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Subject[RFC PATCH -tip 14/16] x86: Indicate trapped address and probed address
From
Date
Show trapped address as a comment style on disassembled
code when kernel panicks.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu@gmail.com>
---
arch/x86/kernel/dumpstack.c | 62 +++++++++++++++++++++++++++++++++----------
1 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 2966142..098e61a 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -322,22 +322,63 @@ static unsigned long find_instruction_boundary(unsigned long saddr,
return addr;
}

+static int disasm_printk(unsigned long addr, unsigned long *next,
+ unsigned long ip)
+{
+ char buf[DISASM_STR_LEN];
+ u8 kbuf[MAX_INSN_SIZE];
+ struct insn insn;
+ unsigned long fixed;
+ int i, ret;
+ u8 *v = (u8 *)addr;
+
+ /* recover if the instruction is probed */
+ fixed = recover_probed_instruction(kbuf, addr);
+ kernel_insn_init(&insn, (void *)fixed);
+ insn_get_length(&insn);
+ insn.kaddr = (void *)addr;
+
+ printk(KERN_CONT "%p: ", v);
+ for (i = 0; i < MAX_INSN_SIZE / 2 && i < insn.length; i++)
+ printk(KERN_CONT "%02x ", ((u8 *)v)[i]);
+ if (i != MAX_INSN_SIZE / 2)
+ printk(KERN_CONT "%*s", 3 * (MAX_INSN_SIZE / 2 - i), " ");
+
+ /* print assembly code */
+ ret = disassemble(buf, DISASM_STR_LEN, &insn);
+ if (ret < 0)
+ return ret;
+ printk(KERN_CONT "%s%s%s\n", (fixed != addr) ? "(probed)" : "", buf,
+ (addr == ip) ? "\t<-- trapping instruction" : "");
+
+ if (i < insn.length) {
+ printk(KERN_CONT "%p: ", v + i);
+ for (; i < insn.length - 1; i++)
+ printk(KERN_CONT "%02x ", ((u8 *)v)[i]);
+ printk(KERN_CONT "%02x\n", ((u8 *)v)[i]);
+ }
+
+ if (next)
+ *next = addr + insn.length;
+
+ return 0;
+}
+
/* Disassemble between (ip - prologue) to (ip - prologue + length) */
static int disassemble_code_dump(unsigned long ip, unsigned long prologue,
unsigned long length)
{
- kprobe_opcode_t buf[MAX_INSN_SIZE];
- unsigned long offs, addr, fixed;
- unsigned long saddr = ip - prologue;
+ unsigned long offs;
+ unsigned long addr = ip - prologue;
unsigned long eaddr = ip - prologue + length;
char buf[KSYM_NAME_LEN] = {0};
char *modname;

/* given address must be in text area */
- if (!kernel_text_address(saddr) || !kernel_text_address(eaddr))
+ if (!kernel_text_address(addr) || !kernel_text_address(eaddr))
return -EINVAL;

- addr = find_instruction_boundary(saddr, &offs, &modname, buf);
+ addr = find_instruction_boundary(addr, &offs, &modname, buf);
if (!addr)
return -EINVAL;

@@ -348,15 +389,8 @@ static int disassemble_code_dump(unsigned long ip, unsigned long prologue,
printk(KERN_CONT "\n<%s+0x%lx>:\n", buf, addr - (ip - offs));

do {
- if (addr == ip)
- printk(KERN_CONT ">>");
- fixed = recover_probed_instruction(buf, addr);
- kernel_insn_init(&insn, (void *)fixed);
- insn_get_length(&insn);
- insn.kaddr = addr;
- snprint_assembly(buf, sizeof(buf), &insn, DISASM_PR_ALL);
- printk(KERN_CONT "%s", buf);
- addr += insn.length;
+ if (disasm_printk(addr, &addr, ip) < 0)
+ break;
} while (addr < eaddr);

return 0;


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