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-rw-r--r--kernels/linux-libre-xen/0007-x86-efi-Correct-EFI-boot-stub-use-of-code32_start.patch110
1 files changed, 110 insertions, 0 deletions
diff --git a/kernels/linux-libre-xen/0007-x86-efi-Correct-EFI-boot-stub-use-of-code32_start.patch b/kernels/linux-libre-xen/0007-x86-efi-Correct-EFI-boot-stub-use-of-code32_start.patch
new file mode 100644
index 000000000..898ee1543
--- /dev/null
+++ b/kernels/linux-libre-xen/0007-x86-efi-Correct-EFI-boot-stub-use-of-code32_start.patch
@@ -0,0 +1,110 @@
+From 720a9dbf61c88bd57d6f8198ed8ccb2bd4a6abd8 Mon Sep 17 00:00:00 2001
+From: Matt Fleming <matt@console-pimps.org>
+Date: Wed, 9 Apr 2014 10:33:49 +0200
+Subject: [PATCH 07/10] x86/efi: Correct EFI boot stub use of code32_start
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+code32_start should point at the start of the protected mode code, and
+*not* at the beginning of the bzImage. This is much easier to do in
+assembly so document that callers of make_boot_params() need to fill out
+code32_start.
+
+The fallout from this bug is that we would end up relocating the image
+but copying the image at some offset, resulting in what appeared to be
+memory corruption.
+
+Reported-by: Thomas Bächler <thomas@archlinux.org>
+Signed-off-by: Matt Fleming <matt.fleming@intel.com>
+---
+ arch/x86/boot/compressed/eboot.c | 5 +++--
+ arch/x86/boot/compressed/head_32.S | 14 ++++++++------
+ arch/x86/boot/compressed/head_64.S | 9 +++------
+ 3 files changed, 14 insertions(+), 14 deletions(-)
+
+diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
+index a7677ba..78cbb2d 100644
+--- a/arch/x86/boot/compressed/eboot.c
++++ b/arch/x86/boot/compressed/eboot.c
+@@ -425,6 +425,9 @@ void setup_graphics(struct boot_params *boot_params)
+ * Because the x86 boot code expects to be passed a boot_params we
+ * need to create one ourselves (usually the bootloader would create
+ * one for us).
++ *
++ * The caller is responsible for filling out ->code32_start in the
++ * returned boot_params.
+ */
+ struct boot_params *make_boot_params(void *handle, efi_system_table_t *_table)
+ {
+@@ -483,8 +486,6 @@ struct boot_params *make_boot_params(void *handle, efi_system_table_t *_table)
+ hdr->vid_mode = 0xffff;
+ hdr->boot_flag = 0xAA55;
+
+- hdr->code32_start = (__u64)(unsigned long)image->image_base;
+-
+ hdr->type_of_loader = 0x21;
+
+ /* Convert unicode cmdline to ascii */
+diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
+index 9116aac..f45ab7a 100644
+--- a/arch/x86/boot/compressed/head_32.S
++++ b/arch/x86/boot/compressed/head_32.S
+@@ -50,6 +50,13 @@ ENTRY(efi_pe_entry)
+ pushl %eax
+ pushl %esi
+ pushl %ecx
++
++ call reloc
++reloc:
++ popl %ecx
++ subl reloc, %ecx
++ movl %ecx, BP_code32_start(%eax)
++
+ sub $0x4, %esp
+
+ ENTRY(efi_stub_entry)
+@@ -63,12 +70,7 @@ ENTRY(efi_stub_entry)
+ hlt
+ jmp 1b
+ 2:
+- call 3f
+-3:
+- popl %eax
+- subl $3b, %eax
+- subl BP_pref_address(%esi), %eax
+- add BP_code32_start(%esi), %eax
++ movl BP_code32_start(%esi), %eax
+ leal preferred_addr(%eax), %eax
+ jmp *%eax
+
+diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
+index c5c1ae0..b10fa66 100644
+--- a/arch/x86/boot/compressed/head_64.S
++++ b/arch/x86/boot/compressed/head_64.S
+@@ -217,6 +217,8 @@ ENTRY(efi_pe_entry)
+ cmpq $0,%rax
+ je 1f
+ mov %rax, %rdx
++ leaq startup_32(%rip), %rax
++ movl %eax, BP_code32_start(%rdx)
+ popq %rsi
+ popq %rdi
+
+@@ -230,12 +232,7 @@ ENTRY(efi_stub_entry)
+ hlt
+ jmp 1b
+ 2:
+- call 3f
+-3:
+- popq %rax
+- subq $3b, %rax
+- subq BP_pref_address(%rsi), %rax
+- add BP_code32_start(%esi), %eax
++ movl BP_code32_start(%esi), %eax
+ leaq preferred_addr(%rax), %rax
+ jmp *%rax
+
+--
+1.9.2
+