forked from Minki/linux
0d15ef6778
Current versions of gdb do not interoperate cleanly with kgdb on arm64
systems because gdb and kgdb do not use the same register description.
This patch modifies kgdb to work with recent releases of gdb (>= 7.8.1).
Compatibility with gdb (after the patch is applied) is as follows:
gdb-7.6 and earlier Ok
gdb-7.7 series Works if user provides custom target description
gdb-7.8(.0) Works if user provides custom target description
gdb-7.8.1 and later Ok
When commit 44679a4f14 ("arm64: KGDB: Add step debugging support") was
introduced it was paired with a gdb patch that made an incompatible
change to the gdbserver protocol. This patch was eventually merged into
the gdb sources:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=a4d9ba85ec5597a6a556afe26b712e878374b9dd
The change to the protocol was mostly made to simplify big-endian support
inside the kernel gdb stub. Unfortunately the gdb project released
gdb-7.7.x and gdb-7.8.0 before the protocol incompatibility was identified
and reversed:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=bdc144174bcb11e808b4e73089b850cf9620a7ee
This leaves us in a position where kgdb still uses the no-longer-used
protocol; gdb-7.8.1, which restored the original behaviour, was
released on 2014-10-29.
I don't believe it is possible to detect/correct the protocol
incompatiblity which means the kernel must take a view about which
version of the gdb remote protocol is "correct". This patch takes the
view that the original/current version of the protocol is correct
and that version found in gdb-7.7.x and gdb-7.8.0 is anomalous.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
349 lines
9.0 KiB
C
349 lines
9.0 KiB
C
/*
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* AArch64 KGDB support
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*
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* Based on arch/arm/kernel/kgdb.c
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*
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* Copyright (C) 2013 Cavium Inc.
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* Author: Vijaya Kumar K <vijaya.kumar@caviumnetworks.com>
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*
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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 version 2 as
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* published by the Free Software Foundation.
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*
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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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*
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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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*/
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#include <linux/irq.h>
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#include <linux/kdebug.h>
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#include <linux/kgdb.h>
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#include <asm/traps.h>
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struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
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{ "x0", 8, offsetof(struct pt_regs, regs[0])},
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{ "x1", 8, offsetof(struct pt_regs, regs[1])},
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{ "x2", 8, offsetof(struct pt_regs, regs[2])},
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{ "x3", 8, offsetof(struct pt_regs, regs[3])},
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{ "x4", 8, offsetof(struct pt_regs, regs[4])},
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{ "x5", 8, offsetof(struct pt_regs, regs[5])},
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{ "x6", 8, offsetof(struct pt_regs, regs[6])},
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{ "x7", 8, offsetof(struct pt_regs, regs[7])},
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{ "x8", 8, offsetof(struct pt_regs, regs[8])},
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{ "x9", 8, offsetof(struct pt_regs, regs[9])},
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{ "x10", 8, offsetof(struct pt_regs, regs[10])},
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{ "x11", 8, offsetof(struct pt_regs, regs[11])},
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{ "x12", 8, offsetof(struct pt_regs, regs[12])},
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{ "x13", 8, offsetof(struct pt_regs, regs[13])},
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{ "x14", 8, offsetof(struct pt_regs, regs[14])},
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{ "x15", 8, offsetof(struct pt_regs, regs[15])},
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{ "x16", 8, offsetof(struct pt_regs, regs[16])},
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{ "x17", 8, offsetof(struct pt_regs, regs[17])},
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{ "x18", 8, offsetof(struct pt_regs, regs[18])},
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{ "x19", 8, offsetof(struct pt_regs, regs[19])},
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{ "x20", 8, offsetof(struct pt_regs, regs[20])},
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{ "x21", 8, offsetof(struct pt_regs, regs[21])},
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{ "x22", 8, offsetof(struct pt_regs, regs[22])},
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{ "x23", 8, offsetof(struct pt_regs, regs[23])},
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{ "x24", 8, offsetof(struct pt_regs, regs[24])},
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{ "x25", 8, offsetof(struct pt_regs, regs[25])},
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{ "x26", 8, offsetof(struct pt_regs, regs[26])},
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{ "x27", 8, offsetof(struct pt_regs, regs[27])},
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{ "x28", 8, offsetof(struct pt_regs, regs[28])},
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{ "x29", 8, offsetof(struct pt_regs, regs[29])},
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{ "x30", 8, offsetof(struct pt_regs, regs[30])},
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{ "sp", 8, offsetof(struct pt_regs, sp)},
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{ "pc", 8, offsetof(struct pt_regs, pc)},
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/*
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* struct pt_regs thinks PSTATE is 64-bits wide but gdb remote
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* protocol disagrees. Therefore we must extract only the lower
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* 32-bits. Look for the big comment in asm/kgdb.h for more
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* detail.
