thejh

# perf stat -e task-clock:u -e cycles:u -e instructions:u -e branches:u -e branch-misses:u -e dTLB-loads:u -e dTLB-load-misses:u -e dtlb_load_misses.walk_active:u ./spec_test map

 Performance counter stats for './spec_test map':

          1,150.38 msec task-clock:u                     #    1.000 CPUs utilized          
     5,370,185,772      cycles:u                         #    4.668 GHz                    
     1,331,717,669      instructions:u                   #    0.25  insn per cycle         
       307,326,910      branches:u                       #  267.153 M/sec                  
       102,502,300      branch-misses:u                  #   33.35% of all branches        
       102,427,183      dTLB-loads                       #   89.038 M/sec                  

thejh

--- memtester-orig/memtester-4.3.0/tests.c	2012-06-09 23:45:22.000000000 +0200
+++ memtester-4.3.0/tests.c	2018-06-24 18:08:03.194020598 +0200
@@ -11,14 +11,17 @@
  * This file contains the functions for the actual tests, called from the
  * main routine in memtester.c.  See other comments in that file.
  *
  */
 
+#define _GNU_SOURCE
 #include <sys/types.h>

thejh

~/tmp/pdf$ cat localtime_hack.c 
#include <time.h>

__attribute__((constructor)) static void localtime_hack(void) {
  time_t t = {0};
  localtime(&t);
}
~/tmp/pdf$ gcc -shared -fPIC -o localtime_hack.so localtime_hack.c 
~/tmp/pdf$ LD_BIND_NOW=1 LD_PRELOAD=./localtime_hack.so strace -f -e trace='!write,pread64,brk' pdftoppm test.pdf test.png 2>&1 | grep -A10000000 'open.*test\.pdf'
openat(AT_FDCWD, "test.pdf", O_RDONLY)  = 3

thejh

From 0bc2bc09d4c23cc5b48cea4bc2fb926a1fa72598 Mon Sep 17 00:00:00 2001
From: Jann Horn <jannh@google.com>
Date: Fri, 12 Apr 2019 16:13:30 +0200
Subject: [PATCH] objtool: Handle multiply-referenced and
 out-of-order-referenced jump tables

With clang from git master, code can be generated where a function contains
two indirect jump instructions that use the same switch table. To deal with
this case and similar ones properly, convert the switch table parsing to
use two passes:

thejh

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 957dfb693ecc..251ed2ca3f04 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1673,9 +1673,26 @@ ENTRY(rewind_stack_do_exit)
        /* Prevent any naive code from trying to unwind to our caller. */
        xorl    %ebp, %ebp
 
+       movq    %rdi, %r14
+

thejh

import os
import struct

# flags are encoded into chunk size
FLAGS_MASK = 0x7
PAGEMAP_PRESENT = 1<<63
PAGEMAP_SWAPPED = 1<<62

main_arena = gdb.parse_and_eval('&main_arena')
bins_per_arena = int(gdb.parse_and_eval(

thejh

// small stack memory usage experiment
// written by Jann Horn

#include <stdint.h>
#include <sys/ptrace.h>
#include <sys/user.h>
#include <fcntl.h>
#include <err.h>
#include <unistd.h>
#include <stdlib.h>

thejh

0x0 Twux 0x7aa7000
    0x0 Twux 0x8b4bf000
        0x400000 Twux 0x77c9000
            0x400000 P-ux 0x11f46000
        0x600000 Twux 0x72da000
            0x600000 P-u- 0x11f47000L
            0x601000 Pwu- 0x11ec8000L
        0x1e00000 Twux 0x79fb000
            0x1f13000 Pwu- 0x11f7a000L
            0x1f14000 Pwu- 0x11f7b000L

thejh

$ ./perf_sample_regs_intr_demo 
data_head is at ff0
rax=0xffffffffffffffff rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0x4005b0
rax=0xfffffffffffffff7 rbp=0xffffa5fc43efff48 rsp=0xffffa5fc43efff28 rip=0xffffffff97c55f1d
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce18
rax=0xffff8fc3ba3b79c0 rbp=0xffffa5fc43efff00 rsp=0xffffa5fc43effef0 rip=0xffffffff97c745c9
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce18
rax=0x0 rbp=0xffffa5fc43efff00 rsp=0xffffa5fc43effef8 rip=0xffffffff97c75049
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce15
rax=0xffffffffffffffff rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040c0 rip=0x4007d5

thejh

init	 root allcaps
ueventd	 root allcaps
logd	 CAP_AUDIT_CONTROL CAP_SYSLOG
qseecomd	 CAP_NET_RAW CAP_SYS_RAWIO CAP_SYS_ADMIN
qseecomd	 CAP_NET_RAW CAP_SYS_RAWIO CAP_SYS_ADMIN
debuggerd	 root allcaps
debuggerd64	 root allcaps
vold	 root allcaps
debuggerd64:sig	 root allcaps
debuggerd:sig	 root allcaps