| /* Native-dependent code for GNU/Linux x86-64. |
| |
| Copyright (C) 2001-2024 Free Software Foundation, Inc. |
| Contributed by Jiri Smid, SuSE Labs. |
| |
| 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 "inferior.h" |
| #include "regcache.h" |
| #include "elf/common.h" |
| #include <sys/uio.h> |
| #include "nat/gdb_ptrace.h" |
| #include <asm/prctl.h> |
| #include <sys/reg.h> |
| #include "gregset.h" |
| #include "gdb_proc_service.h" |
| |
| #include "amd64-nat.h" |
| #include "amd64-tdep.h" |
| #include "amd64-linux-tdep.h" |
| #include "i386-linux-tdep.h" |
| #include "gdbsupport/x86-xstate.h" |
| |
| #include "x86-linux-nat.h" |
| #include "nat/linux-ptrace.h" |
| #include "nat/amd64-linux-siginfo.h" |
| |
| /* This definition comes from prctl.h. Kernels older than 2.5.64 |
| do not have it. */ |
| #ifndef PTRACE_ARCH_PRCTL |
| #define PTRACE_ARCH_PRCTL 30 |
| #endif |
| |
| struct amd64_linux_nat_target final : public x86_linux_nat_target |
| { |
| /* Add our register access methods. */ |
| void fetch_registers (struct regcache *, int) override; |
| void store_registers (struct regcache *, int) override; |
| |
| bool low_siginfo_fixup (siginfo_t *ptrace, gdb_byte *inf, int direction) |
| override; |
| }; |
| |
| static amd64_linux_nat_target the_amd64_linux_nat_target; |
| |
| /* Mapping between the general-purpose registers in GNU/Linux x86-64 |
| `struct user' format and GDB's register cache layout for GNU/Linux |
| i386. |
| |
| Note that most GNU/Linux x86-64 registers are 64-bit, while the |
| GNU/Linux i386 registers are all 32-bit, but since we're |
| little-endian we get away with that. */ |
| |
| /* From <sys/reg.h> on GNU/Linux i386. */ |
| static int amd64_linux_gregset32_reg_offset[] = |
| { |
| RAX * 8, RCX * 8, /* %eax, %ecx */ |
| RDX * 8, RBX * 8, /* %edx, %ebx */ |
| RSP * 8, RBP * 8, /* %esp, %ebp */ |
| RSI * 8, RDI * 8, /* %esi, %edi */ |
| RIP * 8, EFLAGS * 8, /* %eip, %eflags */ |
| CS * 8, SS * 8, /* %cs, %ss */ |
| DS * 8, ES * 8, /* %ds, %es */ |
| FS * 8, GS * 8, /* %fs, %gs */ |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, /* MPX registers BND0 ... BND3. */ |
| -1, -1, /* MPX registers BNDCFGU, BNDSTATUS. */ |
| -1, -1, -1, -1, -1, -1, -1, -1, /* k0 ... k7 (AVX512) */ |
| -1, -1, -1, -1, -1, -1, -1, -1, /* zmm0 ... zmm7 (AVX512) */ |
| -1, /* PKEYS register PKRU */ |
| ORIG_RAX * 8 /* "orig_eax" */ |
| }; |
| |
| |
| /* Transfering the general-purpose registers between GDB, inferiors |
| and core files. */ |
| |
| /* See amd64_collect_native_gregset. This linux specific version handles |
| issues with negative EAX values not being restored correctly upon syscall |
| return when debugging 32-bit targets. It has no effect on 64-bit |
| targets. */ |
| |
| static void |
| amd64_linux_collect_native_gregset (const struct regcache *regcache, |
| void *gregs, int regnum) |
| { |
| amd64_collect_native_gregset (regcache, gregs, regnum); |
| |
| struct gdbarch *gdbarch = regcache->arch (); |
| if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32) |
| { |
| /* Sign extend EAX value to avoid potential syscall restart |
| problems. |
| |
| On Linux, when a syscall is interrupted by a signal, the |
| (kernel function implementing the) syscall may return |
| -ERESTARTSYS when a signal occurs. Doing so indicates that |
| the syscall is restartable. Then, depending on settings |
| associated with the signal handler, and after the signal |
| handler is called, the kernel can then either return -EINTR |
