x86: Avoid pr_cont() in show_opcodes()
If concurrent printk() messages are emitted, then pr_cont() is making it extremly hard to decode which part of the output belongs to what. See the convoluted example at: https://syzkaller.appspot.com/text?tag=CrashReport&x=139d342c400000 Avoid this by using a proper prefix for each line and by using %ph format in show_opcodes() which emits the 'Code:' line in one go. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: joe@perches.com Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@suse.de> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lkml.kernel.org/r/1532009278-5953-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
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@ -22,8 +22,6 @@
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#include <asm/stacktrace.h>
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#include <asm/unwind.h>
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#define OPCODE_BUFSIZE 64
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int panic_on_unrecovered_nmi;
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int panic_on_io_nmi;
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static int die_counter;
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@ -93,26 +91,18 @@ static void printk_stack_address(unsigned long address, int reliable,
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*/
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void show_opcodes(u8 *rip, const char *loglvl)
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{
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unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
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#define PROLOGUE_SIZE 42
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#define EPILOGUE_SIZE 21
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#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)
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u8 opcodes[OPCODE_BUFSIZE];
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u8 *ip;
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int i;
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printk("%sCode: ", loglvl);
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ip = (u8 *)rip - code_prologue;
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if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) {
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pr_cont("Bad RIP value.\n");
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return;
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if (probe_kernel_read(opcodes, rip - PROLOGUE_SIZE, OPCODE_BUFSIZE)) {
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printk("%sCode: Bad RIP value.\n", loglvl);
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} else {
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printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"
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__stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes,
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opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1);
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}
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for (i = 0; i < OPCODE_BUFSIZE; i++, ip++) {
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if (ip == rip)
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pr_cont("<%02x> ", opcodes[i]);
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else
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pr_cont("%02x ", opcodes[i]);
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}
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pr_cont("\n");
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}
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void show_ip(struct pt_regs *regs, const char *loglvl)
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