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*/
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{ "pstate", 4, offsetof(struct pt_regs, pstate)
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#ifdef CONFIG_CPU_BIG_ENDIAN
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+ 4
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#endif
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},
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{ "v0", 16, -1 },
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{ "v1", 16, -1 },
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{ "v2", 16, -1 },
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{ "v3", 16, -1 },
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{ "v4", 16, -1 },
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{ "v5", 16, -1 },
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{ "v6", 16, -1 },
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{ "v7", 16, -1 },
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{ "v8", 16, -1 },
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{ "v9", 16, -1 },
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{ "v10", 16, -1 },
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{ "v11", 16, -1 },
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{ "v12", 16, -1 },
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{ "v13", 16, -1 },
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{ "v14", 16, -1 },
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{ "v15", 16, -1 },
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{ "v16", 16, -1 },
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{ "v17", 16, -1 },
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{ "v18", 16, -1 },
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{ "v19", 16, -1 },
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{ "v20", 16, -1 },
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{ "v21", 16, -1 },
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{ "v22", 16, -1 },
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{ "v23", 16, -1 },
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{ "v24", 16, -1 },
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{ "v25", 16, -1 },
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{ "v26", 16, -1 },
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{ "v27", 16, -1 },
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{ "v28", 16, -1 },
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{ "v29", 16, -1 },
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{ "v30", 16, -1 },
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{ "v31", 16, -1 },
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{ "fpsr", 4, -1 },
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{ "fpcr", 4, -1 },
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};
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char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
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{
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if (regno >= DBG_MAX_REG_NUM || regno < 0)
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return NULL;
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if (dbg_reg_def[regno].offset != -1)
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memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
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dbg_reg_def[regno].size);
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else
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memset(mem, 0, dbg_reg_def[regno].size);
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return dbg_reg_def[regno].name;
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}
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int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
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{
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if (regno >= DBG_MAX_REG_NUM || regno < 0)
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return -EINVAL;
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if (dbg_reg_def[regno].offset != -1)
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memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
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dbg_reg_def[regno].size);
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return 0;
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}
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void
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sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
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{
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struct pt_regs *thread_regs;
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/* Initialize to zero */
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memset((char *)gdb_regs, 0, NUMREGBYTES);
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thread_regs = task_pt_regs(task);
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memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES);
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/* Special case for PSTATE (check comments in asm/kgdb.h for details) */
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dbg_get_reg(33, gdb_regs + GP_REG_BYTES, thread_regs);
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}
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void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
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{
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regs->pc = pc;
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}
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static int compiled_break;
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static void kgdb_arch_update_addr(struct pt_regs *regs,
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char *remcom_in_buffer)
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{
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unsigned long addr;
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char *ptr;
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ptr = &remcom_in_buffer[1];
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if (kgdb_hex2long(&ptr, &addr))
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kgdb_arch_set_pc(regs, addr);
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else if (compiled_break == 1)
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kgdb_arch_set_pc(regs, regs->pc + 4);
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compiled_break = 0;
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}
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int kgdb_arch_handle_exception(int exception_vector, int signo,
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int err_code, char *remcom_in_buffer,
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char *remcom_out_buffer,
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struct pt_regs *linux_regs)
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{
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int err;
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switch (remcom_in_buffer[0]) {
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case 'D':
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case 'k':
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/*
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* Packet D (Detach), k (kill). No special handling
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* is required here. Handle same as c packet.
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*/
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case 'c':
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/*
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* Packet c (Continue) to continue executing.
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* Set pc to required address.
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* Try to read optional parameter and set pc.
