binutils-gdb/gdb/riscv-none-tdep.c

174 lines
5.2 KiB
C
Raw Normal View History

/* Copyright (C) 2020-2022 Free Software Foundation, Inc.
gdb/riscv: introduce bare metal core dump support This commit adds the ability for bare metal RISC-V target to generate core files from within GDB. The intended use case is that a user will connect to a remote bare metal target, debug up to some error condition, then generate a core file in the normal way using: (gdb) generate-core-file This core file can then be used to revisit the state of the remote target without having to reconnect to the remote target. The core file creation code is split between two new files. In elf-none-tdep.c is code for any architecture with the none ABI (i.e. bare metal) when the BFD library is built with ELF support. In riscv-none-tdep.c are the RISC-V specific parts. This is where the regset and regcache_map_entry structures are defined that control how registers are laid out in the core file. As this file could (in theory at least) be used for a non-ELF bare metal RISC-V target, the calls into elf-none-tdep.c are guarded with '#ifdef HAVE_ELF'. Currently for RISC-V only the x-regs and f-regs (if present) are written out. In future commits I plan to add support for writing out the RISC-V CSRs. The core dump format is based around generating an ELF containing sections for the writable regions of memory that a user could be using. Which regions are dumped rely on GDB's existing common core dumping code, GDB will attempt to figure out the stack and heap as well as copying out writable data sections as identified by the original ELF. Register information is added to the core dump using notes, just as it is for Linux of FreeBSD core dumps. The note types used consist of the 3 basic types you would expect in a OS based core dump, NT_PRPSINFO, NT_PRSTATUS, NT_FPREGSET. The layout of these notes differs slightly (due to field sizes) between RV32 and RV64. Below I describe the data layout for each note. In all cases, all padding fields should be set to zero. Note NT_PRPSINFO is optional. Its data layout is: struct prpsinfo32_t /* For RV32. */ { uint8_t padding[32]; char fname[16]; char psargs[80]; } struct prpsinfo64_t /* For RV64. */ { uint8_t padding[40]; char fname[16]; char psargs[80]; } Field 'fname' - null terminated string consisting of the basename of (up to the fist 15 characters of) the executable. Any additional space should be set to zero. If there's no executable name then this field can be set to all zero. Field 'psargs' - a null terminated string up to 80 characters in length. Any additional space should be filled with zero. This field contains the full executable path and any arguments passed to the executable. If there's nothing sensible to write in this field then fill it with zero. Note NT_PRSTATUS is required, its data layout is: struct prstatus32_t /* For RV32. */ { uint8_t padding_1[12]; uint16_t sig; uint8_t padding_2[10]; uint32_t thread_id; uint8_t padding_3[44]; uint32_t x_regs[32]; uint8_t padding_4[4]; } struct prstatus64_t /* For RV64. */ { uint8_t padding_1[12]; uint16_t sig; uint8_t padding_2[18]; uint32_t thread_id; uint8_t padding_3[76]; uint64_t x_regs[32]; uint8_t padding_4[4]; } Field 'sig' - the signal that stopped this thread. It's implementation defined what this field actually means. Within GDB this will be the signal number that the remote target reports as the stop reason for this thread. Field 'thread_is' - the thread id for this thread. It's implementation defined what this field actually means. Within GDB this will be thread thread-id that is assigned to each remote thread. Field 'x_regs' - at index 0 we store the program counter, and at indices 1 to 31 we store x-registers 1 to 31. x-register 0 is not stored, its value is always zero anyway. Note NT_FPREGSET is optional, its data layout is: fpregset32_t /* For targets with 'F' extension. */ { uint32_t f_regs[32]; uint32_t fcsr; } fpregset64_t /* For targets with 'D' extension . */ { uint64_t f_regs[32]; uint32_t fcsr; } Field 'f_regs' - stores f-registers 0 to 31. Field 'fcsr' - stores the fcsr CSR register, and is always 4-bytes. The rules for ordering the notes is the same as for Linux. The NT_PRSTATUS note must come before any other notes about additional register sets. And for multi-threaded targets all registers for a single thread should be grouped together. This is because only NT_PRSTATUS includes a thread-id, all additional register notes after a NT_PRSTATUS are assumed to belong to the same thread until a different NT_PRSTATUS is seen. gdb/ChangeLog: * Makefile.in (ALL_TARGET_OBS): Add riscv-none-tdep.o. (ALLDEPFILES): Add riscv-none-tdep.c. * configure: Regenerate. * configure.ac (CONFIG_OBS): Add elf-none-tdep.o when BFD has ELF support. * configure.tgt (riscv*-*-*): Include riscv-none-tdep.c. * elf-none-tdep.c: New file. * elf-none-tdep.h: New file. * riscv-none-tdep.c: New file.
