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- /* Target dependent code for the remote server for GNU/Linux ARC.
- Copyright 2020-2022 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 "server.h"
- #include "regdef.h"
- #include "linux-low.h"
- #include "tdesc.h"
- #include "arch/arc.h"
- #include <linux/elf.h>
- #include <arpa/inet.h>
- /* Linux starting with 4.12 supports NT_ARC_V2 note type, which adds R30,
- R58 and R59 registers. */
- #ifdef NT_ARC_V2
- #define ARC_HAS_V2_REGSET
- #endif
- /* The encoding of the instruction "TRAP_S 1" (endianness agnostic). */
- #define TRAP_S_1_OPCODE 0x783e
- #define TRAP_S_1_SIZE 2
- /* Using a mere "uint16_t arc_linux_traps_s = TRAP_S_1_OPCODE" would
- work as well, because the endianness will end up correctly when
- the code is compiled for the same endianness as the target (see
- the notes for "low_breakpoint_at" in this file). However, this
- illustrates how the __BIG_ENDIAN__ macro can be used to make
- easy-to-understand codes. */
- #if defined(__BIG_ENDIAN__)
- /* 0x78, 0x3e. */
- static gdb_byte arc_linux_trap_s[TRAP_S_1_SIZE]
- = {TRAP_S_1_OPCODE >> 8, TRAP_S_1_OPCODE & 0xFF};
- #else
- /* 0x3e, 0x78. */
- static gdb_byte arc_linux_trap_s[TRAP_S_1_SIZE]
- = {TRAP_S_1_OPCODE && 0xFF, TRAP_S_1_OPCODE >> 8};
- #endif
- /* Linux target op definitions for the ARC architecture.
- Note for future: in case of adding the protected method low_get_next_pcs(),
- the public method supports_software_single_step() should be added to return
- "true". */
- class arc_target : public linux_process_target
- {
- public:
- const regs_info *get_regs_info () override;
- const gdb_byte *sw_breakpoint_from_kind (int kind, int *size) override;
- protected:
- void low_arch_setup () override;
- bool low_cannot_fetch_register (int regno) override;
- bool low_cannot_store_register (int regno) override;
- bool low_supports_breakpoints () override;
- CORE_ADDR low_get_pc (regcache *regcache) override;
- void low_set_pc (regcache *regcache, CORE_ADDR newpc) override;
- bool low_breakpoint_at (CORE_ADDR where) override;
- };
- /* The singleton target ops object. */
- static arc_target the_arc_target;
- bool
- arc_target::low_supports_breakpoints ()
- {
- return true;
- }
- CORE_ADDR
- arc_target::low_get_pc (regcache *regcache)
- {
- return linux_get_pc_32bit (regcache);
- }
- void
- arc_target::low_set_pc (regcache *regcache, CORE_ADDR pc)
- {
- linux_set_pc_32bit (regcache, pc);
- }
- static const struct target_desc *
- arc_linux_read_description (void)
- {
- #ifdef __ARC700__
- arc_arch_features features (4, ARC_ISA_ARCV1);
- #else
- arc_arch_features features (4, ARC_ISA_ARCV2);
- #endif
- target_desc_up tdesc = arc_create_target_description (features);
- static const char *expedite_regs[] = { "sp", "status32", nullptr };
- init_target_desc (tdesc.get (), expedite_regs);
- return tdesc.release ();
- }
- void
- arc_target::low_arch_setup ()
- {
- current_process ()->tdesc = arc_linux_read_description ();
- }
- bool
- arc_target::low_cannot_fetch_register (int regno)
- {
- return (regno >= current_process ()->tdesc->reg_defs.size ());
- }
- bool
- arc_target::low_cannot_store_register (int regno)
- {
- return (regno >= current_process ()->tdesc->reg_defs.size ());
- }
- /* This works for both endianness. Below you see an illustration of how
- the "trap_s 1" instruction encoded for both endianness in the memory
- will end up as the TRAP_S_1_OPCODE constant:
- BE: 0x78 0x3e --> at INSN addr: 0x78 0x3e --> INSN = 0x783e
- LE: 0x3e 0x78 --> at INSN addr: 0x3e 0x78 --> INSN = 0x783e
- One can employ "memcmp()" for comparing the arrays too. */
- bool
- arc_target::low_breakpoint_at (CORE_ADDR where)
- {
- uint16_t insn;
- /* "the_target" global variable is the current object at hand. */
- this->read_memory (where, (gdb_byte *) &insn, TRAP_S_1_SIZE);
- return (insn == TRAP_S_1_OPCODE);
- }
- /* PTRACE_GETREGSET/NT_PRSTATUS and PTRACE_SETREGSET/NT_PRSTATUS work with
- regsets in a struct, "user_regs_struct", defined in the
- linux/arch/arc/include/uapi/asm/ptrace.h header. This code supports
- ARC Linux ABI v3 and v4. */
- /* Populate a ptrace NT_PRSTATUS regset from a regcache.
