| /* Target-dependent code for OpenBSD/amd64. |
| |
| Copyright (C) 2003-2021 Free Software Foundation, Inc. |
| |
| This file is part of GDB. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| #include "defs.h" |
| #include "frame.h" |
| #include "frame-unwind.h" |
| #include "gdbcore.h" |
| #include "symtab.h" |
| #include "objfiles.h" |
| #include "osabi.h" |
| #include "regcache.h" |
| #include "regset.h" |
| #include "target.h" |
| #include "trad-frame.h" |
| |
| #include "obsd-tdep.h" |
| #include "amd64-tdep.h" |
| #include "i387-tdep.h" |
| #include "gdbsupport/x86-xstate.h" |
| #include "solib-svr4.h" |
| #include "bsd-uthread.h" |
| |
| /* Support for signal handlers. */ |
| |
| /* Default page size. */ |
| static const int amd64obsd_page_size = 4096; |
| |
| /* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp |
| routine. */ |
| |
| static int |
| amd64obsd_sigtramp_p (struct frame_info *this_frame) |
| { |
| CORE_ADDR pc = get_frame_pc (this_frame); |
| CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1)); |
| const gdb_byte osigreturn[] = |
| { |
| 0x48, 0xc7, 0xc0, |
| 0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */ |
| 0xcd, 0x80 /* int $0x80 */ |
| }; |
| const gdb_byte sigreturn[] = |
| { |
| 0x48, 0xc7, 0xc0, |
| 0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */ |
| 0x0f, 0x05 /* syscall */ |
| }; |
| size_t buflen = (sizeof sigreturn) + 1; |
| gdb_byte *buf; |
| const char *name; |
| |
| /* If the function has a valid symbol name, it isn't a |
| trampoline. */ |
| find_pc_partial_function (pc, &name, NULL, NULL); |
| if (name != NULL) |
| return 0; |
| |
| /* If the function lives in a valid section (even without a starting |
| point) it isn't a trampoline. */ |
| if (find_pc_section (pc) != NULL) |
| return 0; |
| |
| /* If we can't read the instructions at START_PC, return zero. */ |
| buf = (gdb_byte *) alloca ((sizeof sigreturn) + 1); |
| if (!safe_frame_unwind_memory (this_frame, start_pc + 6, {buf, buflen})) |
| return 0; |
| |
| /* Check for sigreturn(2). Depending on how the assembler encoded |
| the `movq %rsp, %rdi' instruction, the code starts at offset 6 or |
| 7. OpenBSD 5.0 and later use the `syscall' instruction. Older |
| versions use `int $0x80'. Check for both. */ |
| if (memcmp (buf, sigreturn, sizeof sigreturn) |
| && memcmp (buf + 1, sigreturn, sizeof sigreturn) |
| && memcmp (buf, osigreturn, sizeof osigreturn) |
| && memcmp (buf + 1, osigreturn, sizeof osigreturn)) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the |
| address of the associated sigcontext structure. */ |
| |
| static CORE_ADDR |
| amd64obsd_sigcontext_addr (struct frame_info *this_frame) |
| { |
| CORE_ADDR pc = get_frame_pc (this_frame); |
| ULONGEST offset = (pc & (amd64obsd_page_size - 1)); |
| |
| /* The %rsp register points at `struct sigcontext' upon entry of a |
| signal trampoline. The relevant part of the trampoline is |
| |
| call *%rax |
| movq %rsp, %rdi |
| pushq %rdi |
| movq $SYS_sigreturn,%rax |
| int $0x80 |
| |
| (see /usr/src/sys/arch/amd64/amd64/locore.S). The `pushq' |
| instruction clobbers %rsp, but its value is saved in `%rdi'. */ |
| |
| if (offset > 5) |
| return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM); |
| else |
| return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM); |
| } |
| |
| /* OpenBSD 3.5 or later. */ |
| |
| /* Mapping between the general-purpose registers in `struct reg' |
| format and GDB's register cache layout. */ |
| |
| /* From <machine/reg.h>. */ |
| int amd64obsd_r_reg_offset[] = |
| { |
| 14 * 8, /* %rax */ |
| 13 * 8, /* %rbx */ |
| 3 * 8, /* %rcx */ |
| 2 * 8, /* %rdx */ |
| 1 * 8, /* %rsi */ |
| 0 * 8, /* %rdi */ |
| 12 * 8, /* %rbp */ |
| 15 * 8, /* %rsp */ |
| 4 * 8, /* %r8 .. */ |
| 5 * 8, |
| 6 * 8, |
| 7 * 8, |
| 8 * 8, |
| 9 * 8, |
| 10 * 8, |
| 11 * 8, /* ... %r15 */ |
| 16 * 8, /* %rip */ |
| 17 * 8, /* %eflags */ |
| 18 * 8, /* %cs */ |
| 19 * 8, /* %ss */ |
| 20 * 8, /* %ds */ |
| 21 * 8, /* %es */ |
| 22 * 8, /* %fs */ |
| 23 * 8 /* %gs */ |
| }; |
| |
| /* From <machine/signal.h>. */ |
| static int amd64obsd_sc_reg_offset[] = |
| { |
| 14 * 8, /* %rax */ |
| 13 * 8, /* %rbx */ |
| 3 * 8, /* %rcx */ |
| 2 * 8, /* %rdx */ |
| 1 * 8, /* %rsi */ |
| 0 * 8, /* %rdi */ |
| 12 * 8, /* %rbp */ |
| 24 * 8, /* %rsp */ |
| 4 * 8, /* %r8 ... */ |