2020-11-30 20:15:08 +08:00
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/>. */
/* This file contain code that is specific for bare-metal RISC-V targets. */
#include "defs.h"
#include "arch-utils.h"
#include "regcache.h"
#include "riscv-tdep.h"
#include "elf-bfd.h"
#include "regset.h"
#include "user-regs.h"
#include "target-descriptions.h"
gdb/riscv: introduce bare metal core dump support This commit adds the ability for bare metal RISC-V target to generate core files from within GDB. The intended use case is that a user will connect to a remote bare metal target, debug up to some error condition, then generate a core file in the normal way using: (gdb) generate-core-file This core file can then be used to revisit the state of the remote target without having to reconnect to the remote target. The core file creation code is split between two new files. In elf-none-tdep.c is code for any architecture with the none ABI (i.e. bare metal) when the BFD library is built with ELF support. In riscv-none-tdep.c are the RISC-V specific parts. This is where the regset and regcache_map_entry structures are defined that control how registers are laid out in the core file. As this file could (in theory at least) be used for a non-ELF bare metal RISC-V target, the calls into elf-none-tdep.c are guarded with '#ifdef HAVE_ELF'. Currently for RISC-V only the x-regs and f-regs (if present) are written out. In future commits I plan to add support for writing out the RISC-V CSRs. The core dump format is based around generating an ELF containing sections for the writable regions of memory that a user could be using. Which regions are dumped rely on GDB's existing common core dumping code, GDB will attempt to figure out the stack and heap as well as copying out writable data sections as identified by the original ELF. Register information is added to the core dump using notes, just as it is for Linux of FreeBSD core dumps. The note types used consist of the 3 basic types you would expect in a OS based core dump, NT_PRPSINFO, NT_PRSTATUS, NT_FPREGSET. The layout of these notes differs slightly (due to field sizes) between RV32 and RV64. Below I describe the data layout for each note. In all cases, all padding fields should be set to zero. Note NT_PRPSINFO is optional. Its data layout is: struct prpsinfo32_t /* For RV32. */ { uint8_t padding[32]; char fname[16]; char psargs[80]; } struct prpsinfo64_t /* For RV64. */ { uint8_t padding[40]; char fname[16]; char psargs[80]; } Field 'fname' - null terminated string consisting of the basename of (up to the fist 15 characters of) the executable. Any additional space should be set to zero. If there's no executable name then this field can be set to all zero. Field 'psargs' - a null terminated string up to 80 characters in length. Any additional space should be filled with zero. This field contains the full executable path and any arguments passed to the executable. If there's nothing sensible to write in this field then fill it with zero. Note NT_PRSTATUS is required, its data layout is: struct prstatus32_t /* For RV32. */ { uint8_t padding_1[12]; uint16_t sig; uint8_t padding_2[10]; uint32_t thread_id; uint8_t padding_3[44]; uint32_t x_regs[32]; uint8_t padding_4[4]; } struct prstatus64_t /* For RV64. */ { uint8_t padding_1[12]; uint16_t sig; uint8_t padding_2[18]; uint32_t thread_id; uint8_t padding_3[76]; uint64_t x_regs[32]; uint8_t padding_4[4]; } Field 'sig' - the signal that stopped this thread. It's implementation defined what this field actually means. Within GDB this will be the signal number that the remote target reports as the stop reason for this thread. Field 'thread_is' - the thread id for this thread. It's implementation defined what this field actually means. Within GDB this will be thread thread-id that is assigned to each remote thread. Field 'x_regs' - at index 0 we store the program counter, and at indices 1 to 31 we store x-registers 1 to 31. x-register 