| or it can cause the syscall to be restarted. We are |
| concerned with the latter case here. |
| |
| On (32-bit) i386, the status (-ERESTARTSYS) is placed in the |
| EAX register. When debugging a 32-bit process from a 64-bit |
| (amd64) GDB, the debugger fetches 64-bit registers even |
| though the process being debugged is only 32-bit. The |
| register cache is only 32 bits wide though; GDB discards the |
| high 32 bits when placing 64-bit values in the 32-bit |
| regcache. Normally, this is not a problem since the 32-bit |
| process should only care about the lower 32-bit portions of |
| these registers. That said, it can happen that the 64-bit |
| value being restored will be different from the 64-bit value |
| that was originally retrieved from the kernel. The one place |
| (that we know of) where it does matter is in the kernel's |
| syscall restart code. The kernel's code for restarting a |
| syscall after a signal expects to see a negative value |
| (specifically -ERESTARTSYS) in the 64-bit RAX register in |
| order to correctly cause a syscall to be restarted. |
| |
| The call to amd64_collect_native_gregset, above, is setting |
| the high 32 bits of RAX (and other registers too) to 0. For |
| syscall restart, we need to sign extend EAX so that RAX will |
| appear as a negative value when EAX is set to -ERESTARTSYS. |
| This in turn will cause the signal handling code in the |
| kernel to recognize -ERESTARTSYS which will in turn cause the |
| syscall to be restarted. |
| |
| The test case gdb.base/interrupt.exp tests for this problem. |
| Without this sign extension code in place, it'll show |
| a number of failures when testing against unix/-m32. */ |
| |
| if (regnum == -1 || regnum == I386_EAX_REGNUM) |
| { |
| void *ptr = ((gdb_byte *) gregs |
| + amd64_linux_gregset32_reg_offset[I386_EAX_REGNUM]); |
| |
| *(int64_t *) ptr = *(int32_t *) ptr; |
| } |
| } |
| } |
| |
| /* Fill GDB's register cache with the general-purpose register values |
| in *GREGSETP. */ |
| |
| void |
| supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp) |
| { |
| amd64_supply_native_gregset (regcache, gregsetp, -1); |
| } |
| |
| /* Fill register REGNUM (if it is a general-purpose register) in |
| *GREGSETP with the value in GDB's register cache. If REGNUM is -1, |
| do this for all registers. */ |
| |
| void |
| fill_gregset (const struct regcache *regcache, |
| elf_gregset_t *gregsetp, int regnum) |
| { |
| amd64_linux_collect_native_gregset (regcache, gregsetp, regnum); |
| } |
| |
| /* Transfering floating-point registers between GDB, inferiors and cores. */ |
| |
| /* Fill GDB's register cache with the floating-point and SSE register |
| values in *FPREGSETP. */ |
| |
| void |
| supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp) |
| { |
| amd64_supply_fxsave (regcache, -1, fpregsetp); |
| } |
| |
| /* Fill register REGNUM (if it is a floating-point or SSE register) in |
| *FPREGSETP with the value in GDB's register cache. If REGNUM is |
| -1, do this for all registers. */ |
| |
| void |
| fill_fpregset (const struct regcache *regcache, |
| elf_fpregset_t *fpregsetp, int regnum) |
| { |
| amd64_collect_fxsave (regcache, regnum, fpregsetp); |
| } |
| |
| |
| /* Transferring arbitrary registers between GDB and inferior. */ |
| |
| /* Fetch register REGNUM from the child process. If REGNUM is -1, do |
| this for all registers (including the floating point and SSE |
| registers). */ |
| |
| void |
