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Rozycki" To: "gdb-patches@sourceware.org" CC: Jim Wilson , Andrew Burgess , Palmer Dabbelt , Tom Tromey , "guoren@kernel.org" , "lifang_xia@c-sky.com" , "yunhai_shang@c-sky.com" , "jiangshuai_li@c-sky.com" Subject: [PATCH v4 3/3] gdbserver: Add RISC-V/Linux support Date: Sat, 1 Feb 2020 00:07:13 +0000 Message-ID: References: In-Reply-To: authentication-results: spf=none (sender IP is ) smtp.mailfrom=macro@wdc.com; x-ms-exchange-transport-forked: True wdcipoutbound: EOP-TRUE x-ms-oob-tlc-oobclassifiers: OLM:9508; x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-messagedata: 9ibSQqVcaxl12Fo77KsSkVImmR5Xil9A9Gcs/8cp8ruPtcKixuxvFByLrXLqno6PkPhmuSoHN9k5I8JlisY5/NOAjF7Fhw/EM8fNTfRsmPjBcsdS66ROjB5B1tzoQnR47b58N5fpDpmojAVRXV2Kbg== Content-ID: MIME-Version: 1.0 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: z2su1saMTOEacTckkQgBZ2tZBxLo54M0o+YSrtehUKH5B2/cfE2tAUqUWwOv7kBf Implement RISC-V/Linux support for both RV64 and RV32 systems, including XML target description handling based on features determined, GPR and FPR regset support including dynamic sizing of the latter, and software breakpoint handling. Define two NT_FPREGSET regsets of a different size matching the FPR sizes supported for generic `gdbserver' code to pick from according to what the OS supplies. Also handle a glibc bug where ELF_NFPREG is defined in terms of NFPREG, however NFPREG is nowhere defined. gdb/ * arch/riscv.h (riscv_create_target_description): Remove `const' qualifier from the return type. * arch/riscv.c (riscv_create_target_description): Likewise. * nat/riscv-linux-tdesc.h (riscv_linux_read_description): Likewise. * nat/riscv-linux-tdesc.c (riscv_linux_read_description): Likewise. * configure.tgt : Set build_gdbserver=yes. gdb/gdbserver/ * linux-riscv-low.c: New file. * Makefile.in (SFILES): Add linux-riscv-low.c, arch/riscv.c, and nat/riscv-linux-tdesc.c. * configure.srv (srv_tgtobj) (srv_linux_regsets, srv_linux_usrregs, srv_linux_thread_db): Define. --- Changes from v3: - Actually include changes from v2. Changes from v2: - Advance through the buffer accessed in `riscv_fill_fpregset' and `riscv_store_fpregset' so as to avoid doing a variable multiplication in a loop; rename the `regset' variable to `regbuf'. - Use OPTIONAL_REGS rather than FP_REGS as the type for the floating-point regsets. - Add comments throughout. Changes from v1: - Make `gdbserver' selected for automatic build in a RISC-V/Linux/native GDB configuration (thanks, Jim, for pointing this out!). - Remove most of `riscv_arch_setup' and use `riscv_linux_read_description' from 2/3 instead. - Stop using `elf_fpregset_t*' in favour to just a raw `gdb_byte *' buffer and size the regset according to the FPR size in `riscv_fill_fpregset' and `riscv_store_fpregset'. - Define 2 NT_FPREGSET regsets of a different size for generic `gdbserver' code to pick from according to what the OS supplies. --- gdb/arch/riscv.c | 2 gdb/arch/riscv.h | 4 gdb/configure.tgt | 1 gdb/gdbserver/Makefile.in | 3 gdb/gdbserver/configure.srv | 7 + gdb/gdbserver/linux-riscv-low.c | 274 ++++++++++++++++++++++++++++++++++++++++ gdb/nat/riscv-linux-tdesc.c | 2 gdb/nat/riscv-linux-tdesc.h | 2 8 files changed, 290 insertions(+), 5 deletions(-) gdb-riscv-gdbserver-linux.diff Index: binutils-gdb/gdb/arch/riscv.c =================================================================== --- binutils-gdb.orig/gdb/arch/riscv.c +++ binutils-gdb/gdb/arch/riscv.c @@ -43,7 +43,7 @@ static std::unordered_map. */ + +#include "server.h" + +#include "linux-low.h" +#include "tdesc.h" +#include "elf/common.h" +#include "nat/riscv-linux-tdesc.h" +#include "opcode/riscv.h" + +/* Work around glibc header breakage