0 is not stored, its value is always zero anyway. Note NT_FPREGSET is optional, its data layout is: fpregset32_t /* For targets with 'F' extension. */ { uint32_t f_regs[32]; uint32_t fcsr; } fpregset64_t /* For targets with 'D' extension . */ { uint64_t f_regs[32]; uint32_t fcsr; } Field 'f_regs' - stores f-registers 0 to 31. Field 'fcsr' - stores the fcsr CSR register, and is always 4-bytes. The rules for ordering the notes is the same as for Linux. The NT_PRSTATUS note must come before any other notes about additional register sets. And for multi-threaded targets all registers for a single thread should be grouped together. This is because only NT_PRSTATUS includes a thread-id, all additional register notes after a NT_PRSTATUS are assumed to belong to the same thread until a different NT_PRSTATUS is seen. gdb/ChangeLog: * Makefile.in (ALL_TARGET_OBS): Add riscv-none-tdep.o. (ALLDEPFILES): Add riscv-none-tdep.c. * configure: Regenerate. * configure.ac (CONFIG_OBS): Add elf-none-tdep.o when BFD has ELF support. * configure.tgt (riscv*-*-*): Include riscv-none-tdep.c. * elf-none-tdep.c: New file. * elf-none-tdep.h: New file. * riscv-none-tdep.c: New file.
2020-11-30 20:15:08 +08:00
#ifdef HAVE_ELF
#include "elf-none-tdep.h"
#endif
/* Define the general register mapping. This follows the same format as
the RISC-V linux corefile. The linux 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_gregmap[] =
{
{ 1, RISCV_PC_REGNUM, 0 },
{ 31, RISCV_RA_REGNUM, 0 }, /* x1 to x31 */
{ 0 }
};
/* Define the FP register mapping. This follows the same format as the
RISC-V linux corefile. The kernel puts the 32 FP regs first, and then
FCSR. */
static const struct regcache_map_entry riscv_fregmap[] =
{
{ 32, RISCV_FIRST_FP_REGNUM, 0 },
{ 1, RISCV_CSR_FCSR_REGNUM, 4 }, /* Always stored as 4-bytes. */
{ 0 }
};
/* Define the general register regset. */
static const struct regset riscv_gregset =
{
riscv_gregmap, riscv_supply_regset, regcache_collect_regset
};
/* Define the FP register regset. */
static const struct regset riscv_fregset =
{
riscv_fregmap, riscv_supply_regset, regcache_collect_regset
};
/* Define the CSR regset, this is not constant as the regmap field is
updated dynamically based on the current target description. */
static struct regset riscv_csrset =
{
nullptr, regcache_supply_regset, regcache_collect_regset
};
/* Update the regmap field of RISCV_CSRSET based on the CSRs available in
the current target description. */
static void
riscv_update_csrmap (struct gdbarch *gdbarch,
const struct tdesc_feature *feature_csr)
{
int i = 0;
/* Release any previously defined map. */
delete[] ((struct regcache_map_entry *) riscv_csrset.regmap);
/* Now create a register map for every csr found in the target
description. */
struct regcache_map_entry *riscv_csrmap
= new struct regcache_map_entry[feature_csr->registers.size() + 1];
for (auto &csr : feature_csr->registers)
{
int regnum = user_reg_map_name_to_regnum (gdbarch, csr->name.c_str(),
csr->name.length());
riscv_csrmap[i++] = {1, regnum, 0};
}
/* Mark the end of the array. */
riscv_csrmap[i] = {0};
riscv_csrset.regmap = riscv_csrmap;
}
gdb/riscv: introduce bare metal core dump support This commit adds the ability for bare metal RISC-V target to generate core files from within GDB. The intended use case is that a user will connect to a remote bare metal target, debug up to some error condition, then generate a core file in the normal way using: (gdb) generate-core-file This core file can then be used to revisit the state of the remote target without having to reconnect to the remote target. The core file creation code is split between two new files. In elf-none-tdep.c is code for any architecture with the none ABI (i.e. bare metal) when the BFD library is built with ELF support. In riscv-none-tdep.c are the RISC-V specific parts. This is where the regset and regcache_map_entry structures are defined that control how registers are laid out in the core