| amd64_linux_nat_target::fetch_registers (struct regcache *regcache, int regnum) |
| { |
| struct gdbarch *gdbarch = regcache->arch (); |
| const i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch); |
| int tid; |
| |
| /* GNU/Linux LWP ID's are process ID's. */ |
| tid = regcache->ptid ().lwp (); |
| if (tid == 0) |
| tid = regcache->ptid ().pid (); /* Not a threaded program. */ |
| |
| if (regnum == -1 || amd64_native_gregset_supplies_p (gdbarch, regnum)) |
| { |
| elf_gregset_t regs; |
| |
| if (ptrace (PTRACE_GETREGS, tid, 0, (long) ®s) < 0) |
| perror_with_name (_("Couldn't get registers")); |
| |
| amd64_supply_native_gregset (regcache, ®s, -1); |
| if (regnum != -1) |
| return; |
| } |
| |
| if (regnum == -1 || !amd64_native_gregset_supplies_p (gdbarch, regnum)) |
| { |
| elf_fpregset_t fpregs; |
| |
| if (have_ptrace_getregset == TRIBOOL_TRUE) |
| { |
| /* Pre-4.14 kernels have a bug (fixed by commit 0852b374173b |
| "x86/fpu: Add FPU state copying quirk to handle XRSTOR failure on |
| Intel Skylake CPUs") that sometimes causes the mxcsr location in |
| xstateregs not to be copied by PTRACE_GETREGSET. Make sure that |
| the location is at least initialized with a defined value. */ |
| gdb::byte_vector xstateregs (tdep->xsave_layout.sizeof_xsave, 0); |
| struct iovec iov; |
| |
| iov.iov_base = xstateregs.data (); |
| iov.iov_len = xstateregs.size (); |
| if (ptrace (PTRACE_GETREGSET, tid, |
| (unsigned int) NT_X86_XSTATE, (long) &iov) < 0) |
| perror_with_name (_("Couldn't get extended state status")); |
| |
| amd64_supply_xsave (regcache, -1, xstateregs.data ()); |
| } |
| else |
| { |
| if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0) |
| perror_with_name (_("Couldn't get floating point status")); |
| |
| amd64_supply_fxsave (regcache, -1, &fpregs); |
| } |
| } |
| } |
| |
| /* Store register REGNUM back into the child process. If REGNUM is |
| -1, do this for all registers (including the floating-point and SSE |
| registers). */ |
| |
| void |
| amd64_linux_nat_target::store_registers (struct regcache *regcache, int regnum) |
| { |
| struct gdbarch *gdbarch = regcache->arch (); |
| const i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch); |
| int tid; |
| |
| /* GNU/Linux LWP ID's are process ID's. */ |
| tid = regcache->ptid ().lwp (); |
| if (tid == 0) |
| tid = regcache->ptid ().pid (); /* Not a threaded program. */ |
| |
| if (regnum == -1 || amd64_native_gregset_supplies_p (gdbarch, regnum)) |
| { |
| elf_gregset_t regs; |
| |
| if (ptrace (PTRACE_GETREGS, tid, 0, (long) ®s) < 0) |
| perror_with_name (_("Couldn't get registers")); |
| |
| amd64_linux_collect_native_gregset (regcache, ®s, regnum); |
| |
| if (ptrace (PTRACE_SETREGS, tid, 0, (long) ®s) < 0) |
| perror_with_name (_("Couldn't write registers")); |
| |
| if (regnum != -1) |
| return; |
| } |
| |
| if (regnum == -1 || !amd64_native_gregset_supplies_p (gdbarch, regnum)) |
| { |
| elf_fpregset_t fpregs; |
| |
| if (have_ptrace_getregset == TRIBOOL_TRUE) |
| { |
| gdb::byte_vector xstateregs (tdep->xsave_layout.sizeof_xsave); |
| struct iovec iov; |
| |
| iov.iov_base = xstateregs.data (); |
| iov.iov_len = xstateregs.size (); |
| if (ptrace (PTRACE_GETREGSET, tid, |
| (unsigned int) NT_X86_XSTATE, (long) &iov) < 0) |
| perror_with_name (_("Couldn't get extended state status")); |
| |
| amd64_collect_xsave (regcache, regnum, xstateregs.data (), 0); |
| |
| if (ptrace (PTRACE_SETREGSET, tid, |
| (unsigned int) NT_X86_XSTATE, (long) &iov) < 0) |
