commit c7bcd1f2ee2d466fb556bfc2b33c5ab039b0898d

Author: sewardj <sewardj@a5019735-40e9-0310-863c-91ae7b9d1cf9>

Date:   Fri Jan 20 09:58:15 2017 +0000

    x86-linux: Initialize x86 system GDT on first use.  Bug 344139 comment 3.

    Patch from Sebastian Lackner, sebastian@fds-team.de.

    git-svn-id: svn://svn.valgrind.org/valgrind/trunk@16204 a5019735-40e9-0310-863c-91ae7b9d1cf9

diff --git a/coregrind/m_syswrap/syswrap-x86-linux.c b/coregrind/m_syswrap/syswrap-x86-linux.c

index f8c4eb4..2f879d8 100644

--- a/coregrind/m_syswrap/syswrap-x86-linux.c

+++ b/coregrind/m_syswrap/syswrap-x86-linux.c

@@ -294,11 +294,37 @@ void translate_to_hw_format ( /* IN  */ vki_modify_ldt_t* inn,

    out->LdtEnt.Words.word2 = entry_2;

 }

-/* Create a zeroed-out GDT. */

-static VexGuestX86SegDescr* alloc_zeroed_x86_GDT ( void )

+/* Create initial GDT. */

+static VexGuestX86SegDescr* alloc_system_x86_GDT ( void )

 {

    Int nbytes = VEX_GUEST_X86_GDT_NENT * sizeof(VexGuestX86SegDescr);

-   return VG_(calloc)("di.syswrap-x86.azxG.1", nbytes, 1);

+   VexGuestX86SegDescr* gdt = VG_(calloc)("di.syswrap-x86.azxG.1", nbytes, 1);

+   vki_modify_ldt_t info;

+   UShort seg;

+

+   VG_(memset)(&info, 0, sizeof(info));

+   info.entry_number    = 0;

+   info.base_addr       = 0;

+   info.limit           = 0xfffff;

+   info.seg_32bit       = 1;

+   info.contents        = 0;

+   info.read_exec_only  = 0;

+   info.limit_in_pages  = 1;

+   info.seg_not_present = 0;

+   info.useable         = 0;

+   info.reserved        = 0;

+

+   asm volatile("movw %%ds, %0" : : "m" (seg));

+   if (!(seg & 4)) translate_to_hw_format(&info, &gdt[seg >> 3], 0);

+   asm volatile("movw %%ss, %0" : : "m" (seg));

+   if (!(seg & 4)) translate_to_hw_format(&info, &gdt[seg >> 3], 0);

+

+   info.contents        = 2;

+

+   asm volatile("movw %%cs, %0" : : "m" (seg));

+   if (!(seg & 4)) translate_to_hw_format(&info, &gdt[seg >> 3], 0);

+

+   return gdt;

 }

 /* Create a zeroed-out LDT. */

@@ -505,7 +531,7 @@ SysRes ML_(x86_sys_set_thread_area) ( ThreadId tid, vki_modify_ldt_t* info )

    /* If the thread doesn't have a GDT, allocate it now. */

    if (!gdt) {

-      gdt = alloc_zeroed_x86_GDT();

+      gdt = alloc_system_x86_GDT();

       VG_(threads)[tid].arch.vex.guest_GDT = (HWord)gdt;

    }

@@ -564,7 +590,7 @@ static SysRes sys_get_thread_area ( ThreadId tid, vki_modify_ldt_t* info )

    /* If the thread doesn't have a GDT, allocate it now. */

    if (!gdt) {

-      gdt = alloc_zeroed_x86_GDT();

+      gdt = alloc_system_x86_GDT();

       VG_(threads)[tid].arch.vex.guest_GDT = (HWord)gdt;

    }

@@ -616,7 +642,7 @@ void ML_(x86_setup_LDT_GDT) ( /*OUT*/ ThreadArchState *child,

    child->vex.guest_GDT = (HWord)NULL;

    if (parent->vex.guest_GDT != (HWord)NULL) {

-      child->vex.guest_GDT = (HWord)alloc_zeroed_x86_GDT();

+      child->vex.guest_GDT = (HWord)alloc_system_x86_GDT();

       copy_GDT_from_to( (VexGuestX86SegDescr*)parent->vex.guest_GDT,

                         (VexGuestX86SegDescr*)child->vex.guest_GDT );

    }

commit 5f4041b376f7465cd108ad4d1696b0b8a603a175

Author: sewardj <sewardj@8f6e269a-dfd6-0310-a8e1-e2731360e62c>

Date:   Fri Jan 20 10:01:42 2017 +0000

    x86: Recognize the SS segment prefix on x86.  Bug 344139 comment 4.

    Patch from Sebastian Lackner, sebastian@fds-team.de.

    git-svn-id: svn://svn.valgrind.org/vex/trunk@3299 8f6e269a-dfd6-0310-a8e1-e2731360e62c

diff --git a/VEX/priv/guest_x86_toIR.c b/VEX/priv/guest_x86_toIR.c

index de09d3a..234d68e 100644

--- a/VEX/priv/guest_x86_toIR.c

+++ b/VEX/priv/guest_x86_toIR.c

@@ -1409,6 +1409,7 @@ const HChar* sorbTxt ( UChar sorb )

       case 0x26: return "%es:";

       case 0x64: return "%fs:";

       case 0x65: return "%gs:";

+      case 0x36: return "%ss:";

       default: vpanic("sorbTxt(x86,guest)");

    }

 }

@@ -1433,6 +1434,7 @@ IRExpr* handleSegOverride ( UChar sorb, IRExpr* virtual )

       case 0x26: sreg = R_ES; break;

       case 0x64: sreg = R_FS; break;

       case 0x65: sreg = R_GS; break;

+      case 0x36: sreg = R_SS; break;

       default: vpanic("handleSegOverride(x86,guest)");

    }

@@ -8101,7 +8103,7 @@ DisResult disInstr_X86_WRK (

    Int sz = 4;

    /* sorb holds the segment-override-prefix byte, if any.  Zero if no

-      prefix has been seen, else one of {0x26, 0x3E, 0x64, 0x65}

+      prefix has been seen, else one of {0x26, 0x36, 0x3E, 0x64, 0x65}

       indicating the prefix.  */

    UChar sorb = 0;

@@ -8255,6 +8257,7 @@ DisResult disInstr_X86_WRK (

          case 0x26: /* %ES: */

          case 0x64: /* %FS: */

          case 0x65: /* %GS: */

+         case 0x36: /* %SS: */

             if (sorb != 0) 

                goto decode_failure; /* only one seg override allowed */

             sorb = pre;

@@ -8274,9 +8277,6 @@ DisResult disInstr_X86_WRK (

             }

             break;

          }

-         case 0x36: /* %SS: */

-            /* SS override cases are not handled */

-            goto decode_failure;

          default: 

             goto not_a_prefix;

       }