[Qemu-devel] [PATCH 14/17] Revived GUEST_BASE support for usermode emulation targets.

[riku . voipio]

From: Riku Voipio <address@hidden>

From: Mika Westerberg <address@hidden>

- Now GUEST_BASE is dynamic and can be set from command line.
- Qemu checks /proc/sys/vm/mmap_min_addr and sets GUEST_BASE
  if needed.
- Code generation supports GUEST_BASE for i386 and x86_64 hosts.

Signed-off-by: Riku Voipio <address@hidden>
---
 configure               |    9 ++++++
 cpu-all.h               |    6 +++-
 linux-user/elfload.c    |   24 ++++++++++++++++++
 linux-user/main.c       |   63 +++++++++++++++++++++++++++++++++++++++++++++++
 linux-user/qemu.h       |    3 ++
 linux-user/syscall.c    |    2 +
 tcg/i386/tcg-target.c   |   12 +++++++++
 tcg/x86_64/tcg-target.c |   12 +++++++++
 8 files changed, 130 insertions(+), 1 deletions(-)

diff --git a/configure b/configure
index 5c62c59..8b0a378 100755
--- a/configure
+++ b/configure
@@ -176,6 +176,7 @@ softmmu="yes"
 linux_user="no"
 darwin_user="no"
 bsd_user="no"
+guest_base="no"
 build_docs="no"
 uname_release=""
 curses="yes"
@@ -437,6 +438,8 @@ for opt do
   ;;
   --enable-bsd-user) bsd_user="yes"
   ;;
+  --enable-guest-base) guest_base="yes"
+  ;;
   --enable-uname-release=*) uname_release="$optarg"
   ;;
   --sparc_cpu=*)
@@ -570,6 +573,8 @@ echo "  --enable-darwin-user     enable all darwin usermode 
emulation targets"
 echo "  --disable-darwin-user    disable all darwin usermode emulation targets"
 echo "  --enable-bsd-user        enable all BSD usermode emulation targets"
 echo "  --disable-bsd-user       disable all BSD usermode emulation targets"
+echo "  --enable-guest-base      enable GUEST_BASE support for usermode"
+echo "                           emulation targets"
 echo "  --fmod-lib               path to FMOD library"
 echo "  --fmod-inc               path to FMOD includes"
 echo "  --oss-lib                path to OSS library"
@@ -1202,6 +1207,7 @@ echo "Documentation     $build_docs"
 [ ! -z "$uname_release" ] && \
 echo "uname -r          $uname_release"
 echo "NPTL support      $nptl"
+echo "GUEST_BASE        $guest_base"
 echo "vde support       $vde"
 echo "AIO support       $aio"
 echo "Install blobs     $blobs"
@@ -1848,6 +1854,9 @@ if test "$target_user_only" = "yes" -a "$elfload32" = 
"yes"; then
   echo "TARGET_HAS_ELFLOAD32=yes" >> $config_mak
   echo "#define TARGET_HAS_ELFLOAD32 1" >> $config_h
 fi
+if test "$target_user_only" = "yes" -a "$guest_base" = "yes"; then
+  echo "#define CONFIG_USE_GUEST_BASE 1" >> $config_h
+fi
 if test "$target_bsd_user" = "yes" ; then
   echo "CONFIG_BSD_USER=yes" >> $config_mak
   echo "#define CONFIG_BSD_USER 1" >> $config_h
diff --git a/cpu-all.h b/cpu-all.h
index 366f47e..0e6efae 100644
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -629,8 +629,12 @@ static inline void stfq_be_p(void *ptr, float64 v)
 /* On some host systems the guest address space is reserved on the host.
  * This allows the guest address space to be offset to a convenient location.
  */
-//#define GUEST_BASE 0x20000000
+#if defined(CONFIG_USE_GUEST_BASE)
+extern unsigned long guest_base;
+#define GUEST_BASE guest_base
+#else
 #define GUEST_BASE 0
+#endif
 
 /* All direct uses of g2h and h2g need to go away for usermode softmmu.  */
 #define g2h(x) ((void *)((unsigned long)(x) + GUEST_BASE))
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 6de30f4..ea012e0 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -1337,6 +1337,30 @@ int load_elf_binary(struct linux_binprm * bprm, struct 
target_pt_regs * regs,
     info->mmap = 0;
     elf_entry = (abi_ulong) elf_ex.e_entry;
 
