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/* Target-dependent code for GNU/Linux on RISC-V processors.
Copyright (C) 2018-2023 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 "riscv-tdep.h"
#include "osabi.h"
#include "glibc-tdep.h"
#include "linux-tdep.h"
#include "solib-svr4.h"
#include "regset.h"
#include "tramp-frame.h"
#include "trad-frame.h"
#include "gdbarch.h"
/* The following value is derived from __NR_rt_sigreturn in
<include/uapi/asm-generic/unistd.h> from the Linux source tree. */
#define RISCV_NR_rt_sigreturn 139
/* Define the general register mapping. The kernel puts the PC at offset 0,
gdb puts it at offset 32. Register x0 is always 0 and can be ignored.
Registers x1 to x31 are in the same place. */
static const struct regcache_map_entry riscv_linux_gregmap[] =
{
{ 1, RISCV_PC_REGNUM, 0 },
{ 31, RISCV_RA_REGNUM, 0 }, /* x1 to x31 */
{ 0 }
};
/* Define the FP register mapping. The kernel puts the 32 FP regs first, and
then FCSR. */
static const struct regcache_map_entry riscv_linux_fregmap[] =
{
{ 32, RISCV_FIRST_FP_REGNUM, 0 },
{ 1, RISCV_CSR_FCSR_REGNUM, 0 },
{ 0 }
};
/* Define the general register regset. */
static const struct regset riscv_linux_gregset =
{
riscv_linux_gregmap, riscv_supply_regset, regcache_collect_regset
};
/* Define the FP register regset. */
static const struct regset riscv_linux_fregset =
{
riscv_linux_fregmap, riscv_supply_regset, regcache_collect_regset
};
/* Define hook for core file support. */
static void
riscv_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
iterate_over_regset_sections_cb *cb,
void *cb_data,
const struct regcache *regcache)
{
cb (".reg", (32 * riscv_isa_xlen (gdbarch)), (32 * riscv_isa_xlen (gdbarch)),
&riscv_linux_gregset, NULL, cb_data);
/* The kernel is adding 8 bytes for FCSR. */
cb (".reg2", (32 * riscv_isa_flen (gdbarch)) + 8,
(32 * riscv_isa_flen (gdbarch)) + 8,
&riscv_linux_fregset, NULL, cb_data);
}
/* Signal trampoline support. */
static void riscv_linux_sigframe_init (const struct tramp_frame *self,
frame_info_ptr this_frame,
struct trad_frame_cache *this_cache,
CORE_ADDR func);
#define RISCV_INST_LI_A7_SIGRETURN 0x08b00893
#define RISCV_INST_ECALL 0x00000073
static const struct tramp_frame riscv_linux_sigframe = {
SIGTRAMP_FRAME,
4,
{
{ RISCV_INST_LI_A7_SIGRETURN, ULONGEST_MAX },
{ RISCV_INST_ECALL, ULONGEST_MAX },
{ TRAMP_SENTINEL_INSN }
},
riscv_linux_sigframe_init,
NULL
};
/* Runtime signal frames look like this:
struct rt_sigframe {
struct siginfo info;
struct ucontext uc;
};
struct ucontext {
unsigned long __uc_flags;
struct ucontext *uclink;
stack_t uc_stack;
sigset_t uc_sigmask;
char __glibc_reserved[1024 / 8 - sizeof (sigset_t)];
mcontext_t uc_mcontext;
}; */
#define SIGFRAME_SIGINFO_SIZE 128
#define UCONTEXT_MCONTEXT_OFFSET 176
static void
riscv_linux_sigframe_init (const struct tramp_frame *self,
frame_info_ptr this_frame,
struct trad_frame_cache *this_cache,
CORE_ADDR func)
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
int xlen = riscv_isa_xlen (gdbarch);
int flen = riscv_isa_flen (gdbarch);
CORE_ADDR frame_sp = get_frame_sp (this_frame);
CORE_ADDR mcontext_base;
CORE_ADDR regs_base;
mcontext_base = frame_sp + SIGFRAME_SIGINFO_SIZE + UCONTEXT_MCONTEXT_OFFSET;
/* Handle the integer registers. The first one is PC, followed by x1
through x31. */
regs_base = mcontext_base;
trad_frame_set_reg_addr (this_cache, RISCV_PC_REGNUM, regs_base);
for (int i = 1; i < 32; i++)
trad_frame_set_reg_addr (this_cache, RISCV_ZERO_REGNUM + i,
regs_base + (i * xlen));
/* Handle the FP registers. First comes the 32 FP registers, followed by
fcsr. */
regs_base += 32 * xlen;
for (int i = 0; i < 32; i++)
trad_frame_set_reg_addr (this_cache, RISCV_FIRST_FP_REGNUM + i,
regs_base + (i * flen));
regs_base += 32 * flen;
trad_frame_set_reg_addr (this_cache, RISCV_CSR_FCSR_REGNUM, regs_base);
/* Choice of the bottom of the sigframe is somewhat arbitrary. */
trad_frame_set_id (this_cache, frame_id_build (frame_sp, func));
}
/* When FRAME is at a syscall instruction (ECALL), return the PC of the next
instruction to be executed. */
static CORE_ADDR
riscv_linux_syscall_next_pc (frame_info_ptr frame)
{
const CORE_ADDR pc = get_frame_pc (frame);
const ULONGEST a7 = get_frame_register_unsigned (frame, RISCV_A7_REGNUM);
if (a7 == RISCV_NR_rt_sigreturn)
return frame_unwind_caller_pc (frame);
return pc + 4 /* Length of the ECALL insn. */;
}
/* Initialize RISC-V Linux ABI info. */
static void
riscv_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
riscv_gdbarch_tdep *tdep = gdbarch_tdep<riscv_gdbarch_tdep> (gdbarch);
linux_init_abi (info, gdbarch, 0);
set_gdbarch_software_single_step (gdbarch, riscv_software_single_step);
set_solib_svr4_fetch_link_map_offsets (gdbarch,
(riscv_isa_xlen (gdbarch) == 4
? linux_ilp32_fetch_link_map_offsets
: linux_lp64_fetch_link_map_offsets));
/* GNU/Linux uses SVR4-style shared libraries. */
set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
/* GNU/Linux uses the dynamic linker included in the GNU C Library. */
set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
/* Enable TLS support. */
set_gdbarch_fetch_tls_load_module_address (gdbarch,
svr4_fetch_objfile_link_map);
set_gdbarch_iterate_over_regset_sections
(gdbarch, riscv_linux_iterate_over_regset_sections);
tramp_frame_prepend_unwinder (gdbarch, &riscv_linux_sigframe);
tdep->syscall_next_pc = riscv_linux_syscall_next_pc;
}
/* Initialize RISC-V Linux target support. */
void _initialize_riscv_linux_tdep ();
void
_initialize_riscv_linux_tdep ()
{
gdbarch_register_osabi (bfd_arch_riscv, 0, GDB_OSABI_LINUX,
riscv_linux_init_abi);
}
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