| perror_with_name (_("Couldn't write extended state status")); |
| } |
| else |
| { |
| if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0) |
| perror_with_name (_("Couldn't get floating point status")); |
| |
| amd64_collect_fxsave (regcache, regnum, &fpregs); |
| |
| if (ptrace (PTRACE_SETFPREGS, tid, 0, (long) &fpregs) < 0) |
| perror_with_name (_("Couldn't write floating point status")); |
| } |
| } |
| } |
| |
| |
| /* This function is called by libthread_db as part of its handling of |
| a request for a thread's local storage address. */ |
| |
| ps_err_e |
| ps_get_thread_area (struct ps_prochandle *ph, |
| lwpid_t lwpid, int idx, void **base) |
| { |
| if (gdbarch_bfd_arch_info (ph->thread->inf->arch ())->bits_per_word == 32) |
| { |
| unsigned int base_addr; |
| ps_err_e result; |
| |
| result = x86_linux_get_thread_area (lwpid, (void *) (long) idx, |
| &base_addr); |
| if (result == PS_OK) |
| { |
| /* Extend the value to 64 bits. Here it's assumed that |
| a "long" and a "void *" are the same. */ |
| (*base) = (void *) (long) base_addr; |
| } |
| return result; |
| } |
| else |
| { |
| |
| /* FIXME: ezannoni-2003-07-09 see comment above about include |
| file order. We could be getting bogus values for these two. */ |
| gdb_assert (FS < ELF_NGREG); |
| gdb_assert (GS < ELF_NGREG); |
| switch (idx) |
| { |
| case FS: |
| { |
| unsigned long fs; |
| errno = 0; |
| fs = ptrace (PTRACE_PEEKUSER, lwpid, |
| offsetof (struct user_regs_struct, fs_base), 0); |
| if (errno == 0) |
| { |
| *base = (void *) fs; |
| return PS_OK; |
| } |
| } |
| |
| break; |
| |
| case GS: |
| { |
| unsigned long gs; |
| errno = 0; |
| gs = ptrace (PTRACE_PEEKUSER, lwpid, |
| offsetof (struct user_regs_struct, gs_base), 0); |
| if (errno == 0) |
| { |
| *base = (void *) gs; |
| return PS_OK; |
| } |
| } |
| break; |
| |
| default: /* Should not happen. */ |
| return PS_BADADDR; |
| } |
| } |
| return PS_ERR; /* ptrace failed. */ |
| } |
| |
| |
| /* Convert a ptrace/host siginfo object, into/from the siginfo in the |
| layout of the inferiors' architecture. Returns true if any |
| conversion was done; false otherwise. If DIRECTION is 1, then copy |
| from INF to PTRACE. If DIRECTION is 0, copy from PTRACE to |
| INF. */ |
| |
| bool |
| amd64_linux_nat_target::low_siginfo_fixup (siginfo_t *ptrace, |
| gdb_byte *inf, |
| int direction) |
| { |
| struct gdbarch *gdbarch = get_frame_arch (get_current_frame ()); |
| |
| /* Is the inferior 32-bit? If so, then do fixup the siginfo |
| object. */ |
| if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32) |
| return amd64_linux_siginfo_fixup_common (ptrace, inf, direction, |
| FIXUP_32); |
| /* No fixup for native x32 GDB. */ |
| else if (gdbarch_addr_bit (gdbarch) == 32 && sizeof (void *) == 8) |
| return amd64_linux_siginfo_fixup_common (ptrace, inf, direction, |
| FIXUP_X32); |
| else |
| return false; |
| } |
| |
| void _initialize_amd64_linux_nat (); |
| void |
| _initialize_amd64_linux_nat () |
| { |
| amd64_native_gregset32_reg_offset = amd64_linux_gregset32_reg_offset; |
| amd64_native_gregset32_num_regs = I386_LINUX_NUM_REGS; |
| amd64_native_gregset64_reg_offset = amd64_linux_gregset_reg_offset; |
| amd64_native_gregset64_num_regs = AMD64_LINUX_NUM_REGS; |
| |
| gdb_assert (ARRAY_SIZE (amd64_linux_gregset32_reg_offset) |
| == amd64_native_gregset32_num_regs); |
| |
| linux_target = &the_amd64_linux_nat_target; |
| |
| /* Add the target. */ |
| add_inf_child_target (linux_target); |
| } |