file. As this file could (in theory at least) be used for a non-ELF bare metal RISC-V target, the calls into elf-none-tdep.c are guarded with '#ifdef HAVE_ELF'. Currently for RISC-V only the x-regs and f-regs (if present) are written out. In future commits I plan to add support for writing out the RISC-V CSRs. The core dump format is based around generating an ELF containing sections for the writable regions of memory that a user could be using. Which regions are dumped rely on GDB's existing common core dumping code, GDB will attempt to figure out the stack and heap as well as copying out writable data sections as identified by the original ELF. Register information is added to the core dump using notes, just as it is for Linux of FreeBSD core dumps. The note types used consist of the 3 basic types you would expect in a OS based core dump, NT_PRPSINFO, NT_PRSTATUS, NT_FPREGSET. The layout of these notes differs slightly (due to field sizes) between RV32 and RV64. Below I describe the data layout for each note. In all cases, all padding fields should be set to zero. Note NT_PRPSINFO is optional. Its data layout is: struct prpsinfo32_t /* For RV32. */ { uint8_t padding[32]; char fname[16]; char psargs[80]; } struct prpsinfo64_t /* For RV64. */ { uint8_t padding[40]; char fname[16]; char psargs[80]; } Field 'fname' - null terminated string consisting of the basename of (up to the fist 15 characters of) the executable. Any additional space should be set to zero. If there's no executable name then this field can be set to all zero. Field 'psargs' - a null terminated string up to 80 characters in length. Any additional space should be filled with zero. This field contains the full executable path and any arguments passed to the executable. If there's nothing sensible to write in this field then fill it with zero. Note NT_PRSTATUS is required, its data layout is: struct prstatus32_t /* For RV32. */ { uint8_t padding_1[12]; uint16_t sig; uint8_t padding_2[10]; uint32_t thread_id; uint8_t padding_3[44]; uint32_t x_regs[32]; uint8_t padding_4[4]; } struct prstatus64_t /* For RV64. */ { uint8_t padding_1[12]; uint16_t sig; uint8_t padding_2[18]; uint32_t thread_id; uint8_t padding_3[76]; uint64_t x_regs[32]; uint8_t padding_4[4]; } Field 'sig' - the signal that stopped this thread. It's implementation defined what this field actually means. Within GDB this will be the signal number that the remote target reports as the stop reason for this thread. Field 'thread_is' - the thread id for this thread. It's implementation defined what this field actually means. Within GDB this will be thread thread-id that is assigned to each remote thread. Field 'x_regs' - at index 0 we store the program counter, and at indices 1 to 31 we store x-registers 1 to 31. x-register 0 is not stored, its value is always zero anyway. Note NT_FPREGSET is optional, its data layout is: fpregset32_t /* For targets with 'F' extension. */ { uint32_t f_regs[32]; uint32_t fcsr; } fpregset64_t /* For targets with 'D' extension . */ { uint64_t f_regs[32]; uint32_t fcsr; } Field 'f_regs' - stores f-registers 0 to 31. Field 'fcsr' - stores the fcsr CSR register, and is always 4-bytes. The rules for ordering the notes is the same as for Linux. The NT_PRSTATUS note must come before any other notes about additional register sets. And for multi-threaded targets all registers for a single thread should be grouped together. This is because only NT_PRSTATUS includes a thread-id, all additional register notes after a NT_PRSTATUS are assumed to belong to the same thread until a different NT_PRSTATUS is seen. gdb/ChangeLog: * Makefile.in (ALL_TARGET_OBS): Add riscv-none-tdep.o. (ALLDEPFILES): Add riscv-none-tdep.c. * configure: Regenerate. * configure.ac (CONFIG_OBS): Add elf-none-tdep.o when BFD has ELF support. * configure.tgt (riscv*-*-*): Include riscv-none-tdep.c. * elf-none-tdep.c: New file. * elf-none-tdep.h: New file. * riscv-none-tdep.c: New file.
