Changeset 0b749a3 in mainline for kernel/arch/amd64/src/asm.S

Timestamp:

2010-11-22T15:39:53Z (13 years ago)

Author:

Vojtech Horky <vojtechhorky@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

0eddb76, aae339e9

Parents:

9a1d8ab (diff), 8cd1aa5e (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge development/ changes

File:

• kernel/arch/amd64/src/asm.S (modified) (7 diffs)

kernel/arch/amd64/src/asm.S

@@ -95 +95 @@
 memcpy_from_uspace_failover_address:
 memcpy_to_uspace_failover_address:
-        xorq %rax, %rax         /* return 0, failure */
+        xorl %eax, %eax         /* return 0, failure */
         ret
 
@@ -143 +143 @@
 
 set_efer_flag:
-        movq $0xc0000080, %rcx
+        movl $0xc0000080, %ecx
         rdmsr
         btsl %edi, %eax
@@ -150 +150 @@
 
 read_efer_flag:
-        movq $0xc0000080, %rcx
+        movl $0xc0000080, %ecx
         rdmsr
         ret
@@ -243 +243 @@
          * Stop stack traces here if we came from userspace.
          */
-        xorq %rdx, %rdx
-        cmpq $(gdtselector(KTEXT_DES)), ISTATE_OFFSET_CS(%rsp)
+        xorl %edx, %edx
+        cmpq $(GDT_SELECTOR(KTEXT_DES)), ISTATE_OFFSET_CS(%rsp)
         cmovnzq %rdx, %rbp
 
@@ -386 +386 @@
         movq ISTATE_OFFSET_RSP(%rsp), %rsp
 
+        /*
+         * Clear the rest of the scratch registers to prevent information leak.
+         * The 32-bit XOR on the low GPRs actually clears the entire 64-bit
+         * register and the instruction is shorter.
+         */
+        xorl %edx, %edx
+        xorl %esi, %esi
+        xorl %edi, %edi
+        xorq %r8, %r8
+        xorq %r9, %r9
+        xorq %r10, %r10
+
         sysretq
 
@@ -413 +425 @@
         movq %rdi, %rsi
         movq $(PA2KA(0xb8000)), %rdi  /* base of EGA text mode memory */
-        xorq %rax, %rax
+        xorl %eax, %eax
         
         /* Read bits 8 - 15 of the cursor address */
@@ -493 +505 @@
                 movq $(PA2KA(0xb80a0)), %rsi
                 movq $(PA2KA(0xb8000)), %rdi
-                movq $480, %rcx
+                movl $480, %ecx
                 rep movsq
                 
                 /* Clear the 24th row */
-                xorq %rax, %rax
-                movq $20, %rcx
+                xorl %eax, %eax
+                movl $20, %ecx
                 rep stosq