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 74df55895c8c..89a690edf999 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 4eb751c60390..7347bb14e306 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 6f3bb287c702..270cfd483160 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 814801f4eb9e..911ed28afff8 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 13d295506a17..276863dc4bdd 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 b606bdefbb72..9ef0306efe9e 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 1897ca223eca..3c22d971afa7 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 673ebbf499c7..d902d0e25edc 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);
+}