| 5 * 8, |
| 6 * 8, |
| 7 * 8, |
| 8 * 8, |
| 9 * 8, |
| 10 * 8, |
| 11 * 8, /* ... %r15 */ |
| 21 * 8, /* %rip */ |
| 23 * 8, /* %eflags */ |
| 22 * 8, /* %cs */ |
| 25 * 8, /* %ss */ |
| 18 * 8, /* %ds */ |
| 17 * 8, /* %es */ |
| 16 * 8, /* %fs */ |
| 15 * 8 /* %gs */ |
| }; |
| |
| /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c. */ |
| static int amd64obsd_uthread_reg_offset[] = |
| { |
| 19 * 8, /* %rax */ |
| 16 * 8, /* %rbx */ |
| 18 * 8, /* %rcx */ |
| 17 * 8, /* %rdx */ |
| 14 * 8, /* %rsi */ |
| 13 * 8, /* %rdi */ |
| 15 * 8, /* %rbp */ |
| -1, /* %rsp */ |
| 12 * 8, /* %r8 ... */ |
| 11 * 8, |
| 10 * 8, |
| 9 * 8, |
| 8 * 8, |
| 7 * 8, |
| 6 * 8, |
| 5 * 8, /* ... %r15 */ |
| 20 * 8, /* %rip */ |
| 4 * 8, /* %eflags */ |
| 21 * 8, /* %cs */ |
| -1, /* %ss */ |
| 3 * 8, /* %ds */ |
| 2 * 8, /* %es */ |
| 1 * 8, /* %fs */ |
| 0 * 8 /* %gs */ |
| }; |
| |
| /* Offset within the thread structure where we can find the saved |
| stack pointer (%esp). */ |
| #define AMD64OBSD_UTHREAD_RSP_OFFSET 400 |
| |
| static void |
| amd64obsd_supply_uthread (struct regcache *regcache, |
| int regnum, CORE_ADDR addr) |
| { |
| struct gdbarch *gdbarch = regcache->arch (); |
| enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET; |
| CORE_ADDR sp = 0; |
| gdb_byte buf[8]; |
| int i; |
| |
| gdb_assert (regnum >= -1); |
| |
| if (regnum == -1 || regnum == AMD64_RSP_REGNUM) |
| { |
| int offset; |
| |
| /* Fetch stack pointer from thread structure. */ |
| sp = read_memory_unsigned_integer (sp_addr, 8, byte_order); |
| |
| /* Adjust the stack pointer such that it looks as if we just |
| returned from _thread_machdep_switch. */ |
| offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8; |
| store_unsigned_integer (buf, 8, byte_order, sp + offset); |
| regcache->raw_supply (AMD64_RSP_REGNUM, buf); |
| } |
| |
| for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++) |
| { |
| if (amd64obsd_uthread_reg_offset[i] != -1 |
| && (regnum == -1 || regnum == i)) |
| { |
| /* Fetch stack pointer from thread structure (if we didn't |
| do so already). */ |
| if (sp == 0) |
| sp = read_memory_unsigned_integer (sp_addr, 8, byte_order); |
| |
| /* Read the saved register from the stack frame. */ |
| read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8); |
| regcache->raw_supply (i, buf); |
| } |
| } |
| } |
| |
| static void |
| amd64obsd_collect_uthread (const struct regcache *regcache, |
| int regnum, CORE_ADDR addr) |
| { |
| struct gdbarch *gdbarch = regcache->arch (); |
| enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET; |
| CORE_ADDR sp = 0; |
| gdb_byte buf[8]; |
| int i; |
| |
| gdb_assert (regnum >= -1); |
| |
| if (regnum == -1 || regnum == AMD64_RSP_REGNUM) |
| { |
| int offset; |
| |
| /* Calculate the stack pointer (frame pointer) that will be |
| stored into the thread structure. */ |
| offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8; |
| regcache->raw_collect (AMD64_RSP_REGNUM, buf); |
| sp = extract_unsigned_integer (buf, 8, byte_order) - offset; |
| |
| /* Store the stack pointer. */ |
| write_memory_unsigned_integer (sp_addr, 8, byte_order, sp); |
| |
| /* The stack pointer was (potentially) modified. Make sure we |
| build a proper stack frame. */ |
| regnum = -1; |
| } |
| |
| for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++) |
| { |
| if (amd64obsd_uthread_reg_offset[i] != -1 |
| && (regnum == -1 || regnum == i)) |
| { |
| /* Fetch stack pointer from thread structure (if we didn't |
| calculate it already). */ |
| if (sp == 0) |
| sp = read_memory_unsigned_integer (sp_addr, 8, byte_order); |
| |
| /* Write the register into the stack frame. */ |
| regcache->raw_collect (i, buf); |
| write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8); |
| } |
| } |
| } |
| /* Kernel debugging support. */ |
| |
| /* From <machine/frame.h>. Easy since `struct trapframe' matches |
| `struct sigcontext'. */ |
| #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset |
| |
| static struct trad_frame_cache * |
| amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache) |
| { |
| struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| struct trad_frame_cache *cache; |
| CORE_ADDR func, sp, addr; |
| ULONGEST cs; |
| const char *name; |
| int i; |
| |
| if (*this_cache) |
| return (struct trad_frame_cache *) *this_cache; |