+#if defined(CONFIG_USE_GUEST_BASE)
+    /*
+     * In case where user has not explicitly set the guest_base, we
+     * probe here that should we set it automatically.
+     */
+    if (guest_base == 0) {
+        /*
+         * Go through ELF program header table and find out whether
+        * any of the segments drop below our current mmap_min_addr and
+         * in that case set guest_base to corresponding address.
+         */
+        for (i = 0, elf_ppnt = elf_phdata; i < elf_ex.e_phnum;
+            i++, elf_ppnt++) {
+            if (elf_ppnt->p_type != PT_LOAD)
+                continue;
+            if (HOST_PAGE_ALIGN(elf_ppnt->p_vaddr) < mmap_min_addr) {
+                guest_base = HOST_PAGE_ALIGN(mmap_min_addr);
+                qemu_log("setting guest_base=0x%lx\n", guest_base);
+                break;
+            }
+        }
+    }
+#endif /* CONFIG_USE_GUEST_BASE */
+
     /* Do this so that we can load the interpreter, if need be.  We will
        change some of these later */
     info->rss = 0;
diff --git a/linux-user/main.c b/linux-user/main.c
index 40308aa..912d68d 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -39,6 +39,11 @@
 
 char *exec_path;
 
+#if defined(CONFIG_USE_GUEST_BASE)
+unsigned long mmap_min_addr = 0;
+unsigned long guest_base = 0;
+#endif
+
 static const char *interp_prefix = CONFIG_QEMU_PREFIX;
 const char *qemu_uname_release = CONFIG_UNAME_RELEASE;
 
@@ -2214,6 +2219,9 @@ static void usage(void)
            "-E var=value      sets/modifies targets environment variable(s)\n"
            "-U var            unsets targets environment variable(s)\n"
            "-0 argv0          forces target process argv[0] to be argv0\n"
+#if defined(CONFIG_USE_GUEST_BASE)
+           "-B address        set guest_base address to address\n"
+#endif
            "\n"
            "Debug options:\n"
            "-d options   activate log (logfile=%s)\n"
@@ -2229,6 +2237,15 @@ static void usage(void)
            "    -E var1=val2 -E var2=val2 -U LD_PRELOAD -U LD_DEBUG\n"
            "Note that if you provide several changes to single variable\n"
            "last change will stay in effect.\n"
+#if defined(CONFIG_USE_GUEST_BASE)
+           "\n"
+           "You can use -B option to load target binary into different\n"
+           "address that is specified in elf headers.  This can be useful\n"
+           "when target binary would be loaded to low addresses and\n"
+           "/proc/sys/vm/mmap_min_addr is set to higher.  For example\n"
+           "     qemu-" TARGET_ARCH " -B 0x100000 ...\n"
+           "loads target binary starting from the first meg.\n"
+#endif
            ,
            TARGET_ARCH,
            interp_prefix,
@@ -2365,6 +2382,10 @@ int main(int argc, char **argv, char **envp)
 #endif
                 exit(1);
             }
+#if defined(CONFIG_USE_GUEST_BASE)
+        } else if (!strcmp(r, "B")) {
+           guest_base = strtol(argv[optind++], NULL, 0);
+#endif
         } else if (!strcmp(r, "drop-ld-preload")) {
             (void) envlist_unsetenv(envlist, "LD_PRELOAD");
         } else if (!strcmp(r, "strace")) {
@@ -2438,6 +2459,36 @@ int main(int argc, char **argv, char **envp)
     target_environ = envlist_to_environ(envlist, NULL);
     envlist_free(envlist);
 
+#if defined(CONFIG_USE_GUEST_BASE)
+    /*
+     * Now that page sizes are configured in cpu_init() we can do
+     * proper page alignment for guest_base.
+     */
+    guest_base = HOST_PAGE_ALIGN(guest_base);
+
+    /*
+     * Read in mmap_min_addr kernel parameter and check
+     * whether it is set to some value > 0.  This value is used
+     * later on when doing mmap(2)s to calculate where guest_base
+     * is to set, if needed.
+     *
+     * When user has explicitly set the quest base, we skip this
+     * test.
+     */
+    if (guest_base == 0) {
+        FILE *fp;
+
+        if ((fp = fopen("/proc/sys/vm/mmap_min_addr", "r")) != NULL) {
+            unsigned long tmp;
+            if (fscanf(fp, "%lu", &tmp) == 1) {
+                mmap_min_addr = tmp;
+                qemu_log("kernel mmap_min_addr=%lu\n", mmap_min_addr);
+            }
+            fclose(fp);
+        }
+    }
+#endif /* CONFIG_USE_GUEST_BASE */
+
     /*
      * Prepare copy of argv vector for target.
      */
@@ -2478,6 +2529,18 @@ int main(int argc, char **argv, char **envp)
     free(target_environ);
 
