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- /* Target-dependent code for GNU/Linux on Nios II.
- Copyright (C) 2012-2022 Free Software Foundation, Inc.
- Contributed by Mentor Graphics, 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 "osabi.h"
- #include "solib-svr4.h"
- #include "trad-frame.h"
- #include "tramp-frame.h"
- #include "symtab.h"
- #include "regset.h"
- #include "regcache.h"
- #include "linux-tdep.h"
- #include "glibc-tdep.h"
- #include "nios2-tdep.h"
- #include "gdbarch.h"
- /* Core file and register set support. */
- /* Map from the normal register enumeration order to the order that
- registers appear in core files, which corresponds to the order
- of the register slots in the kernel's struct pt_regs. */
- static const int reg_offsets[NIOS2_NUM_REGS] =
- {
- -1, 8, 9, 10, 11, 12, 13, 14, /* r0 - r7 */
- 0, 1, 2, 3, 4, 5, 6, 7, /* r8 - r15 */
- 23, 24, 25, 26, 27, 28, 29, 30, /* r16 - r23 */
- -1, -1, 19, 18, 17, 21, -1, 16, /* et bt gp sp fp ea sstatus ra */
- 21, /* pc */
- -1, 20, -1, -1, -1, -1, -1, -1, /* status estatus ... */
- -1, -1, -1, -1, -1, -1, -1, -1
- };
- /* General register set size. Should match sizeof (struct pt_regs) +
- sizeof (struct switch_stack) from the NIOS2 Linux kernel patch. */
- #define NIOS2_GREGS_SIZE (4 * 34)
- /* Implement the supply_regset hook for core files. */
- static void
- nios2_supply_gregset (const struct regset *regset,
- struct regcache *regcache,
- int regnum, const void *gregs_buf, size_t len)
- {
- const gdb_byte *gregs = (const gdb_byte *) gregs_buf;
- int regno;
- static const gdb_byte zero_buf[4] = {0, 0, 0, 0};
- for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++)
- if (regnum == -1 || regnum == regno)
- {
- if (reg_offsets[regno] != -1)
- regcache->raw_supply (regno, gregs + 4 * reg_offsets[regno]);
- else
- regcache->raw_supply (regno, zero_buf);
- }
- }
- /* Implement the collect_regset hook for core files. */
- static void
- nios2_collect_gregset (const struct regset *regset,
- const struct regcache *regcache,
- int regnum, void *gregs_buf, size_t len)
- {
- gdb_byte *gregs = (gdb_byte *) gregs_buf;
- int regno;
- for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++)
- if (regnum == -1 || regnum == regno)
- {
- if (reg_offsets[regno] != -1)
- regcache->raw_collect (regno, gregs + 4 * reg_offsets[regno]);
- }
- }
- static const struct regset nios2_core_regset =
- {
- NULL,
- nios2_supply_gregset,
- nios2_collect_gregset
- };
- /* Iterate over core file register note sections. */
- static void
- nios2_iterate_over_regset_sections (struct gdbarch *gdbarch,
- iterate_over_regset_sections_cb *cb,
- void *cb_data,
- const struct regcache *regcache)
- {
- cb (".reg", NIOS2_GREGS_SIZE, NIOS2_GREGS_SIZE, &nios2_core_regset, NULL,
- cb_data);
- }
- /* Initialize a trad-frame cache corresponding to the tramp-frame.
- FUNC is the address of the instruction TRAMP[0] in memory.
- This ABI is not documented. It corresponds to rt_setup_ucontext in
- the kernel arch/nios2/kernel/signal.c file.
- The key points are:
- - The kernel creates a trampoline at the hard-wired address 0x1044.
- - The stack pointer points to an object of type struct rt_sigframe.
- The definition of this structure is not exported from the kernel.
- The register save area is located at offset 152 bytes (as determined
- by inspection of the stack contents in the debugger), and the
- registers are saved as r1-r23, ra, fp, gp, ea, sp.
