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

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


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@16204
This commit is contained in:
Julian Seward
2017-01-20 09:58:15 +00:00
parent 34b98bc823
commit f9e2cc163f
1 changed files with 32 additions and 6 deletions
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38
coregrind/m_syswrap/syswrap-x86-linux.c
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@@ -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 );
}