From d86ece5e869faee022313c698e29878bfb16d5d3 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Thu, 13 Jul 2017 20:44:34 +0100 Subject: Fix x86-64 GNU/Linux crashes Ref: https://sourceware.org/ml/gdb-patches/2017-07/msg00162.html Debugging x86-64 GNU/Linux programs currently crashes GDB in tdesc_use_registers during gdbarch initialization: Program received signal SIGSEGV, Segmentation fault. 0x0000000001093eaf in htab_remove_elt_with_hash (htab=0x2ef9fa0, element=0x26af960, hash=557151073) at src/libiberty/hashtab.c:728 728 if (*slot == HTAB_EMPTY_ENTRY) (top-gdb) p slot $1 = (void **) 0x0 (top-gdb) bt #0 0x0000000001093eaf in htab_remove_elt_with_hash (htab=0x2ef9fa0, element=0x26af960, hash=557151073) at src/libiberty/hashtab.c:728 #1 0x0000000001093e79 in htab_remove_elt (htab=0x2ef9fa0, element=0x26af960) at src/libiberty/hashtab.c:714 #2 0x00000000009121b0 in tdesc_use_registers (gdbarch=0x3001240, target_desc=0x2659cb0, early_data=0x2881cb0) at src/gdb/target-descriptions.c:1328 #3 0x000000000047c93e in i386_gdbarch_init (info=..., arches=0x0) at src/gdb/i386-tdep.c:8634 #4 0x0000000000818d5f in gdbarch_find_by_info (info=...) at src/gdb/gdbarch.c:5394 #5 0x00000000007198a8 in set_gdbarch_from_file (abfd=0x2f48250) at src/gdb/arch-utils.c:618 #6 0x00000000007f21cb in exec_file_attach (filename=0x7fffffffddb0 "/home/pedro/gdb/tests/threads", from_tty=1) at src/gdb/exec.c:380 #7 0x0000000000865c18 in catch_command_errors_const (command=0x7f1d83 , arg=0x7fffffffddb0 "/home/pedro/gdb/tests/threads", from_tty=1) at src/gdb/main.c:403 #8 0x00000000008669cf in captured_main_1 (context=0x7fffffffd860) at src/gdb/main.c:1035 #9 0x0000000000866de2 in captured_main (data=0x7fffffffd860) at src/gdb/main.c:1142 #10 0x0000000000866e24 in gdb_main (args=0x7fffffffd860) at src/gdb/main.c:1160 #11 0x000000000041312d in main (argc=3, argv=0x7fffffffd968) at src/gdb/gdb.c:32 The direct cause of the crash is that we tried to remove an element from the hash which supposedly exists, but does not. (htab_remove_elt shouldn't really crash in this case, but that's secondary.) The real problem is that early_data passed to tdesc_use_registers includes regs from a target description that is not the target_desc, which violates its assumptions. The registers in question are the fs_base/gs_base registers, added by amd64_init_abi: tdesc_numbered_register (feature, tdesc_data_segments, AMD64_FSBASE_REGNUM, "fs_base"); tdesc_numbered_register (feature, tdesc_data_segments, AMD64_GSBASE_REGNUM, "gs_base"); and that happens because amd64_linux_init_abi uses amd64_init_abi as helper, but they don't coordinate on which fallback tdesc to use. amd64_init_abi does: if (! tdesc_has_registers (tdesc)) tdesc = tdesc_amd64; and then adds the fs_base/gs_base registers of the "tdesc_amd64" tdesc to the tdesc_arch_data. After amd64_init_abi returns, amd64_linux_init_abi does: if (! tdesc_has_registers (tdesc)) tdesc = tdesc_amd64_linux; tdep->tdesc = tdesc; and we end up tdesc_amd64_linux installed in tdep->tdesc. The fix is to make sure that amd64_linux_init_abi and amd64_init_abi agree on default tdesc, by adding a "default tdesc" parameter to amd64_init_abi, instead of having amd64_init_abi hardcode a default. With this, amd64_init_abi creates the fs_base/gs_base registers using the tdesc_amd64_linux tdesc. Tested on x86-64 GNU/Linux, -m64. I don't have an x32 setup handy. Thanks to John Baldwin, Yao Qi and Simon Marchi for the investigation. gdb/ChangeLog: 2017-07-13 Pedro Alves * amd64-darwin-tdep.c (x86_darwin_init_abi_64): Pass tdesc_amd64 as default tdesc. * amd64-dicos-tdep.c (amd64_dicos_init_abi): * amd64-fbsd-tdep.c (amd64fbsd_init_abi): * amd64-linux-tdep.c (amd64_linux_init_abi): Pass tdesc_amd64_linux as default tdesc. Get final tdesc from the tdep. (amd64_x32_linux_init_abi): Pass tdesc_x32_linux as default tdesc. Get final tdesc from the tdep. * amd64-nbsd-tdep.c (amd64nbsd_init_abi): Pass tdesc_amd64 as default tdesc. * amd64-obsd-tdep.c (amd64obsd_init_abi): Likewise. * amd64-sol2-tdep.c (amd64_sol2_init_abi): Likewise. * amd64-tdep.c (amd64_init_abi): Add 'default_tdesc' parameter. Use it as default tdesc. (amd64_x32_init_abi): Add 'default_tdesc' parameter, and pass it down to amd_init_abi. No longer handle fallback tdesc here. * amd64-tdep.h (tdesc_x32): Declare. (amd64_init_abi, amd64_x32_init_abi): Add 'default_tdesc' parameter. * amd64-windows-tdep.c (amd64_windows_init_abi): Pass tdesc_amd64 as default tdesc. --- gdb/amd64-darwin-tdep.c | 2 +- gdb/amd64-dicos-tdep.c | 2 +- gdb/amd64-fbsd-tdep.c | 2 +- gdb/amd64-linux-tdep.c | 16 +++++----------- gdb/amd64-nbsd-tdep.c | 2 +- gdb/amd64-obsd-tdep.c | 2 +- gdb/amd64-sol2-tdep.c | 2 +- gdb/amd64-tdep.c | 15 ++++++--------- gdb/amd64-tdep.h | 9 +++++++-- gdb/amd64-windows-tdep.c | 2 +- 10 files changed, 25 insertions(+), 29 deletions(-) diff --git a/gdb/amd64-darwin-tdep.c b/gdb/amd64-darwin-tdep.c index db400cd0c84..be26d9e3c4b 100644 --- a/gdb/amd64-darwin-tdep.c +++ b/gdb/amd64-darwin-tdep.c @@ -99,7 +99,7 @@ x86_darwin_init_abi_64 (struct gdbarch_info info, struct gdbarch *gdbarch) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); - amd64_init_abi (info, gdbarch); + amd64_init_abi (info, gdbarch, tdesc_amd64); tdep->struct_return = reg_struct_return; diff --git a/gdb/amd64-dicos-tdep.c b/gdb/amd64-dicos-tdep.c index ee408912126..7bdb167e82d 100644 --- a/gdb/amd64-dicos-tdep.c +++ b/gdb/amd64-dicos-tdep.c @@ -25,7 +25,7 @@ static void amd64_dicos_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) { - amd64_init_abi (info, gdbarch); + amd64_init_abi (info, gdbarch, tdesc_amd64); dicos_init_abi (gdbarch); } diff --git a/gdb/amd64-fbsd-tdep.c b/gdb/amd64-fbsd-tdep.c index 48bb2093252..ad4d787998d 100644 --- a/gdb/amd64-fbsd-tdep.c +++ b/gdb/amd64-fbsd-tdep.c @@ -217,7 +217,7 @@ amd64fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) tdep->gregset_num_regs = ARRAY_SIZE (amd64fbsd_r_reg_offset); tdep->sizeof_gregset = 22 * 8; - amd64_init_abi (info, gdbarch); + amd64_init_abi (info, gdbarch, tdesc_amd64); tdep->sigtramp_p = amd64fbsd_sigtramp_p; tdep->sigtramp_start = amd64fbsd_sigtramp_start_addr; diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c index 4ef0f783ab5..cf2478924b6 100644 --- a/gdb/amd64-linux-tdep.c +++ b/gdb/amd64-linux-tdep.c @@ -1863,7 +1863,6 @@ static void amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); - const struct target_desc *tdesc = info.target_desc; struct tdesc_arch_data *tdesc_data = (struct tdesc_arch_data *) info.tdep_info; const struct tdesc_feature *feature; @@ -1875,15 +1874,13 @@ amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset); tdep->sizeof_gregset = 27 * 8; - amd64_init_abi (info, gdbarch); + amd64_init_abi (info, gdbarch, tdesc_amd64_linux); + + const target_desc *tdesc = tdep->tdesc; /* Reserve a number for orig_rax. */ set_gdbarch_num_regs (gdbarch, AMD64_LINUX_NUM_REGS); - if (! tdesc_has_registers (tdesc)) - tdesc = tdesc_amd64_linux; - tdep->tdesc = tdesc; - feature = tdesc_find_feature (tdesc, "org.gnu.gdb.i386.linux"); if (feature == NULL) return; @@ -2080,7 +2077,6 @@ static void amd64_x32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); - const struct target_desc *tdesc = info.target_desc; struct tdesc_arch_data *tdesc_data = (struct tdesc_arch_data *) info.tdep_info; const struct tdesc_feature *feature; @@ -2092,14 +2088,12 @@ amd64_x32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset); tdep->sizeof_gregset = 27 * 8; - amd64_x32_init_abi (info, gdbarch); + amd64_x32_init_abi (info, gdbarch, tdesc_x32_linux); /* Reserve a number for orig_rax. */ set_gdbarch_num_regs (gdbarch, AMD64_LINUX_NUM_REGS); - if (! tdesc_has_registers (tdesc)) - tdesc = tdesc_x32_linux; - tdep->tdesc = tdesc; + const target_desc *tdesc = tdep->tdesc; feature = tdesc_find_feature (tdesc, "org.gnu.gdb.i386.linux"); if (feature == NULL) diff --git a/gdb/amd64-nbsd-tdep.c b/gdb/amd64-nbsd-tdep.c index db6f19f63ed..02bf42776e1 100644 --- a/gdb/amd64-nbsd-tdep.c +++ b/gdb/amd64-nbsd-tdep.c @@ -103,7 +103,7 @@ amd64nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) tdep->gregset_num_regs = ARRAY_SIZE (amd64nbsd_r_reg_offset); tdep->sizeof_gregset = 26 * 8; - amd64_init_abi (info, gdbarch); + amd64_init_abi (info, gdbarch, tdesc_amd64); tdep->jb_pc_offset = 7 * 8; diff --git a/gdb/amd64-obsd-tdep.c b/gdb/amd64-obsd-tdep.c index 72895b6fc6e..ad90c20b5af 100644 --- a/gdb/amd64-obsd-tdep.c +++ b/gdb/amd64-obsd-tdep.c @@ -419,7 +419,7 @@ amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); - amd64_init_abi (info, gdbarch); + amd64_init_abi (info, gdbarch, tdesc_amd64); obsd_init_abi (info, gdbarch); /* Initialize general-purpose register set details. */ diff --git a/gdb/amd64-sol2-tdep.c b/gdb/amd64-sol2-tdep.c index 51fe9dbe4fb..ca474db8b2e 100644 --- a/gdb/amd64-sol2-tdep.c +++ b/gdb/amd64-sol2-tdep.c @@ -99,7 +99,7 @@ amd64_sol2_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) tdep->gregset_num_regs = ARRAY_SIZE (amd64_sol2_gregset_reg_offset); tdep->sizeof_gregset = 28 * 8; - amd64_init_abi (info, gdbarch); + amd64_init_abi (info, gdbarch, tdesc_amd64); tdep->sigtramp_p = amd64_sol2_sigtramp_p; tdep->sigcontext_addr = amd64_sol2_mcontext_addr; diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c index 9ff7dfc5134..6171bc598d5 100644 --- a/gdb/amd64-tdep.c +++ b/gdb/amd64-tdep.c @@ -3005,7 +3005,8 @@ static const int amd64_record_regmap[] = }; void -amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) +amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch, + target_desc *default_tdesc) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); const struct target_desc *tdesc = info.target_desc; @@ -3022,7 +3023,7 @@ amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) tdep->fpregset = &amd64_fpregset; if (! tdesc_has_registers (tdesc)) - tdesc = tdesc_amd64; + tdesc = default_tdesc; tdep->tdesc = tdesc; tdep->num_core_regs = AMD64_NUM_GREGS + I387_NUM_REGS; @@ -3196,16 +3197,12 @@ amd64_x32_pseudo_register_type (struct gdbarch *gdbarch, int regnum) } void -amd64_x32_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) +amd64_x32_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch, + target_desc *default_tdesc) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); - const struct target_desc *tdesc = info.target_desc; - - amd64_init_abi (info, gdbarch); - if (! tdesc_has_registers (tdesc)) - tdesc = tdesc_x32; - tdep->tdesc = tdesc; + amd64_init_abi (info, gdbarch, default_tdesc); tdep->num_dword_regs = 17; set_tdesc_pseudo_register_type (gdbarch, amd64_x32_pseudo_register_type); diff --git a/gdb/amd64-tdep.h b/gdb/amd64-tdep.h index 87f0ba30738..88b83067f1c 100644 --- a/gdb/amd64-tdep.h +++ b/gdb/amd64-tdep.h @@ -88,6 +88,7 @@ enum amd64_regnum #define AMD64_NUM_REGS (AMD64_GSBASE_REGNUM + 1) extern struct target_desc *tdesc_amd64; +extern struct target_desc *tdesc_x32; extern struct displaced_step_closure *amd64_displaced_step_copy_insn (struct gdbarch *gdbarch, CORE_ADDR from, CORE_ADDR to, @@ -97,9 +98,13 @@ extern void amd64_displaced_step_fixup (struct gdbarch *gdbarch, CORE_ADDR from, CORE_ADDR to, struct regcache *regs); -extern void amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch); +extern void amd64_init_abi (struct gdbarch_info info, + struct gdbarch *gdbarch, + target_desc *default_tdesc); + extern void amd64_x32_init_abi (struct gdbarch_info info, - struct gdbarch *gdbarch); + struct gdbarch *gdbarch, + target_desc *default_tdesc); extern const struct target_desc *amd64_target_description (uint64_t xcr0); /* Fill register REGNUM in REGCACHE with the appropriate diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c index f1acdb9bec2..9158282cf9a 100644 --- a/gdb/amd64-windows-tdep.c +++ b/gdb/amd64-windows-tdep.c @@ -1224,7 +1224,7 @@ amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) */ frame_unwind_append_unwinder (gdbarch, &amd64_windows_frame_unwind); - amd64_init_abi (info, gdbarch); + amd64_init_abi (info, gdbarch, tdesc_amd64); windows_init_abi (info, gdbarch); -- cgit v1.2.1