causing ELF_NFPREG not to be usable. */ +#ifndef NFPREG +# define NFPREG 33 +#endif + +/* Implementation of linux_target_ops method "arch_setup". */ + +static void +riscv_arch_setup () +{ + static const char *expedite_regs[] = { "sp", "pc", NULL }; + target_desc *tdesc; + + tdesc = riscv_linux_read_description (lwpid_of (current_thread)); + if (!tdesc->expedite_regs) + init_target_desc (tdesc, expedite_regs); + current_process ()->tdesc = tdesc; +} + +/* Collect GPRs from REGCACHE into BUF. */ + +static void +riscv_fill_gregset (struct regcache *regcache, void *buf) +{ + const struct target_desc *tdesc = regcache->tdesc; + elf_gregset_t *regset = (elf_gregset_t *) buf; + int regno = find_regno (tdesc, "zero"); + int i; + + collect_register_by_name (regcache, "pc", *regset); + for (i = 1; i < ARRAY_SIZE (*regset); i++) + collect_register (regcache, regno + i, *regset + i); +} + +/* Supply GPRs from BUF into REGCACHE. */ + +static void +riscv_store_gregset (struct regcache *regcache, const void *buf) +{ + const elf_gregset_t *regset = (const elf_gregset_t *) buf; + const struct target_desc *tdesc = regcache->tdesc; + int regno = find_regno (tdesc, "zero"); + int i; + + supply_register_by_name (regcache, "pc", *regset); + supply_register_zeroed (regcache, regno); + for (i = 1; i < ARRAY_SIZE (*regset); i++) + supply_register (regcache, regno + i, *regset + i); +} + +/* Collect FPRs from REGCACHE into BUF. */ + +static void +riscv_fill_fpregset (struct regcache *regcache, void *buf) +{ + const struct target_desc *tdesc = regcache->tdesc; + int regno = find_regno (tdesc, "ft0"); + int flen = register_size (regcache->tdesc, regno); + gdb_byte *regbuf = (gdb_byte *) buf; + int i; + + for (i = 0; i < ELF_NFPREG - 1; i++, regbuf += flen) + collect_register (regcache, regno + i, regbuf); + collect_register_by_name (regcache, "fcsr", regbuf); +} + +/* Supply FPRs from BUF into REGCACHE. */ + +static void +riscv_store_fpregset (struct regcache *regcache, const void *buf) +{ + const struct target_desc *tdesc = regcache->tdesc; + int regno = find_regno (tdesc, "ft0"); + int flen = register_size (regcache->tdesc, regno); + const gdb_byte *regbuf = (const gdb_byte *) buf; + int i; + + for (i = 0; i < ELF_NFPREG - 1; i++, regbuf += flen) + supply_register (regcache, regno + i, regbuf); + supply_register_by_name (regcache, "fcsr", regbuf); +} + +/* RISC-V/Linux regsets. FPRs are optional and come in different sizes, + so define multiple regsets for them marking them all as OPTIONAL_REGS + rather than FP_REGS, so that "regsets_fetch_inferior_registers" picks + the right one according to size. */ +static struct regset_info riscv_regsets[] = { + { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_PRSTATUS, + sizeof (elf_gregset_t), GENERAL_REGS, + riscv_fill_gregset, riscv_store_gregset }, + { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_FPREGSET, + sizeof (struct __riscv_mc_d_ext_state), OPTIONAL_REGS, + riscv_fill_fpregset, riscv_store_fpregset }, + { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_FPREGSET, + sizeof (struct __riscv_mc_f_ext_state), OPTIONAL_REGS, + riscv_fill_fpregset, riscv_store_fpregset }, + NULL_REGSET +}; + +/* RISC-V/Linux regset information. */ +static struct regsets_info riscv_regsets_info = + { + riscv_regsets, /* regsets */ + 0, /* num_regsets */ + NULL, /* disabled_regsets */ + }; + +/* Definition of linux_target_ops data member "regs_info". */ +static struct regs_info riscv_regs = + { + NULL, /* regset_bitmap */ + NULL, /* usrregs */ + &riscv_regsets_info, + }; + +/* Implementation of linux_target_ops method "regs_info". */ + +static const struct regs_info * +riscv_regs_info () +{ + return &riscv_regs; +} + +/* Implementation