arm64/BUG: Use BRK instruction for generic BUG traps (9fb7410f) · Commits · 戴 / test

arch/arm64/Kconfig

+8 −0

Original line number	Diff line number	Diff line
		@@ -113,6 +113,14 @@ config TRACE_IRQFLAGS_SUPPORT
		config RWSEM_XCHGADD_ALGORITHM
		def_bool y

		config GENERIC_BUG
		def_bool y
		depends on BUG

		config GENERIC_BUG_RELATIVE_POINTERS
		def_bool y
		depends on GENERIC_BUG

		config GENERIC_HWEIGHT
		def_bool y

arch/arm64/include/asm/bug.h

0 → 100644

+64 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2015 ARM Limited
		* Author: Dave Martin <Dave.Martin@arm.com>
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*
		* 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/>.
		*/

		#ifndef _ARCH_ARM64_ASM_BUG_H
		#define _ARCH_ARM64_ASM_BUG_H

		#include <asm/debug-monitors.h>

		#ifdef CONFIG_GENERIC_BUG
		#define HAVE_ARCH_BUG

		#ifdef CONFIG_DEBUG_BUGVERBOSE
		#define _BUGVERBOSE_LOCATION(file, line) __BUGVERBOSE_LOCATION(file, line)
		#define __BUGVERBOSE_LOCATION(file, line) \
		".pushsection .rodata.str,\"aMS\",@progbits,1\n" \
		"2: .string \"" file "\"\n\t" \
		".popsection\n\t" \
		\
		".long 2b - 0b\n\t" \
		".short " #line "\n\t"
		#else
		#define _BUGVERBOSE_LOCATION(file, line)
		#endif

		#define _BUG_FLAGS(flags) __BUG_FLAGS(flags)

		#define __BUG_FLAGS(flags) asm volatile ( \
		".pushsection __bug_table,\"a\"\n\t" \
		".align 2\n\t" \
		"0: .long 1f - 0b\n\t" \
		_BUGVERBOSE_LOCATION(__FILE__, __LINE__) \
		".short " #flags "\n\t" \
		".popsection\n" \
		\
		"1: brk %[imm]" \
		:: [imm] "i" (BUG_BRK_IMM) \
		)

		#define BUG() do { \
		_BUG_FLAGS(0); \
		unreachable(); \
		} while (0)

		#define __WARN_TAINT(taint) _BUG_FLAGS(BUGFLAG_TAINT(taint))

		#endif /* ! CONFIG_GENERIC_BUG */

		#include <asm-generic/bug.h>

		#endif /* ! _ARCH_ARM64_ASM_BUG_H */

arch/arm64/include/asm/debug-monitors.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -52,10 +52,12 @@
		* 0x100: for triggering a fault on purpose (reserved)
		* 0x400: for dynamic BRK instruction
		* 0x401: for compile time BRK instruction
		* 0x800: kernel-mode BUG() and WARN() traps
		*/
		#define FAULT_BRK_IMM 0x100
		#define KGDB_DYN_DBG_BRK_IMM 0x400
		#define KGDB_COMPILED_DBG_BRK_IMM 0x401
		#define BUG_BRK_IMM 0x800

		/*
		* BRK instruction encoding

arch/arm64/kernel/traps.c

+58 −1

Original line number	Diff line number	Diff line
		@@ -17,6 +17,7 @@
		* along with this program. If not, see <http://www.gnu.org/licenses/>.
		*/

		#include <linux/bug.h>
		#include <linux/signal.h>
		#include <linux/personality.h>
		#include <linux/kallsyms.h>
		@@ -32,8 +33,10 @@
		#include <linux/syscalls.h>

		#include <asm/atomic.h>
		#include <asm/bug.h>
		#include <asm/debug-monitors.h>
		#include <asm/esr.h>
		#include <asm/insn.h>
		#include <asm/traps.h>
		#include <asm/stacktrace.h>
		#include <asm/exception.h>
		@@ -466,7 +469,61 @@ void __pgd_error(const char *file, int line, unsigned long val)
		pr_crit("%s:%d: bad pgd %016lx.\n", file, line, val);
		}

		/* GENERIC_BUG traps */

		int is_valid_bugaddr(unsigned long addr)
		{
		/*
		* bug_handler() only called for BRK #BUG_BRK_IMM.
		* So the answer is trivial -- any spurious instances with no
		* bug table entry will be rejected by report_bug() and passed
		* back to the debug-monitors code and handled as a fatal
		* unexpected debug exception.
		*/
		return 1;
		}

		static int bug_handler(struct pt_regs *regs, unsigned int esr)
		{
		if (user_mode(regs))
		return DBG_HOOK_ERROR;

		switch (report_bug(regs->pc, regs)) {
		case BUG_TRAP_TYPE_BUG:
		die("Oops - BUG", regs, 0);
		break;

		case BUG_TRAP_TYPE_WARN:
		break;

		default:
		/* unknown/unrecognised bug trap type */
		return DBG_HOOK_ERROR;
		}

		/* If thread survives, skip over the BUG instruction and continue: */
		regs->pc += AARCH64_INSN_SIZE; /* skip BRK and resume */
		return DBG_HOOK_HANDLED;
		}

		static struct break_hook bug_break_hook = {
		.esr_val = 0xf2000000 \| BUG_BRK_IMM,
		.esr_mask = 0xffffffff,
		.fn = bug_handler,
		};

		/*
		* Initial handler for AArch64 BRK exceptions
		* This handler only used until debug_traps_init().
		*/
		int __init early_brk64(unsigned long addr, unsigned int esr,
		struct pt_regs *regs)
		{
		return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
		}

		/* This registration must happen early, before debug_traps_init(). */
		void __init trap_init(void)
		{
		return;
		register_break_hook(&bug_break_hook);
		}

arch/arm64/mm/fault.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -501,14 +501,22 @@ asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
		arm64_notify_die("Oops - SP/PC alignment exception", regs, &info, esr);
		}

		static struct fault_info debug_fault_info[] = {
		int __init early_brk64(unsigned long addr, unsigned int esr,
		struct pt_regs *regs);

		/*
		* __refdata because early_brk64 is __init, but the reference to it is
		* clobbered at arch_initcall time.
		* See traps.c and debug-monitors.c:debug_traps_init().
		*/
		static struct fault_info __refdata debug_fault_info[] = {
		{ do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" },
		{ do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" },
		{ do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" },
		{ do_bad, SIGBUS, 0, "unknown 3" },
		{ do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" },
		{ do_bad, SIGTRAP, 0, "aarch32 vector catch" },
		{ do_bad, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" },
		{ early_brk64, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" },
		{ do_bad, SIGBUS, 0, "unknown 7" },
		};

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