- This appears to be a unique approach to populating the buffer, but
- being name, rather than offset based, it is robust to future API
- changes, as there is no need to create a regmap of registers in the
- user_regs_struct. */
- static void
- arc_fill_gregset (struct regcache *regcache, void *buf)
- {
- struct user_regs_struct *regbuf = (struct user_regs_struct *) buf;
- /* Core registers. */
- collect_register_by_name (regcache, "r0", &(regbuf->scratch.r0));
- collect_register_by_name (regcache, "r1", &(regbuf->scratch.r1));
- collect_register_by_name (regcache, "r2", &(regbuf->scratch.r2));
- collect_register_by_name (regcache, "r3", &(regbuf->scratch.r3));
- collect_register_by_name (regcache, "r4", &(regbuf->scratch.r4));
- collect_register_by_name (regcache, "r5", &(regbuf->scratch.r5));
- collect_register_by_name (regcache, "r6", &(regbuf->scratch.r6));
- collect_register_by_name (regcache, "r7", &(regbuf->scratch.r7));
- collect_register_by_name (regcache, "r8", &(regbuf->scratch.r8));
- collect_register_by_name (regcache, "r9", &(regbuf->scratch.r9));
- collect_register_by_name (regcache, "r10", &(regbuf->scratch.r10));
- collect_register_by_name (regcache, "r11", &(regbuf->scratch.r11));
- collect_register_by_name (regcache, "r12", &(regbuf->scratch.r12));
- collect_register_by_name (regcache, "r13", &(regbuf->callee.r13));
- collect_register_by_name (regcache, "r14", &(regbuf->callee.r14));
- collect_register_by_name (regcache, "r15", &(regbuf->callee.r15));
- collect_register_by_name (regcache, "r16", &(regbuf->callee.r16));
- collect_register_by_name (regcache, "r17", &(regbuf->callee.r17));
- collect_register_by_name (regcache, "r18", &(regbuf->callee.r18));
- collect_register_by_name (regcache, "r19", &(regbuf->callee.r19));
- collect_register_by_name (regcache, "r20", &(regbuf->callee.r20));
- collect_register_by_name (regcache, "r21", &(regbuf->callee.r21));
- collect_register_by_name (regcache, "r22", &(regbuf->callee.r22));
- collect_register_by_name (regcache, "r23", &(regbuf->callee.r23));
- collect_register_by_name (regcache, "r24", &(regbuf->callee.r24));
- collect_register_by_name (regcache, "r25", &(regbuf->callee.r25));
- collect_register_by_name (regcache, "gp", &(regbuf->scratch.gp));
- collect_register_by_name (regcache, "fp", &(regbuf->scratch.fp));
- collect_register_by_name (regcache, "sp", &(regbuf->scratch.sp));
- collect_register_by_name (regcache, "blink", &(regbuf->scratch.blink));
- /* Loop registers. */
- collect_register_by_name (regcache, "lp_count", &(regbuf->scratch.lp_count));
- collect_register_by_name (regcache, "lp_start", &(regbuf->scratch.lp_start));
- collect_register_by_name (regcache, "lp_end", &(regbuf->scratch.lp_end));
- /* The current "pc" value must be written to "eret" (exception return
- address) register, because that is the address that the kernel code
- will jump back to after a breakpoint exception has been raised.
