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263 lines
8.4 KiB
C
263 lines
8.4 KiB
C
/* Target-dependent code for GNU/Linux on Nios II.
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Copyright (C) 2012-2020 Free Software Foundation, Inc.
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Contributed by Mentor Graphics, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "frame.h"
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#include "osabi.h"
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#include "solib-svr4.h"
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#include "trad-frame.h"
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#include "tramp-frame.h"
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#include "symtab.h"
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#include "regset.h"
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#include "regcache.h"
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#include "linux-tdep.h"
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#include "glibc-tdep.h"
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#include "nios2-tdep.h"
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#include "gdbarch.h"
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/* Core file and register set support. */
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/* Map from the normal register enumeration order to the order that
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registers appear in core files, which corresponds to the order
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of the register slots in the kernel's struct pt_regs. */
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static const int reg_offsets[NIOS2_NUM_REGS] =
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{
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-1, 8, 9, 10, 11, 12, 13, 14, /* r0 - r7 */
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0, 1, 2, 3, 4, 5, 6, 7, /* r8 - r15 */
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23, 24, 25, 26, 27, 28, 29, 30, /* r16 - r23 */
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-1, -1, 19, 18, 17, 21, -1, 16, /* et bt gp sp fp ea sstatus ra */
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21, /* pc */
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-1, 20, -1, -1, -1, -1, -1, -1, /* status estatus ... */
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-1, -1, -1, -1, -1, -1, -1, -1
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};
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/* General register set size. Should match sizeof (struct pt_regs) +
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sizeof (struct switch_stack) from the NIOS2 Linux kernel patch. */
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#define NIOS2_GREGS_SIZE (4 * 34)
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/* Implement the supply_regset hook for core files. */
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static void
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nios2_supply_gregset (const struct regset *regset,
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struct regcache *regcache,
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int regnum, const void *gregs_buf, size_t len)
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{
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const gdb_byte *gregs = (const gdb_byte *) gregs_buf;
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int regno;
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static const gdb_byte zero_buf[4] = {0, 0, 0, 0};
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for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++)
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if (regnum == -1 || regnum == regno)
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{
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if (reg_offsets[regno] != -1)
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regcache->raw_supply (regno, gregs + 4 * reg_offsets[regno]);
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else
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regcache->raw_supply (regno, zero_buf);
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}
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}
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/* Implement the collect_regset hook for core files. */
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static void
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nios2_collect_gregset (const struct regset *regset,
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const struct regcache *regcache,
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int regnum, void *gregs_buf, size_t len)
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{
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gdb_byte *gregs = (gdb_byte *) gregs_buf;
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int regno;
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for (regno = NIOS2_Z_REGNUM; regno <= NIOS2_MPUACC_REGNUM; regno++)
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if (regnum == -1 || regnum == regno)
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{
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if (reg_offsets[regno] != -1)
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regcache->raw_collect (regno, gregs + 4 * reg_offsets[regno]);
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}
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}
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static const struct regset nios2_core_regset =
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{
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NULL,
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nios2_supply_gregset,
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nios2_collect_gregset
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};
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/* Iterate over core file register note sections. */
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static void
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nios2_iterate_over_regset_sections (struct gdbarch *gdbarch,
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iterate_over_regset_sections_cb *cb,
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void *cb_data,
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const struct regcache *regcache)
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{
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cb (".reg", NIOS2_GREGS_SIZE, NIOS2_GREGS_SIZE, &nios2_core_regset, NULL,
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cb_data);
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}
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/* Initialize a trad-frame cache corresponding to the tramp-frame.
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FUNC is the address of the instruction TRAMP[0] in memory.
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This ABI is not documented. It corresponds to rt_setup_ucontext in
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the kernel arch/nios2/kernel/signal.c file.
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The key points are:
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- The kernel creates a trampoline at the hard-wired address 0x1044.
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- The stack pointer points to an object of type struct rt_sigframe.
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The definition of this structure is not exported from the kernel.
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The register save area is located at offset 152 bytes (as determined
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by inspection of the stack contents in the debugger), and the
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registers are saved as r1-r23, ra, fp, gp, ea, sp.
