From ee72e0e70cf7c846a4e0b6160f771da8f68571dc Mon Sep 17 00:00:00 2001
From: Vincent Chen <vincentc@andestech.com>
Date: Tue, 5 Mar 2019 11:23:34 +0800
Subject: [PATCH] riscv: Add the support for c.ebreak check in
is_valid_bugaddr()
The macro __BUG_INSN currently is defined as the "ebreak" opcode.
The is_valid_bugaddr() function compares the instruction pointed to by
$sepc with macro __BUG_INSN to check whether the current trap exception
is caused by an "ebreak" instruction. However, this check flow is possibly
erroneous because if C extension is supported, the expected trap
instruction "ebreak" is possibly translated to "c.ebreak" by the assembler.
Therefore, it requires a mechanism to distinguish the length of the
instruction in $spec and compare it to the correct trap instruction.
Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
---
arch/riscv/include/asm/bug.h | 7 ++++++-
arch/riscv/kernel/traps.c | 20 +++++++++++++++++---
2 files changed, 23 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/include/asm/bug.h b/arch/riscv/include/asm/bug.h
index 4d906d82277b1..52a1fbdeab3bb 100644
--- a/arch/riscv/include/asm/bug.h
+++ b/arch/riscv/include/asm/bug.h
@@ -21,7 +21,12 @@
#include <asm/asm.h>
#ifdef CONFIG_GENERIC_BUG
-#define __BUG_INSN _AC(0x00100073, UL) /* ebreak */
+#define __INSN_LENGTH_MASK _UL(0x3)
+#define __INSN_LENGTH_32 _UL(0x3)
+#define __COMPRESSED_INSN_MASK _UL(0xffff)
+
+#define __BUG_INSN_32 _UL(0x00100073) /* ebreak */
+#define __BUG_INSN_16 _UL(0x9002) /* c.ebreak */
#ifndef __ASSEMBLY__
typedef u32 bug_insn_t;
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index cc9405420c709..c34cc5418e21b 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -118,6 +118,17 @@ DO_ERROR_INFO(do_trap_ecall_s,
DO_ERROR_INFO(do_trap_ecall_m,
SIGILL, ILL_ILLTRP, "environment call from M-mode");
+#ifdef CONFIG_GENERIC_BUG
+static inline unsigned long get_break_insn_length(unsigned long pc)
+{
+ bug_insn_t insn;
+
+ if (probe_kernel_address((bug_insn_t *)pc, insn))
+ return 0;
+ return (((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ? 4UL : 2UL);
+}
+#endif /* CONFIG_GENERIC_BUG */
+
asmlinkage void do_trap_break(struct pt_regs *regs)
{
#ifdef CONFIG_GENERIC_BUG
@@ -129,8 +140,8 @@ asmlinkage void do_trap_break(struct pt_regs *regs)
case BUG_TRAP_TYPE_NONE:
break;
case BUG_TRAP_TYPE_WARN:
- regs->sepc += sizeof(bug_insn_t);
- return;
+ regs->sepc += get_break_insn_length(regs->sepc);
+ break;
case BUG_TRAP_TYPE_BUG:
die(regs, "Kernel BUG");
}
@@ -149,7 +160,10 @@ int is_valid_bugaddr(unsigned long pc)
return 0;
if (probe_kernel_address((bug_insn_t *)pc, insn))
return 0;
- return (insn == __BUG_INSN);
+ if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
+ return (insn == __BUG_INSN_32);
+ else
+ return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16);
}
#endif /* CONFIG_GENERIC_BUG */
--
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