reloc() is not called according to cdecl calling convention.
This makes confusion and does not scale well for more arguments.
And patch adding multiboot2 protocol support have to pass 3
arguments instead of 2. Hence, move reloc() call to cdecl
calling convention.
I add push %ebp/mov %esp,%ebp/leave instructions here. Though they
are not strictly needed in this patch. However, then assembly code
in patch adding multiboot2 protocol support is easier to read.
Suggested-by: Jan Beulich <jbeul...@suse.com>
Signed-off-by: Daniel Kiper <daniel.ki...@oracle.com>
---
v3 - suggestions/fixes:
- simplify assembly in xen/arch/x86/boot/reloc.c file
(suggested by Jan Beulich),
- reorder arguments for reloc() call from xen/arch/x86/boot/head.S
(suggested by Jan Beulich),
- improve commit message
(suggested by Jan Beulich).
---
xen/arch/x86/boot/head.S | 4 +++-
xen/arch/x86/boot/reloc.c | 18 ++++++++++++++----
2 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 32a54a0..28ac721 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -119,8 +119,10 @@ __start:
/* Save the Multiboot info struct (after relocation) for later use. */
mov $sym_phys(cpu0_stack)+1024,%esp
- push %ebx
+ push %eax /* Boot trampoline address. */
+ push %ebx /* Multiboot information address. */
call reloc
+ add $8,%esp /* Remove reloc() args from stack. */
mov %eax,sym_phys(multiboot_ptr)
/* Initialize BSS (no nasty surprises!). */
diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c
index 63045c0..006f41d 100644
--- a/xen/arch/x86/boot/reloc.c
+++ b/xen/arch/x86/boot/reloc.c
@@ -10,15 +10,25 @@
* Keir Fraser <k...@xen.org>
*/
-/* entered with %eax = BOOT_TRAMPOLINE */
+/*
+ * This entry point is entered from xen/arch/x86/boot/head.S with:
+ * - 0x4(%esp) = MULTIBOOT_INFORMATION_ADDRESS,
+ * - 0x8(%esp) = BOOT_TRAMPOLINE_ADDRESS.
+ */
asm (
" .text \n"
" .globl _start \n"
"_start: \n"
+ " push %ebp \n"
+ " mov %esp,%ebp \n"
" call 1f \n"
- "1: pop %ebx \n"
- " mov %eax,alloc-1b(%ebx) \n"
- " jmp reloc \n"
+ "1: pop %ecx \n"
+ " mov 0xc(%ebp),%eax \n"
+ " mov %eax,alloc-1b(%ecx) \n"
+ " push 0x8(%ebp) \n"
+ " call reloc \n"
+ " leave \n"
+ " ret \n"
);
/*
--
1.7.10.4
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