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* If this was a compiled breakpoint, we need to move
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* to the next instruction else we will just breakpoint
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* over and over again.
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*/
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kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
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atomic_set(&kgdb_cpu_doing_single_step, -1);
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kgdb_single_step = 0;
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/*
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* Received continue command, disable single step
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*/
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if (kernel_active_single_step())
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kernel_disable_single_step();
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err = 0;
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break;
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case 's':
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/*
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* Update step address value with address passed
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* with step packet.
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* On debug exception return PC is copied to ELR
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* So just update PC.
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* If no step address is passed, resume from the address
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* pointed by PC. Do not update PC
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*/
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kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
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atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id());
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kgdb_single_step = 1;
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/*
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* Enable single step handling
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*/
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if (!kernel_active_single_step())
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kernel_enable_single_step(linux_regs);
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err = 0;
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break;
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default:
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err = -1;
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}
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return err;
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}
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static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
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{
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kgdb_handle_exception(1, SIGTRAP, 0, regs);
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return 0;
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}
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static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
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{
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compiled_break = 1;
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kgdb_handle_exception(1, SIGTRAP, 0, regs);
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return 0;
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}
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static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
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{
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kgdb_handle_exception(1, SIGTRAP, 0, regs);
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return 0;
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}
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static struct break_hook kgdb_brkpt_hook = {
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.esr_mask = 0xffffffff,
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.esr_val = (u32)ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM),
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.fn = kgdb_brk_fn
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};
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static struct break_hook kgdb_compiled_brkpt_hook = {
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.esr_mask = 0xffffffff,
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.esr_val = (u32)ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM),
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.fn = kgdb_compiled_brk_fn
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};
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static struct step_hook kgdb_step_hook = {
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.fn = kgdb_step_brk_fn
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};
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static void kgdb_call_nmi_hook(void *ignored)
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{
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kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
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}
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void kgdb_roundup_cpus(unsigned long flags)
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{
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local_irq_enable();
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smp_call_function(kgdb_call_nmi_hook, NULL, 0);
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local_irq_disable();
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}
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static int __kgdb_notify(struct die_args *args, unsigned long cmd)
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{
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struct pt_regs *regs = args->regs;
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if (kgdb_handle_exception(1, args->signr, cmd, regs))
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return NOTIFY_DONE;
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return NOTIFY_STOP;
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}
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static int
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kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
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{
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unsigned long flags;
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int ret;
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local_irq_save(flags);
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ret = __kgdb_notify(ptr, cmd);
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local_irq_restore(flags);
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return ret;
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}
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static struct notifier_block kgdb_notifier = {
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.notifier_call = kgdb_notify,
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/*
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* Want to be lowest priority
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*/
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.priority = -INT_MAX,
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};
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/*
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* kgdb_arch_init - Perform any architecture specific initialization.
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* This function will handle the initialization of any architecture
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* specific callbacks.
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*/
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int kgdb_arch_init(void)
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{
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int ret = register_die_notifier(&kgdb_notifier);
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if (ret != 0)
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return ret;
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register_break_hook(&kgdb_brkpt_hook);
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register_break_hook(&kgdb_compiled_brkpt_hook);
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register_step_hook(&kgdb_step_hook);
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return 0;
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}
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/*
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* kgdb_arch_exit - Perform any architecture specific uninitalization.
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* This function will handle the uninitalization of any architecture
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* specific callbacks, for dynamic registration and unregistration.
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*/
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void kgdb_arch_exit(void)
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{
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unregister_break_hook(&kgdb_brkpt_hook);
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unregister_break_hook(&kgdb_compiled_brkpt_hook);
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unregister_step_hook(&kgdb_step_hook);
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unregister_die_notifier(&kgdb_notifier);
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}
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/*
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* ARM instructions are always in LE.
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* Break instruction is encoded in LE format
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*/
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struct kgdb_arch arch_kgdb_ops = {
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.gdb_bpt_instr = {
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KGDB_DYN_BRK_INS_BYTE(0),
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KGDB_DYN_BRK_INS_BYTE(1),
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KGDB_DYN_BRK_INS_BYTE(2),
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KGDB_DYN_BRK_INS_BYTE(3),
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}
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};
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