of linux_target_ops method "fetch_register". */ + +static int +riscv_fetch_register (struct regcache *regcache, int regno) +{ + const struct target_desc *tdesc = regcache->tdesc; + + if (regno != find_regno (tdesc, "zero")) + return 0; + supply_register_zeroed (regcache, regno); + return 1; +} + +/* Implementation of linux_target_ops method "get_pc". */ + +static CORE_ADDR +riscv_get_pc (struct regcache *regcache) +{ + elf_gregset_t regset; + + if (sizeof (regset[0]) == 8) + return linux_get_pc_64bit (regcache); + else + return linux_get_pc_32bit (regcache); +} + +/* Implementation of linux_target_ops method "set_pc". */ + +static void +riscv_set_pc (struct regcache *regcache, CORE_ADDR newpc) +{ + elf_gregset_t regset; + + if (sizeof (regset[0]) == 8) + linux_set_pc_64bit (regcache, newpc); + else + linux_set_pc_32bit (regcache, newpc); +} + +/* Correct in either endianness. */ +static const uint16_t riscv_ibreakpoint[] = { 0x0073, 0x0010 }; +static const uint16_t riscv_cbreakpoint = 0x9002; + +/* Implementation of linux_target_ops method "breakpoint_kind_from_pc". */ + +static int +riscv_breakpoint_kind_from_pc (CORE_ADDR *pcptr) +{ + union + { + gdb_byte bytes[2]; + uint16_t insn; + } + buf; + + if (target_read_memory (*pcptr, buf.bytes, sizeof (buf.insn)) == 0 + && riscv_insn_length (buf.insn == sizeof (riscv_ibreakpoint))) + return sizeof (riscv_ibreakpoint); + else + return sizeof (riscv_cbreakpoint); +} + +/* Implementation of linux_target_ops method "sw_breakpoint_from_kind". */ + +static const gdb_byte * +riscv_sw_breakpoint_from_kind (int kind, int *size) +{ + *size = kind; + switch (kind) + { + case sizeof (riscv_ibreakpoint): + return (const gdb_byte *) &riscv_ibreakpoint; + default: + return (const gdb_byte *) &riscv_cbreakpoint; + } +} + +/* Implementation of linux_target_ops method "breakpoint_at". */ + +static int +riscv_breakpoint_at (CORE_ADDR pc) +{ + union + { + gdb_byte bytes[2]; + uint16_t insn; + } + buf; + + if (target_read_memory (pc, buf.bytes, sizeof (buf.insn)) == 0 + && (buf.insn == riscv_cbreakpoint + || (buf.insn == riscv_ibreakpoint[0] + && target_read_memory (pc + sizeof (buf.insn), buf.bytes, + sizeof (buf.insn)) == 0 + && buf.insn == riscv_ibreakpoint[1]))) + return 1; + else + return 0; +} + +/* RISC-V/Linux target operations. */ +struct linux_target_ops the_low_target = +{ + riscv_arch_setup, + riscv_regs_info, + NULL, /* cannot_fetch_register */ + NULL, /* cannot_store_register */ + riscv_fetch_register, + riscv_get_pc, + riscv_set_pc, + riscv_breakpoint_kind_from_pc, + riscv_sw_breakpoint_from_kind, + NULL, /* get_next_pcs */ + 0, /* decr_pc_after_break */ + riscv_breakpoint_at, +}; + +/* Initialize the RISC-V/Linux target. */ + +void +initialize_low_arch () +{ + initialize_regsets_info (&riscv_regsets_info); +} Index: binutils-gdb/gdb/nat/riscv-linux-tdesc.c =================================================================== --- binutils-gdb.orig/gdb/nat/riscv-linux-tdesc.c +++ binutils-gdb/gdb/nat/riscv-linux-tdesc.c @@ -33,7 +33,7 @@ /* Determine XLEN and FLEN and return a corresponding target description. */ -const struct target_desc * +struct target_desc * riscv_linux_read_description (int tid) { struct riscv_gdbarch_features features; Index: binutils-gdb/gdb/nat/riscv-linux-tdesc.h =================================================================== --- binutils-gdb.orig/gdb/nat/riscv-linux-tdesc.h +++ binutils-gdb/gdb/nat/riscv-linux-tdesc.h @@ -22,6 +22,6 @@ struct target_desc; /* Return a target description for the LWP identified by TID. */ -const struct target_desc *riscv_linux_read_description (int tid); +struct target_desc *riscv_linux_read_description (int tid); #endif /* NAT_RISCV_LINUX_TDESC_H */