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This interface was implemented with kernel version 3.19 (the first
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official mainline kernel). Older unofficial kernel versions used
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incompatible conventions; we do not support those here. */
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#define NIOS2_SIGRETURN_TRAMP_ADDR 0x1044
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#define NIOS2_SIGRETURN_REGSAVE_OFFSET 152
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static void
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nios2_linux_rt_sigreturn_init (const struct tramp_frame *self,
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struct frame_info *next_frame,
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struct trad_frame_cache *this_cache,
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CORE_ADDR func)
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{
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CORE_ADDR sp = get_frame_register_unsigned (next_frame, NIOS2_SP_REGNUM);
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CORE_ADDR base = sp + NIOS2_SIGRETURN_REGSAVE_OFFSET;
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int i;
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for (i = 0; i < 23; i++)
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trad_frame_set_reg_addr (this_cache, i + 1, base + i * 4);
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trad_frame_set_reg_addr (this_cache, NIOS2_RA_REGNUM, base + 23 * 4);
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trad_frame_set_reg_addr (this_cache, NIOS2_FP_REGNUM, base + 24 * 4);
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trad_frame_set_reg_addr (this_cache, NIOS2_GP_REGNUM, base + 25 * 4);
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trad_frame_set_reg_addr (this_cache, NIOS2_PC_REGNUM, base + 27 * 4);
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trad_frame_set_reg_addr (this_cache, NIOS2_SP_REGNUM, base + 28 * 4);
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/* Save a frame ID. */
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trad_frame_set_id (this_cache, frame_id_build (base, func));
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}
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/* Trampoline for sigreturn. This has the form
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movi r2, __NR_rt_sigreturn
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trap 0
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appropriately encoded for R1 or R2. */
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static struct tramp_frame nios2_r1_linux_rt_sigreturn_tramp_frame =
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{
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SIGTRAMP_FRAME,
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4,
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{
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{ MATCH_R1_MOVI | SET_IW_I_B (2) | SET_IW_I_IMM16 (139), ULONGEST_MAX },
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{ MATCH_R1_TRAP | SET_IW_R_IMM5 (0), ULONGEST_MAX},
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{ TRAMP_SENTINEL_INSN }
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},
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nios2_linux_rt_sigreturn_init
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};
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static struct tramp_frame nios2_r2_linux_rt_sigreturn_tramp_frame =
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{
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SIGTRAMP_FRAME,
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4,
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{
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{ MATCH_R2_MOVI | SET_IW_F2I16_B (2) | SET_IW_F2I16_IMM16 (139), ULONGEST_MAX },
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{ MATCH_R2_TRAP | SET_IW_X2L5_IMM5 (0), ULONGEST_MAX},
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{ TRAMP_SENTINEL_INSN }
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},
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nios2_linux_rt_sigreturn_init
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};
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/* When FRAME is at a syscall instruction, return the PC of the next
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instruction to be executed. */
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static CORE_ADDR
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nios2_linux_syscall_next_pc (struct frame_info *frame,
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const struct nios2_opcode *op)
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{
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CORE_ADDR pc = get_frame_pc (frame);
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ULONGEST syscall_nr = get_frame_register_unsigned (frame, NIOS2_R2_REGNUM);
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/* If we are about to make a sigreturn syscall, use the unwinder to
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decode the signal frame. */
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if (syscall_nr == 139 /* rt_sigreturn */)
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return frame_unwind_caller_pc (frame);
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return pc + op->size;
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}
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/* Return true if PC is a kernel helper, a function mapped by the kernel
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into user space on an unwritable page. Currently the only such function
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is __kuser_cmpxchg at 0x1004. See arch/nios2/kernel/entry.S in the Linux
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kernel sources and sysdeps/unix/sysv/linux/nios2/atomic-machine.h in
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GLIBC. */
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static bool
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nios2_linux_is_kernel_helper (CORE_ADDR pc)
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{
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return pc == 0x1004;
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}
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/* Hook function for gdbarch_register_osabi. */
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static void
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nios2_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
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{
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struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
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linux_init_abi (info, gdbarch);
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/* Shared library handling. */
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set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
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set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
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set_solib_svr4_fetch_link_map_offsets (gdbarch,
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svr4_ilp32_fetch_link_map_offsets);
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/* Enable TLS support. */
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set_gdbarch_fetch_tls_load_module_address (gdbarch,
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svr4_fetch_objfile_link_map);
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/* Core file support. */
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set_gdbarch_iterate_over_regset_sections
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(gdbarch, nios2_iterate_over_regset_sections);
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/* Linux signal frame unwinders. */
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if (gdbarch_bfd_arch_info (gdbarch)->mach == bfd_mach_nios2r2)
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tramp_frame_prepend_unwinder (gdbarch,
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&nios2_r2_linux_rt_sigreturn_tramp_frame);
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else
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tramp_frame_prepend_unwinder (gdbarch,
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&nios2_r1_linux_rt_sigreturn_tramp_frame);
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tdep->syscall_next_pc = nios2_linux_syscall_next_pc;
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tdep->is_kernel_helper = nios2_linux_is_kernel_helper;
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/* Index of target address word in glibc jmp_buf. */
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tdep->jb_pc = 10;
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}
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void
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_initialize_nios2_linux_tdep (void)
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{
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const struct bfd_arch_info *arch_info;
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for (arch_info = bfd_lookup_arch (bfd_arch_nios2, 0);
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arch_info != NULL;
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arch_info = arch_info->next)
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gdbarch_register_osabi (bfd_arch_nios2, arch_info->mach,
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GDB_OSABI_LINUX, nios2_linux_init_abi);
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}
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