- The "pc_stop" value is ignored by the genregs_set() in
- linux/arch/arc/kernel/ptrace.c. */
- collect_register_by_name (regcache, "pc", &(regbuf->scratch.ret));
- /* Currently ARC Linux ptrace doesn't allow writes to status32 because
- some of its bits are kernel mode-only and shoudn't be writable from
- user-space. Writing status32 from debugger could be useful, though,
- so ability to write non-priviliged bits will be added to kernel
- sooner or later. */
- /* BTA. */
- collect_register_by_name (regcache, "bta", &(regbuf->scratch.bta));
- }
- /* Populate a regcache from a ptrace NT_PRSTATUS regset. */
- static void
- arc_store_gregset (struct regcache *regcache, const void *buf)
- {
- const struct user_regs_struct *regbuf = (const struct user_regs_struct *) buf;
- /* Core registers. */
- supply_register_by_name (regcache, "r0", &(regbuf->scratch.r0));
- supply_register_by_name (regcache, "r1", &(regbuf->scratch.r1));
- supply_register_by_name (regcache, "r2", &(regbuf->scratch.r2));
- supply_register_by_name (regcache, "r3", &(regbuf->scratch.r3));
- supply_register_by_name (regcache, "r4", &(regbuf->scratch.r4));
- supply_register_by_name (regcache, "r5", &(regbuf->scratch.r5));
- supply_register_by_name (regcache, "r6", &(regbuf->scratch.r6));
- supply_register_by_name (regcache, "r7", &(regbuf->scratch.r7));
- supply_register_by_name (regcache, "r8", &(regbuf->scratch.r8));
- supply_register_by_name (regcache, "r9", &(regbuf->scratch.r9));
- supply_register_by_name (regcache, "r10", &(regbuf->scratch.r10));
- supply_register_by_name (regcache, "r11", &(regbuf->scratch.r11));
- supply_register_by_name (regcache, "r12", &(regbuf->scratch.r12));
- supply_register_by_name (regcache, "r13", &(regbuf->callee.r13));
- supply_register_by_name (regcache, "r14", &(regbuf->callee.r14));
- supply_register_by_name (regcache, "r15", &(regbuf->callee.r15));
- supply_register_by_name (regcache, "r16", &(regbuf->callee.r16));
- supply_register_by_name (regcache, "r17", &(regbuf->callee.r17));
- supply_register_by_name (regcache, "r18", &(regbuf->callee.r18));
- supply_register_by_name (regcache, "r19", &(regbuf->callee.r19));
- supply_register_by_name (regcache, "r20", &(regbuf->callee.r20));
- supply_register_by_name (regcache, "r21", &(regbuf->callee.r21));
- supply_register_by_name (regcache, "r22", &(regbuf->callee.r22));
- supply_register_by_name (regcache, "r23", &(regbuf->callee.r23));
- supply_register_by_name (regcache, "r24", &(regbuf->callee.r24));
- supply_register_by_name (regcache, "r25", &(regbuf->callee.r25));
- supply_register_by_name (regcache, "gp", &(regbuf->scratch.gp));
- supply_register_by_name (regcache, "fp", &(regbuf->scratch.fp));
- supply_register_by_name (regcache, "sp", &(regbuf->scratch.sp));
- supply_register_by_name (regcache, "blink", &(regbuf->scratch.blink));
- /* Loop registers. */
- supply_register_by_name (regcache, "lp_count", &(regbuf->scratch.lp_count));
- supply_register_by_name (regcache, "lp_start", &(regbuf->scratch.lp_start));
- supply_register_by_name (regcache, "lp_end", &(regbuf->scratch.lp_end));
- /* The genregs_get() in linux/arch/arc/kernel/ptrace.c populates the
- pseudo register "stop_pc" with the "efa" (exception fault address)
- register. This was deemed necessary, because the breakpoint
- instruction, "trap_s 1", is a committing one; i.e. the "eret"
- (exception return address) register will be pointing to the next
- instruction, while "efa" points to the address that raised the
- breakpoint. */
- supply_register_by_name (regcache, "pc", &(regbuf->stop_pc));
- unsigned long pcl = regbuf->stop_pc & ~3L;
- supply_register_by_name (regcache, "pcl", &pcl);
- /* Other auxilliary registers. */
- supply_register_by_name (regcache, "status32", &(regbuf->scratch.status32));
- /* BTA. */
- supply_register_by_name (regcache, "bta", &(regbuf->scratch.bta));
- }
- #ifdef ARC_HAS_V2_REGSET
- /* Look through a regcache's TDESC for a register named NAME.