- This interface was implemented with kernel version 3.19 (the first
- official mainline kernel). Older unofficial kernel versions used
- incompatible conventions; we do not support those here. */
- #define NIOS2_SIGRETURN_TRAMP_ADDR 0x1044
- #define NIOS2_SIGRETURN_REGSAVE_OFFSET 152
- static void
- nios2_linux_rt_sigreturn_init (const struct tramp_frame *self,
- struct frame_info *next_frame,
- struct trad_frame_cache *this_cache,
- CORE_ADDR func)
- {
- CORE_ADDR sp = get_frame_register_unsigned (next_frame, NIOS2_SP_REGNUM);
- CORE_ADDR base = sp + NIOS2_SIGRETURN_REGSAVE_OFFSET;
- int i;
- for (i = 0; i < 23; i++)
- trad_frame_set_reg_addr (this_cache, i + 1, base + i * 4);
- trad_frame_set_reg_addr (this_cache, NIOS2_RA_REGNUM, base + 23 * 4);
- trad_frame_set_reg_addr (this_cache, NIOS2_FP_REGNUM, base + 24 * 4);
- trad_frame_set_reg_addr (this_cache, NIOS2_GP_REGNUM, base + 25 * 4);
- trad_frame_set_reg_addr (this_cache, NIOS2_PC_REGNUM, base + 27 * 4);
- trad_frame_set_reg_addr (this_cache, NIOS2_SP_REGNUM, base + 28 * 4);
- /* Save a frame ID. */
- trad_frame_set_id (this_cache, frame_id_build (base, func));
- }
- /* Trampoline for sigreturn. This has the form
- movi r2, __NR_rt_sigreturn
- trap 0
- appropriately encoded for R1 or R2. */
- static struct tramp_frame nios2_r1_linux_rt_sigreturn_tramp_frame =
- {
- SIGTRAMP_FRAME,
- 4,
- {
- { MATCH_R1_MOVI | SET_IW_I_B (2) | SET_IW_I_IMM16 (139), ULONGEST_MAX },
- { MATCH_R1_TRAP | SET_IW_R_IMM5 (0), ULONGEST_MAX},
- { TRAMP_SENTINEL_INSN }
- },
- nios2_linux_rt_sigreturn_init
- };
- static struct tramp_frame nios2_r2_linux_rt_sigreturn_tramp_frame =
- {
- SIGTRAMP_FRAME,
- 4,
- {
- { MATCH_R2_MOVI | SET_IW_F2I16_B (2) | SET_IW_F2I16_IMM16 (139), ULONGEST_MAX },
- { MATCH_R2_TRAP | SET_IW_X2L5_IMM5 (0), ULONGEST_MAX},
- { TRAMP_SENTINEL_INSN }
- },
- nios2_linux_rt_sigreturn_init
- };
- /* When FRAME is at a syscall instruction, return the PC of the next
- instruction to be executed. */
- static CORE_ADDR
- nios2_linux_syscall_next_pc (struct frame_info *frame,
- const struct nios2_opcode *op)
- {
- CORE_ADDR pc = get_frame_pc (frame);
- ULONGEST syscall_nr = get_frame_register_unsigned (frame, NIOS2_R2_REGNUM);
- /* If we are about to make a sigreturn syscall, use the unwinder to
- decode the signal frame. */
- if (syscall_nr == 139 /* rt_sigreturn */)
- return frame_unwind_caller_pc (frame);
- return pc + op->size;
- }
- /* Return true if PC is a kernel helper, a function mapped by the kernel
- into user space on an unwritable page. Currently the only such function
- is __kuser_cmpxchg at 0x1004. See arch/nios2/kernel/entry.S in the Linux
- kernel sources and sysdeps/unix/sysv/linux/nios2/atomic-machine.h in
- GLIBC. */
- static bool
- nios2_linux_is_kernel_helper (CORE_ADDR pc)
- {
- return pc == 0x1004;
- }
- /* Hook function for gdbarch_register_osabi. */
- static void
- nios2_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
- {
- nios2_gdbarch_tdep *tdep = (nios2_gdbarch_tdep *) gdbarch_tdep (gdbarch);
- linux_init_abi (info, gdbarch, 0);
- /* Shared library handling. */
- set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
- set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
- set_solib_svr4_fetch_link_map_offsets (gdbarch,
- linux_ilp32_fetch_link_map_offsets);
- /* Enable TLS support. */
- set_gdbarch_fetch_tls_load_module_address (gdbarch,
- svr4_fetch_objfile_link_map);
- /* Core file support. */
- set_gdbarch_iterate_over_regset_sections
- (gdbarch, nios2_iterate_over_regset_sections);
- /* Linux signal frame unwinders. */
- if (gdbarch_bfd_arch_info (gdbarch)->mach == bfd_mach_nios2r2)
- tramp_frame_prepend_unwinder (gdbarch,
- &nios2_r2_linux_rt_sigreturn_tramp_frame);
- else
- tramp_frame_prepend_unwinder (gdbarch,
- &nios2_r1_linux_rt_sigreturn_tramp_frame);
- tdep->syscall_next_pc = nios2_linux_syscall_next_pc;
- tdep->is_kernel_helper = nios2_linux_is_kernel_helper;
- /* Index of target address word in glibc jmp_buf. */
- tdep->jb_pc = 10;
- }
- void _initialize_nios2_linux_tdep ();
- void
- _initialize_nios2_linux_tdep ()
- {
- const struct bfd_arch_info *arch_info;
- for (arch_info = bfd_lookup_arch (bfd_arch_nios2, 0);
- arch_info != NULL;
- arch_info = arch_info->next)
- gdbarch_register_osabi (bfd_arch_nios2, arch_info->mach,
- GDB_OSABI_LINUX, nios2_linux_init_abi);
- }
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