2020-11-30 20:15:08 +08:00
/* Implement the "iterate_over_regset_sections" gdbarch method. */
static void
riscv_iterate_over_regset_sections (struct gdbarch *gdbarch,
iterate_over_regset_sections_cb *cb,
void *cb_data,
const struct regcache *regcache)
{
/* Write out the GPRs. */
int sz = 32 * riscv_isa_xlen (gdbarch);
cb (".reg", sz, sz, &riscv_gregset, NULL, cb_data);
/* Write out the FPRs, but only if present. */
if (riscv_isa_flen (gdbarch) > 0)
{
sz = (32 * riscv_isa_flen (gdbarch)
+ register_size (gdbarch, RISCV_CSR_FCSR_REGNUM));
cb (".reg2", sz, sz, &riscv_fregset, NULL, cb_data);
}
/* Read or write the CSRs. The set of CSRs is defined by the current
target description. The user is responsible for ensuring that the
same target description is in use when reading the core file as was
in use when writing the core file. */
const struct target_desc *tdesc = gdbarch_target_desc (gdbarch);
/* Do not dump/load any CSRs if there is no target description or the target
description does not contain any CSRs. */
if (tdesc != nullptr)
{
const struct tdesc_feature *feature_csr
= tdesc_find_feature (tdesc, riscv_feature_name_csr);
if (feature_csr != nullptr && feature_csr->registers.size () > 0)
{
riscv_update_csrmap (gdbarch, feature_csr);
cb (".reg-riscv-csr",
(feature_csr->registers.size() * riscv_isa_xlen (gdbarch)),
(feature_csr->registers.size() * riscv_isa_xlen (gdbarch)),
&riscv_csrset, NULL, cb_data);
}
}
gdb/riscv: introduce bare metal core dump support This commit adds the ability for bare metal RISC-V target to generate core files from within GDB. The intended use case is that a user will connect to a remote bare metal target, debug up to some error condition, then generate a core file in the normal way using: (gdb) generate-core-file This core file can then be used to revisit the state of the remote target without having to reconnect to the remote target. The core file creation code is split between two new files. In elf-none-tdep.c is code for any architecture with the none ABI (i.e. bare metal) when the BFD library is built with ELF support. In riscv-none-tdep.c are the RISC-V specific parts. This is where the regset and regcache_map_entry structures are defined that control how registers are laid out in the core file. As this file could (in theory at least) be used for a non-ELF bare metal RISC-V target, the calls into elf-none-tdep.c are guarded with '#ifdef HAVE_ELF'. Currently for RISC-V only the x-regs and f-regs (if present) are written out. In future commits I plan to add support for writing out the RISC-V CSRs. The core dump format is based around generating an ELF containing sections for the writable regions of memory that a user could be using. Which regions are dumped rely on GDB's existing common core dumping code, GDB will attempt to figure out the stack and heap as well as copying out writable data sections as identified by the original ELF. Register information is added to the core dump using notes, just as it is for Linux of FreeBSD core dumps. The note types used consist of the 3 basic types you would expect in a OS based core dump, NT_PRPSINFO, NT_PRSTATUS, NT_FPREGSET. The layout of these notes differs slightly (due to field sizes) between RV32 and RV64. Below I describe the data layout for each note. In all cases, all padding fields should be set to zero. Note NT_PRPSINFO is optional. Its data layout is: struct prpsinfo32_t /* For RV32. */ { uint8_t padding[32]; char fname[16]; char psargs[80]; } struct prpsinfo64_t /* For RV64. */ { uint8_t padding[40]; char fname[16]; char psargs[80]; } Field 'fname' - null terminated string consisting of the basename of (up to the fist 15 characters of) the executable. Any additional space should be set to zero. If there's no executable name then this field can be set to all zero. Field 'psargs' - a null terminated string up to 80 characters in length. Any additional space should be filled with zero. This field contains the full executable path and any arguments passed to the executable. If there's nothing sensible to write in this field then fill it with zero. Note NT_PRSTATUS is required, its data layout is: struct prstatus32_t /* For RV32. */ { uint8_t padding_1[12]; uint16_t sig; uint8_t padding_2[10]; uint32_t thread_id; uint8_t padding_3[44]; uint32_t x_regs[32]; uint8_t padding_4[4]; } struct prstatus64_t /* For RV64. */ { uint8_t padding_1[12]; uint16_t sig; uint8_t padding_2[18]; uint32_t thread_id; uint8_t padding_3[76]; uint64_t x_regs[32]; uint8_t padding_4[4]; } Field 'sig' - the signal that stopped this thread. It's implementation defined what this field actually means. Within GDB this will be the signal number that the remote target reports as the stop reason for this thread. Field 'thread_is' - the thread id for this thread. It's implementation defined what this field actually means. Within GDB this will be thread thread-id that is assigned to each remote thread. Field 'x_regs' - at index 0 we store the program counter, and at indices 1 to 31 we store x-registers 1 to 31. x-register 0 is not stored, its value is always zero anyway. Note NT_FPREGSET is optional, its data layout is: fpregset32_t /* For targets with 'F' extension. */ { uint32_t f_regs[32]; uint32_t fcsr; } fpregset64_t /* For targets with 'D' extension . */ { uint64_t f_regs[32]; uint32_t fcsr; } Field 'f_regs' - stores f-registers 0 to 31. Field 'fcsr' - stores the fcsr CSR register, and is always 4-bytes. The rules for ordering the notes is the same as for Linux. The NT_PRSTATUS note must come before any other notes about additional register sets. And for multi-threaded targets all registers for a single thread should be grouped together. This is because only NT_PRSTATUS includes a thread-id, all additional register notes after a NT_PRSTATUS are assumed to belong to the same thread until a different NT_PRSTATUS is seen. gdb/ChangeLog: * Makefile.in (ALL_TARGET_OBS): Add riscv-none-tdep.o. (ALLDEPFILES): Add riscv-none-tdep.c. * configure: Regenerate. * configure.ac (CONFIG_OBS): Add elf-none-tdep.o when BFD has ELF support. * configure.tgt (riscv*-*-*): Include riscv-none-tdep.c. * elf-none-tdep.c: New file. * elf-none-tdep.h: New file. * riscv-none-tdep.c: New file.
2020-11-30 20:15:08 +08:00
}
/* Initialize RISC-V bare-metal ABI info. */
static void
riscv_none_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
#ifdef HAVE_ELF
elf_none_init_abi (gdbarch);
#endif
/* Iterate over registers for reading and writing bare metal RISC-V core
files. */
set_gdbarch_iterate_over_regset_sections
(gdbarch, riscv_iterate_over_regset_sections);
}
/* Initialize RISC-V bare-metal target support. */
void _initialize_riscv_none_tdep ();
void
_initialize_riscv_none_tdep ()
{
gdbarch_register_osabi (bfd_arch_riscv, 0, GDB_OSABI_NONE,
riscv_none_init_abi);
}