- If found, return true; false, otherwise. */
- static bool
- is_reg_name_available_p (const struct target_desc *tdesc,
- const char *name)
- {
- for (const gdb::reg ® : tdesc->reg_defs)
- if (strcmp (name, reg.name) == 0)
- return true;
- return false;
- }
- /* Copy registers from regcache to user_regs_arcv2. */
- static void
- arc_fill_v2_regset (struct regcache *regcache, void *buf)
- {
- struct user_regs_arcv2 *regbuf = (struct user_regs_arcv2 *) buf;
- if (is_reg_name_available_p (regcache->tdesc, "r30"))
- collect_register_by_name (regcache, "r30", &(regbuf->r30));
- if (is_reg_name_available_p (regcache->tdesc, "r58"))
- collect_register_by_name (regcache, "r58", &(regbuf->r58));
- if (is_reg_name_available_p (regcache->tdesc, "r59"))
- collect_register_by_name (regcache, "r59", &(regbuf->r59));
- }
- /* Copy registers from user_regs_arcv2 to regcache. */
- static void
- arc_store_v2_regset (struct regcache *regcache, const void *buf)
- {
- struct user_regs_arcv2 *regbuf = (struct user_regs_arcv2 *) buf;
- if (is_reg_name_available_p (regcache->tdesc, "r30"))
- supply_register_by_name (regcache, "r30", &(regbuf->r30));
- if (is_reg_name_available_p (regcache->tdesc, "r58"))
- supply_register_by_name (regcache, "r58", &(regbuf->r58));
- if (is_reg_name_available_p (regcache->tdesc, "r59"))
- supply_register_by_name (regcache, "r59", &(regbuf->r59));
- }
- #endif
- /* Fetch the thread-local storage pointer for libthread_db. Note that
- this function is not called from GDB, but is called from libthread_db.
- This is the same function as for other architectures, for example in
- linux-arm-low.c. */
- ps_err_e
- ps_get_thread_area (struct ps_prochandle *ph, lwpid_t lwpid,
- int idx, void **base)
- {
- if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, nullptr, base) != 0)
- return PS_ERR;
- /* IDX is the bias from the thread pointer to the beginning of the
- thread descriptor. It has to be subtracted due to implementation
- quirks in libthread_db. */
- *base = (void *) ((char *) *base - idx);
- return PS_OK;
- }
- static struct regset_info arc_regsets[] =
- {
- { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_PRSTATUS,
- sizeof (struct user_regs_struct), GENERAL_REGS,
- arc_fill_gregset, arc_store_gregset
- },
- #ifdef ARC_HAS_V2_REGSET
- { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_ARC_V2,
- sizeof (struct user_regs_arcv2), GENERAL_REGS,
- arc_fill_v2_regset, arc_store_v2_regset
- },
- #endif
- NULL_REGSET
- };
- static struct regsets_info arc_regsets_info =
- {
- arc_regsets, /* regsets */
- 0, /* num_regsets */
- nullptr, /* disabled regsets */
- };
- static struct regs_info arc_regs_info =
- {
- nullptr, /* regset_bitmap */
- nullptr, /* usrregs */
- &arc_regsets_info
- };
- const regs_info *
- arc_target::get_regs_info ()
- {
- return &arc_regs_info;
- }
- /* One of the methods necessary for Z0 packet support. */
- const gdb_byte *
- arc_target::sw_breakpoint_from_kind (int kind, int *size)
- {
- gdb_assert (kind == TRAP_S_1_SIZE);
- *size = kind;
- return arc_linux_trap_s;
- }
- /* The linux target ops object. */
- linux_process_target *the_linux_target = &the_arc_target;
- void
- initialize_low_arch (void)
- {
- initialize_regsets_info (&arc_regsets_info);
- }
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