| |
| cache = trad_frame_cache_zalloc (this_frame); |
| *this_cache = cache; |
| |
| func = get_frame_func (this_frame); |
| sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM); |
| |
| find_pc_partial_function (func, &name, NULL, NULL); |
| if (name && startswith (name, "Xintr")) |
| addr = sp + 8; /* It's an interrupt frame. */ |
| else |
| addr = sp; |
| |
| for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++) |
| if (amd64obsd_tf_reg_offset[i] != -1) |
| trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]); |
| |
| /* Read %cs from trap frame. */ |
| addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM]; |
| cs = read_memory_unsigned_integer (addr, 8, byte_order); |
| if ((cs & I386_SEL_RPL) == I386_SEL_UPL) |
| { |
| /* Trap from user space; terminate backtrace. */ |
| trad_frame_set_id (cache, outer_frame_id); |
| } |
| else |
| { |
| /* Construct the frame ID using the function start. */ |
| trad_frame_set_id (cache, frame_id_build (sp + 16, func)); |
| } |
| |
| return cache; |
| } |
| |
| static void |
| amd64obsd_trapframe_this_id (struct frame_info *this_frame, |
| void **this_cache, struct frame_id *this_id) |
| { |
| struct trad_frame_cache *cache = |
| amd64obsd_trapframe_cache (this_frame, this_cache); |
| |
| trad_frame_get_id (cache, this_id); |
| } |
| |
| static struct value * |
| amd64obsd_trapframe_prev_register (struct frame_info *this_frame, |
| void **this_cache, int regnum) |
| { |
| struct trad_frame_cache *cache = |
| amd64obsd_trapframe_cache (this_frame, this_cache); |
| |
| return trad_frame_get_register (cache, this_frame, regnum); |
| } |
| |
| static int |
| amd64obsd_trapframe_sniffer (const struct frame_unwind *self, |
| struct frame_info *this_frame, |
| void **this_prologue_cache) |
| { |
| ULONGEST cs; |
| const char *name; |
| |
| /* Check Current Privilege Level and bail out if we're not executing |
| in kernel space. */ |
| cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM); |
| if ((cs & I386_SEL_RPL) == I386_SEL_UPL) |
| return 0; |
| |
| find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL); |
| return (name && ((strcmp (name, "calltrap") == 0) |
| || (strcmp (name, "osyscall1") == 0) |
| || (strcmp (name, "Xsyscall") == 0) |
| || (startswith (name, "Xintr")))); |
| } |
| |
| static const struct frame_unwind amd64obsd_trapframe_unwind = |
| { |
| /* FIXME: kettenis/20051219: This really is more like an interrupt |
| frame, but SIGTRAMP_FRAME would print <signal handler called>, |
| which really is not what we want here. */ |
| "amd64 openbsd trap", |
| NORMAL_FRAME, |
| default_frame_unwind_stop_reason, |
| amd64obsd_trapframe_this_id, |
| amd64obsd_trapframe_prev_register, |
| NULL, |
| amd64obsd_trapframe_sniffer |
| }; |
| |
| |
| static void |
| amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| { |
| struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| |
| amd64_init_abi (info, gdbarch, |
| amd64_target_description (X86_XSTATE_SSE_MASK, true)); |
| obsd_init_abi (info, gdbarch); |
| |
| /* Initialize general-purpose register set details. */ |
| tdep->gregset_reg_offset = amd64obsd_r_reg_offset; |
| tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset); |
| tdep->sizeof_gregset = 24 * 8; |
| |
| tdep->jb_pc_offset = 7 * 8; |
| |
| tdep->sigtramp_p = amd64obsd_sigtramp_p; |
| tdep->sigcontext_addr = amd64obsd_sigcontext_addr; |
| tdep->sc_reg_offset = amd64obsd_sc_reg_offset; |
| tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset); |
| |
| /* OpenBSD provides a user-level threads implementation. */ |
| bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread); |
| bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread); |
| |
| /* OpenBSD uses SVR4-style shared libraries. */ |
| set_solib_svr4_fetch_link_map_offsets |
| (gdbarch, svr4_lp64_fetch_link_map_offsets); |
| |
| /* Unwind kernel trap frames correctly. */ |
| frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind); |
| } |
| |
| void _initialize_amd64obsd_tdep (); |
| void |
| _initialize_amd64obsd_tdep () |
| { |
| /* The OpenBSD/amd64 native dependent code makes this assumption. */ |
| gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS); |
| |
| gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, |
| GDB_OSABI_OPENBSD, amd64obsd_init_abi); |
| } |