[prefix] Use stack rather than %ebp as temporary storage area

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/arch/i386/prefix/libprefix.S b/src/arch/i386/prefix/libprefix.S
index 77151a67e0bb75a63d468f29d0f93244cf6ed3bb..ae3db32a666853de0114a8720175a83d725dfc43 100644 (file)
--- a/src/arch/i386/prefix/libprefix.S
+++ b/src/arch/i386/prefix/libprefix.S
@@ -661,8 +661,8 @@ install_prealloc:
        pushw   %cs
        popw    %ds
 
-       /* Copy decompression temporary area physical address to %ebp */
-       movl    %edi, %ebp
+       /* Save decompression temporary area physical address */
+       pushl   %edi
 
        /* Install .text16.early */
        progress "  .text16.early\n"
@@ -747,6 +747,9 @@ payload_death_message:
        /* Set up %ds for access to .data16 */
        movw    %bx, %ds
 
+       /* Restore decompression temporary area physical address */
+       popl    %edi
+
 #ifdef KEEP_IT_REAL
        /* Initialise libkir */
        movw    %ax, (init_libkir_vector+2)
@@ -754,7 +757,7 @@ payload_death_message:
 #else
        /* Find a suitable decompression temporary area, if none specified */
        pushl   %eax
-       testl   %ebp, %ebp
+       testl   %edi, %edi
        jnz     1f
        /* Use INT 15,88 to find the highest available address via INT
         * 15,88.  This limits us to around 64MB, which should avoid
@@ -762,14 +765,14 @@ payload_death_message:
         */
        movb    $0x88, %ah
        int     $0x15
-       movw    %ax, %bp
-       addl    $0x400, %ebp
-       subl    $_textdata_memsz_kb, %ebp
-       shll    $10, %ebp
+       movw    %ax, %di
+       addl    $0x400, %edi
+       subl    $_textdata_memsz_kb, %edi
+       shll    $10, %edi
        /* Sanity check: if we have ended up below 1MB, use 1MB */
-       cmpl    $0x100000, %ebp
+       cmpl    $0x100000, %edi
        jae     1f
-       movl    $0x100000, %ebp
+       movl    $0x100000, %edi
 1:     popl    %eax
 
        /* Install .text and .data to temporary area in high memory,
@@ -777,15 +780,15 @@ payload_death_message:
         * properly.
         */
        progress "  .textdata\n"
-       movl    %ebp, %edi
+       pushl   %edi
        movl    $_textdata_filesz, %ecx
        movl    $_textdata_memsz, %edx
        call    install_block
+       popl    %edi
 
        /* Initialise librm at current location */
        progress "  init_librm\n"
        movw    %ax, (init_librm_vector+2)
-       movl    %ebp, %edi
        lcall   *init_librm_vector
 
        /* Skip relocation if CF was set on entry */