linux-kernel - [PATCH 9/9] x86/dumpstack: Save first regs set for the executive summary

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Date:   Tue,  6 Mar 2018 10:49:20 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 9/9] x86/dumpstack: Save first regs set for the executive summary

From: Borislav Petkov <bp@...e.de>

Save the regs set when we call __die() for the first time and print it
in oops_end().

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/dumpstack.c | 33 ++++++++++++---------------------
 1 file changed, 12 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index e855815b00d4..409a5bd02a18 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -31,6 +31,8 @@ static u8 __opc[OPCODE_BUFSIZE];
 static u8 *opcodes = __opc;
 static int die_counter;
 
+static struct pt_regs exec_summary_regs;
+
 bool in_task_stack(unsigned long *stack, struct task_struct *task,
 		   struct stack_info *info)
 {
@@ -325,6 +327,9 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
 	raw_local_irq_restore(flags);
 	oops_exit();
 
+	/* Executive summary in case the oops scrolled away */
+	__show_regs(&exec_summary_regs, false);
+
 	if (!signr)
 		return;
 	if (in_interrupt())
@@ -343,10 +348,10 @@ NOKPROBE_SYMBOL(oops_end);
 
 int __die(const char *str, struct pt_regs *regs, long err)
 {
-#ifdef CONFIG_X86_32
-	unsigned short ss;
-	unsigned long sp;
-#endif
+	/* Save the regs of the first oops for the executive summary later. */
+	if (!die_counter)
+		exec_summary_regs = *regs;
+
 	printk(KERN_DEFAULT
 	       "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
 	       IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT"         : "",
@@ -356,26 +361,14 @@ int __die(const char *str, struct pt_regs *regs, long err)
 	       IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
 	       (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
 
+	show_regs(regs);
+
 	if (notify_die(DIE_OOPS, str, regs, err,
 			current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
 		return 1;
 
 	print_modules();
-	show_regs(regs);
-#ifdef CONFIG_X86_32
-	if (user_mode(regs)) {
-		sp = regs->sp;
-		ss = regs->ss;
-	} else {
-		sp = kernel_stack_pointer(regs);
-		savesegment(ss, ss);
-	}
-	printk(KERN_EMERG "EIP: %pS SS:ESP: %04x:%08lx\n",
-	       (void *)regs->ip, ss, sp);
-#else
-	/* Executive summary in case the oops scrolled away */
-	printk(KERN_ALERT "RIP: %pS RSP: %016lx\n", (void *)regs->ip, regs->sp);
-#endif
+
 	return 0;
 }
 NOKPROBE_SYMBOL(__die);
@@ -442,7 +435,5 @@ void show_regs(struct pt_regs *regs)
 
 		if (regs->ip < PAGE_OFFSET)
 			pr_cont(" Bad RIP value.\n");
-		else
-			show_opcodes((u8 *)regs->ip, KERN_DEFAULT);
 	}
 }
-- 
2.13.0