     if (qemu_log_enabled()) {
+#if defined(CONFIG_USE_GUEST_BASE)
+        if (guest_base > 0) {
+            qemu_log("guest_base is set to 0x%lx\n", guest_base);
+            qemu_log(
+                "==========================================================\n"
+                "Note that all target addresses below are given in target\n"
+                "address space which is different from host by guest_base.\n"
+                "For example: target address 0x%x becomes 0x%x and so on.\n"
+                "==========================================================\n",
+                (uintptr_t)0x8000, (uintptr_t)g2h(0x8000));
+        }
+#endif
         log_page_dump();
 
         qemu_log("start_brk   0x" TARGET_ABI_FMT_lx "\n", info->start_brk);
diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index 94ae333..5b9abc7 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -126,6 +126,9 @@ typedef struct TaskState {
 extern char *exec_path;
 void init_task_state(TaskState *ts);
 extern const char *qemu_uname_release;
+#if defined(CONFIG_USE_GUEST_BASE)
+extern unsigned long mmap_min_addr;
+#endif
 
 /* ??? See if we can avoid exposing so much of the loader internals.  */
 /*
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index c6b0b74..ef2bf55 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -2413,6 +2413,8 @@ static inline abi_long do_shmat(int shmid, abi_ulong 
shmaddr, int shmflg,
         }
     }
 
+    *raddr = h2g(*raddr);
+
     mmap_unlock();
     return 0;
 }
diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
index e0fd434..7cb51b5 100644
--- a/tcg/i386/tcg-target.c
+++ b/tcg/i386/tcg-target.c
@@ -560,6 +560,12 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg 
*args,
     /* add x(r1), r0 */
     tcg_out_modrm_offset(s, 0x03, r0, r1, offsetof(CPUTLBEntry, addend) - 
                          offsetof(CPUTLBEntry, addr_read));
+#elif defined(CONFIG_USE_GUEST_BASE)
+    /*
+     * Add guest_base to all loads.
+     */
+    tcg_out_mov(s, r0, addr_reg);    /* movl addr_reg, r0 */
+    tcg_out_addi(s, r0, GUEST_BASE); /* addl $GUEST_BASE, r0 */
 #else
     r0 = addr_reg;
 #endif
@@ -794,6 +800,12 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg 
*args,
     /* add x(r1), r0 */
     tcg_out_modrm_offset(s, 0x03, r0, r1, offsetof(CPUTLBEntry, addend) - 
                          offsetof(CPUTLBEntry, addr_write));
+#elif defined(CONFIG_USE_GUEST_BASE)
+    /*
+     * Add guest_base to all stores.
+     */
+    tcg_out_mov(s, r0, addr_reg);    /* movl addr_reg, r0 */
+    tcg_out_addi(s, r0, GUEST_BASE); /* addl $GUEST_BASE, r0 */
 #else
     r0 = addr_reg;
 #endif
diff --git a/tcg/x86_64/tcg-target.c b/tcg/x86_64/tcg-target.c
index 92f0733..204ab2a 100644
--- a/tcg/x86_64/tcg-target.c
+++ b/tcg/x86_64/tcg-target.c
@@ -605,6 +605,12 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg 
*args,
     /* add x(r1), r0 */
     tcg_out_modrm_offset(s, 0x03 | P_REXW, r0, r1, offsetof(CPUTLBEntry, 
addend) - 
                          offsetof(CPUTLBEntry, addr_read));
+#elif defined(CONFIG_USE_GUEST_BASE)
+    /*
+     * Add guest_base to all loads.
+     */
+    tcg_out_modrm(s, 0x8b | rexw, r0, addr_reg); /* movq addr_reg, r0 */
+    tcg_out_addi(s, r0, GUEST_BASE);             /* addq $GUEST_BASE, r0 */
 #else
     r0 = addr_reg;
 #endif    
@@ -776,6 +782,12 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg 
*args,
     /* add x(r1), r0 */
     tcg_out_modrm_offset(s, 0x03 | P_REXW, r0, r1, offsetof(CPUTLBEntry, 
addend) - 
                          offsetof(CPUTLBEntry, addr_write));
+#elif defined(CONFIG_USE_GUEST_BASE)
+    /*
+     * Add guest_base to all stores.
+     */
+    tcg_out_modrm(s, 0x8b | rexw, r0, addr_reg); /* movq addr_reg, r0 */
+    tcg_out_addi(s, r0, GUEST_BASE);             /* addq $GUEST_BASE, r0 */
 #else
     r0 = addr_reg;
 #endif
-- 
1.6.2.1