x86: print which shared library/executable faulted in segfault etc. messages v3

They now look like:

hal-resmgr[13791]: segfault at 3c rip 2b9c8caec182 rsp 7fff1e825d30 error 4 in libacl.so.1.1.0[2b9c8caea000+6000]

This makes it easier to pinpoint bugs to specific libraries.

And printing the offset into a mapping also always allows to find the
correct fault point in a library even with randomized mappings. Previously
there was no way to actually find the correct code address inside
the randomized mapping.

Relies on earlier patch to shorten the printk formats.

They are often now longer than 80 characters, but I think that's worth it.

[includes fix from Eric Dumazet to check d_path error value]

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

8 files changed, 63 insertions, 12 deletions

diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
index 74df558..89a690e 100644
--- a/arch/x86/kernel/signal_32.c
+++ b/arch/x86/kernel/signal_32.c
@@ -198,12 +198,15 @@ asmlinkage int sys_sigreturn(unsigned long __unused)
 	return ax;
 
 badframe:
-	if (show_unhandled_signals && printk_ratelimit())
+	if (show_unhandled_signals && printk_ratelimit()) {
 		printk("%s%s[%d] bad frame in sigreturn frame:%p ip:%lx"
-		       " sp:%lx oeax:%lx\n",
+		       " sp:%lx oeax:%lx",
 		    task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 		    current->comm, task_pid_nr(current), frame, regs->ip,
 		    regs->sp, regs->orig_ax);
+		print_vma_addr(" in ", regs->ip);
+		printk("\n");
+	}
 
 	force_sig(SIGSEGV, current);
 	return 0;
diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
index 4eb751c..7347bb1 100644
--- a/arch/x86/kernel/signal_64.c
+++ b/arch/x86/kernel/signal_64.c
@@ -484,9 +484,12 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 { 
 	struct task_struct *me = current; 
-	if (show_unhandled_signals && printk_ratelimit())
-		printk("%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx\n",
+	if (show_unhandled_signals && printk_ratelimit()) {
+		printk("%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 	       me->comm,me->pid,where,frame,regs->ip,regs->sp,regs->orig_ax);
+		print_vma_addr(" in ", regs->ip);
+		printk("\n");
+	}
 
 	force_sig(SIGSEGV, me); 
 } 
diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index 6f3bb28..270cfd4 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -609,11 +609,14 @@ void __kprobes do_general_protection(struct pt_regs * regs,
 	current->thread.error_code = error_code;
 	current->thread.trap_no = 13;
 	if (show_unhandled_signals && unhandled_signal(current, SIGSEGV) &&
-	    printk_ratelimit())
+	    printk_ratelimit()) {
 		printk(KERN_INFO
-		    "%s[%d] general protection ip:%lx sp:%lx error:%lx\n",
+		    "%s[%d] general protection ip:%lx sp:%lx error:%lx",
 		    current->comm, task_pid_nr(current),
 		    regs->ip, regs->sp, error_code);
+		print_vma_addr(" in ", regs->ip);
+		printk("\n");
+	}
 
 	force_sig(SIGSEGV, current);
 	return;
diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c
index 814801f..911ed28 100644
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -642,11 +642,14 @@ static void __kprobes do_trap(int trapnr, int signr, char *str,
 		tsk->thread.trap_no = trapnr;
 
 		if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
-		    printk_ratelimit())
+		    printk_ratelimit()) {
 			printk(KERN_INFO
-			       "%s[%d] trap %s ip:%lx sp:%lx error:%lx\n",
+			       "%s[%d] trap %s ip:%lx sp:%lx error:%lx",
 			       tsk->comm, tsk->pid, str,
 			       regs->ip, regs->sp, error_code);
+			print_vma_addr(" in ", regs->ip);
+			printk("\n");
+		}
 
 		if (info)
 			force_sig_info(signr, info, tsk);
@@ -741,11 +744,14 @@ asmlinkage void __kprobes do_general_protection(struct pt_regs * regs,
 		tsk->thread.trap_no = 13;
 
 		if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
-		    printk_ratelimit())
+		    printk_ratelimit()) {
 			printk(KERN_INFO
-		       "%s[%d] general protection ip:%lx sp:%lx error:%lx\n",
+		       "%s[%d] general protection ip:%lx sp:%lx error:%lx",
 			       tsk->comm, tsk->pid,
 			       regs->ip, regs->sp, error_code);
+			print_vma_addr(" in ", regs->ip);
+			printk("\n");
+		}
 
 		force_sig(SIGSEGV, tsk);
 		return;
diff --git a/arch/x86/mm/fault_32.c b/arch/x86/mm/fault_32.c
index 13d2955..276863d 100644
--- a/arch/x86/mm/fault_32.c
+++ b/arch/x86/mm/fault_32.c
@@ -514,11 +514,13 @@ bad_area_nosemaphore:
 #ifdef CONFIG_X86_32
 			"%s%s[%d]: segfault at %lx ip %08lx sp %08lx error %lx",
 #else
-			"%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx\n",
+			"%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx",
 #endif
 			task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 			tsk->comm, task_pid_nr(tsk), address, regs->ip,
 			regs->sp, error_code);
+			print_vma_addr(" in ", regs->ip);
+			printk("\n");
 		}
 		tsk->thread.cr2 = address;
 		/* Kernel addresses are always protection faults */
diff --git a/arch/x86/mm/fault_64.c b/arch/x86/mm/fault_64.c
index b606bde..9ef0306 100644
--- a/arch/x86/mm/fault_64.c
+++ b/arch/x86/mm/fault_64.c
@@ -552,11 +552,13 @@ bad_area_nosemaphore:
 #ifdef CONFIG_X86_32
 			"%s%s[%d]: segfault at %lx ip %08lx sp %08lx error %lx",
 #else
-			"%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx\n",
+			"%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx",
 #endif
 			task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 			tsk->comm, task_pid_nr(tsk), address, regs->ip,
 			regs->sp, error_code);
+			print_vma_addr(" in ", regs->ip);
+			printk("\n");
 		}
 
 		tsk->thread.cr2 = address;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1897ca2..3c22d97 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1146,6 +1146,7 @@ extern int randomize_va_space;
 #endif
 
 const char * arch_vma_name(struct vm_area_struct *vma);
+void print_vma_addr(char *prefix, unsigned long rip);
 
 struct page *sparse_mem_map_populate(unsigned long pnum, int nid);
 pgd_t *vmemmap_pgd_populate(unsigned long addr, int node);
diff --git a/mm/memory.c b/mm/memory.c
index 673ebbf..d902d0e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2754,3 +2754,34 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
 
 	return buf - old_buf;
 }
+
+/*
+ * Print the name of a VMA.
+ */
+void print_vma_addr(char *prefix, unsigned long ip)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+
+	down_read(&mm->mmap_sem);
+	vma = find_vma(mm, ip);
+	if (vma && vma->vm_file) {
+		struct file *f = vma->vm_file;
+		char *buf = (char *)__get_free_page(GFP_KERNEL);
+		if (buf) {
+			char *p, *s;
+
+			p = d_path(f->f_dentry, f->f_vfsmnt, buf, PAGE_SIZE);
+			if (IS_ERR(p))
+				p = "?";
+			s = strrchr(p, '/');
+			if (s)
+				p = s+1;
+			printk("%s%s[%lx+%lx]", prefix, p,
+					vma->vm_start,
+					vma->vm_end - vma->vm_start);
+			free_page((unsigned long)buf);
+		}
+	}
+	up_read(&current->mm->mmap_sem);
+}