Merge branches 'work.misc' and 'work.dcache' of git://git.kernel.org/pub/scm/linux...

[sfrench/cifs-2.6.git] / arch / x86 / kernel / head_64.S

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 48385c1074a57374223ae18e868c4d6671b33454..15ebc2fc166e66c954106ce7c7db3d73d377adae 100644 (file)
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -235,7 +235,7 @@ ENTRY(secondary_startup_64)
         *              address given in m16:64.
         */
        pushq   $.Lafter_lret   # put return address on stack for unwinder
-       xorq    %rbp, %rbp      # clear frame pointer
+       xorl    %ebp, %ebp      # clear frame pointer
        movq    initial_code(%rip), %rax
        pushq   $__KERNEL_CS    # set correct cs
        pushq   %rax            # target address in negative space
@@ -399,8 +399,13 @@ NEXT_PAGE(level3_ident_pgt)
        .quad   level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
        .fill   511, 8, 0
 NEXT_PAGE(level2_ident_pgt)
-       /* Since I easily can, map the first 1G.
+       /*
+        * Since I easily can, map the first 1G.
         * Don't set NX because code runs from these pages.
+        *
+        * Note: This sets _PAGE_GLOBAL despite whether
+        * the CPU supports it or it is enabled.  But,
+        * the CPU should ignore the bit.
         */
        PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
 #else
@@ -431,6 +436,10 @@ NEXT_PAGE(level2_kernel_pgt)
         * (NOTE: at +512MB starts the module area, see MODULES_VADDR.
         *  If you want to increase this then increase MODULES_VADDR
         *  too.)
+        *
+        *  This table is eventually used by the kernel during normal
+        *  runtime.  Care must be taken to clear out undesired bits
+        *  later, like _PAGE_RW or _PAGE_GLOBAL in some cases.
         */
        PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
                KERNEL_IMAGE_SIZE/PMD_SIZE)