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Fix jmp im on x86_64 when executing 32-bit code

PATCH In review Alexander Graf 2 participants 2 messages Dec 9, 2008 – Dec 10, 2008

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Alexander Graf

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#0 lore raw

PATCH 1/1 Fix jmp im on x86_64 when executing 32-bit code

When running grub-install (32-bit) on an x86_64 Linux system in qemu, it hangs on a pagefault forever, because an integer overflow occurs on the IP on "jmp im". This patch masks overflows for 32 bit IPs on a 64 bit system, just like it is done for 16 bit IPs already.

Using this patch, x86_64 openSUSE installation works again.

Signed-off-by Alexander Graf <[email protected]>
Signed-off-by Kevin Wolf <[email protected]>
translate.c +2 -0
Index: target-i386/translate.c
===================================================================
@@ -6165,6 +6165,8 @@
         tval += s->pc - s->cs_base;
         if (s->dflag == 0)
             tval &= 0xffff;
+	else if(!CODE64(s))
+            tval &= 0xffffffff;
         gen_jmp(s, tval);
         break;
     case 0xea: /* ljmp im */
#1 lore raw
Quoted 11 lines · Alexander Graf

When running grub-install (32-bit) on an x86_64 Linux system in qemu, it hangs on a pagefault forever, because an integer overflow occurs on the IP on "jmp im". This patch masks overflows for 32 bit IPs on a 64 bit system, just like it is done for 16 bit IPs already.

Using this patch, x86_64 openSUSE installation works again.

Signed-off-by Alexander Graf <[email protected]>
Signed-off-by Kevin Wolf <[email protected]>

Thanks for your great work, it is something broken for a long time, and it is nice to see that fixed. I have applied the patch to the SVN.

Quoted 13 lines

Index: target-i386/translate.c
===================================================================

translate.c +2 -0
@@ -6165,6 +6165,8 @@
         tval += s->pc - s->cs_base;
         if (s->dflag == 0)
             tval &= 0xffff;
+	else if(!CODE64(s))
+            tval &= 0xffffffff;
         gen_jmp(s, tval);
         break;
     case 0xea: /* ljmp im */
Signature · 4 lines
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   [email protected]         | [email protected]
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