-02-18 Mihails Strasuns * lib/jit-elf-helpers.exp: Supply -Ttext-segment linker flag and define LOAD_ADDRESS/LOAD_INCREMENT macros for the compiled binaries. * gdb.base/jit-elf-main.c: Use LOAD_ADDRESS/LOAD_INCREMENT to calculate the mmap address. --- gdb/testsuite/gdb.base/jit-elf-main.c | 27 +++++++++++---------- gdb/testsuite/lib/jit-elf-helpers.exp | 34 ++++++++++++++++++++++++--- 2 files changed, 46 insertions(+), 15 deletions(-) diff --git a/gdb/testsuite/gdb.base/jit-elf-main.c b/gdb/testsuite/gdb.base/jit-elf-main.c index acfd17d4179..be7185ef1a1 100644 --- a/gdb/testsuite/gdb.base/jit-elf-main.c +++ b/gdb/testsuite/gdb.base/jit-elf-main.c @@ -51,20 +51,16 @@ usage (void) exit (1); } -/* Update .p_vaddr and .sh_addr as if the code was JITted to ADDR. */ +/* Rename jit_function_XXXX to match idx */ static void -update_locations (const void *const addr, int idx) +update_name (const void *const addr, int idx) { const ElfW (Ehdr) *const ehdr = (ElfW (Ehdr) *)addr; ElfW (Shdr) *const shdr = (ElfW (Shdr) *)((char *)addr + ehdr->e_shoff); ElfW (Phdr) *const phdr = (ElfW (Phdr) *)((char *)addr + ehdr->e_phoff); int i; - for (i = 0; i < ehdr->e_phnum; ++i) - if (phdr[i].p_type == PT_LOAD) - phdr[i].p_vaddr += (ElfW (Addr))addr; - for (i = 0; i < ehdr->e_shnum; ++i) { if (shdr[i].sh_type == SHT_STRTAB) @@ -81,9 +77,6 @@ update_locations (const void *const addr, int idx) if (strcmp (p, "jit_function_XXXX") == 0) sprintf (p, "jit_function_%04d", idx); } - - if (shdr[i].sh_flags & SHF_ALLOC) - shdr[i].sh_addr += (ElfW (Addr))addr; } } @@ -96,6 +89,15 @@ update_locations (const void *const addr, int idx) #define MAIN main #endif +/* Must be defined by .exp file when compiling to know + what address to map the ELF binary to. */ +#ifndef LOAD_ADDRESS +#error "Must define LOAD_ADDRESS" +#endif +#ifndef LOAD_INCREMENT +#error "Must define LOAD_INCREMENT" +#endif + /* Used to spin waiting for GDB. */ volatile int wait_for_gdb = ATTACH; #define WAIT_FOR_GDB do {} while (wait_for_gdb) @@ -139,8 +141,9 @@ MAIN (int argc, char *argv[]) exit (1); } - const void *const addr = mmap (0, st.st_size, PROT_READ|PROT_WRITE, - MAP_PRIVATE, fd, 0); + void *load_addr = (void *) (size_t) (LOAD_ADDRESS + (i - 1) * LOAD_INCREMENT); + const void *const addr = mmap (load_addr, st.st_size, PROT_READ|PROT_WRITE, + MAP_PRIVATE | MAP_FIXED, fd, 0); struct jit_code_entry *const entry = calloc (1, sizeof (*entry)); if (addr == MAP_FAILED) @@ -149,7 +152,7 @@ MAIN (int argc, char *argv[]) exit (1); } - update_locations (addr, i); + update_name (addr, i); /* Link entry at the end of the list. */ entry->symfile_addr = (const char *)addr; diff --git a/gdb/testsuite/lib/jit-elf-helpers.exp b/gdb/testsuite/lib/jit-elf-helpers.exp index 91b64f2915d..032417b373d 100644 --- a/gdb/testsuite/lib/jit-elf-helpers.exp +++ b/gdb/testsuite/lib/jit-elf-helpers.exp @@ -13,6 +13,13 @@ # You should have received a copy of the GNU General Public License # along with this program. If not, see . +# Magic constants used to calculate a starting address when linking +# "jit" shared libraries. When loaded, will be mapped by jit-elf-main +# to the same address. + +set jit_load_address 0x7000000 +set jit_load_increment 0x1000000 + # Compile jit-elf-main.c as an executable. # # BINSUFFIX is appended to the binary name. @@ -21,7 +28,13 @@ # On success, return 0. # On failure, return -1. proc compile_jit_main {main_srcfile main_binfile options} { - set options [concat $options debug] + global jit_load_address jit_load_increment + + set options [concat \ + $options \ + additional_flags=-DLOAD_ADDRESS=$jit_load_address \ + additional_flags=-DLOAD_INCREMENT=$jit_load_increment \ + debug] if { [gdb_compile ${main_srcfile} ${main_binfile} \ executable $options] != "" } { @@ -39,7 +52,13 @@ proc compile_jit_main {main_srcfile main_binfile options} { # On success, return 0. # On failure, return -1. proc compile_jit_elf_main_as_so {main_solib_srcfile main_solib_binfile options} { - set options [concat $options debug] + global jit_load_address jit_load_increment + + set options [list \ + additional_flags="-DMAIN=jit_dl_main" \ + additional_flags=-DLOAD_ADDRESS=$jit_load_address \ + additional_flags=-DLOAD_INCREMENT=$jit_load_increment \ + debug] if { [gdb_compile_shlib ${main_solib_srcfile} ${main_solib_binfile} \ $options] != "" } { @@ -56,6 +75,7 @@ proc compile_jit_elf_main_as_so {main_solib_srcfile main_solib_binfile options} # On success, return a list of target path to the shared libraries. # On failure, return -1. proc compile_and_download_n_jit_so {jit_solib_basename jit_solib_srcfile count} { + global jit_load_address jit_load_increment set binfiles_target {} for {set i 1} {$i <= $count} {incr i} { @@ -65,7 +85,15 @@ proc compile_and_download_n_jit_so {jit_solib_basename jit_solib_srcfile count} # do symbol renaming by munging on ELF symbol table, and that # wouldn't work for .debug sections. Also, output for "info # function" changes when debug info is present. - if { [gdb_compile_shlib ${jit_solib_srcfile} ${binfile} {}] != "" } { + set addr [format 0x%x [expr $jit_load_address + $jit_load_increment * [expr $i-1]]] + # Using -Ttext-segment flag to ask linked to relocate everything + # in the compiled shared library against a fixed base address. Combined + # with mapping the resulting binary to the same fixed base it allows + # to dynamically execute functions from it without any further adjustments. + set options [list \ + additional_flags=-Xlinker \ + additional_flags=-Ttext-segment=$addr] + if { [gdb_compile_shlib ${jit_solib_srcfile} ${binfile} $options] != "" } { untested "failed to compile ${jit_solib_basename}.c as a shared library" return -1 } -- 2.30.2