|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v2 5/5] x86: Rollback relocation in case of EFI multiboot
In case EFI not multiboot rolling back relocation is done in
efi_arch_post_exit_boot, called by efi_start however this is
not done in multiboot code path.
Do it also for this path to make it work correctly.
Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
---
xen/arch/x86/boot/Makefile | 2 +-
xen/arch/x86/boot/efi-reloc-image.c | 40 ++++++++++++++
xen/arch/x86/boot/efi-reloc-image.h | 85 +++++++++++++++++++++++++++++
xen/arch/x86/boot/head.S | 44 ++++++++++++---
xen/arch/x86/efi/efi-boot.h | 64 ++--------------------
5 files changed, 168 insertions(+), 67 deletions(-)
create mode 100644 xen/arch/x86/boot/efi-reloc-image.c
create mode 100644 xen/arch/x86/boot/efi-reloc-image.h
---
Changes since v1:
- many style updates;
- split file for 32 bit relocation;
- reuse code from header avoiding duplication;
- add some more comment to assembly code;
diff --git a/xen/arch/x86/boot/Makefile b/xen/arch/x86/boot/Makefile
index 03d8ce3a9e..49792e0acf 100644
--- a/xen/arch/x86/boot/Makefile
+++ b/xen/arch/x86/boot/Makefile
@@ -1,6 +1,6 @@
obj-bin-y += head.o
-head-bin-objs := cmdline.o reloc.o
+head-bin-objs := cmdline.o reloc.o efi-reloc-image.o
nocov-y += $(head-bin-objs)
noubsan-y += $(head-bin-objs)
diff --git a/xen/arch/x86/boot/efi-reloc-image.c
b/xen/arch/x86/boot/efi-reloc-image.c
new file mode 100644
index 0000000000..b103e37cd7
--- /dev/null
+++ b/xen/arch/x86/boot/efi-reloc-image.c
@@ -0,0 +1,40 @@
+/*
+ * efi-reloc-image.c
+ *
+ * 32-bit flat memory-map routines for relocating back PE executable.
+ * This is done with paging disabled to avoid permission issues.
+ *
+ * Copyright (c) 2024, Citrix Systems, Inc.
+ */
+
+/*
+ * This entry point is entered from xen/arch/x86/boot/head.S with:
+ * - 0x04(%esp) = __XEN_VIRT_START - xen_phys_start
+ * - 0x0c(%esp) = xen_phys_start
+ * - 0x10(%esp) = __base_relocs_start
+ * - 0x14(%esp) = __base_relocs_end
+ */
+asm (
+ " .text \n"
+ " .globl _start \n"
+ "_start: \n"
+ " jmp reloc_pe_back \n"
+ );
+
+#include "defs.h"
+
+/* Do not patch page tables. */
+#define in_page_tables(v) false
+
+#define EFI_RELOC_IMAGE_EARLY 1
+#include "efi-reloc-image.h"
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/x86/boot/efi-reloc-image.h
b/xen/arch/x86/boot/efi-reloc-image.h
new file mode 100644
index 0000000000..999dd2d2c8
--- /dev/null
+++ b/xen/arch/x86/boot/efi-reloc-image.h
@@ -0,0 +1,85 @@
+/*
+ * efi-reloc-image.h
+ *
+ * Code for relocating back PE executable.
+ * This code is common between 64 bit and 32 bit.
+ *
+ * Copyright (c) 2024, Citrix Systems, Inc.
+ */
+
+#if EFI_RELOC_IMAGE_EARLY != 0 && EFI_RELOC_IMAGE_EARLY != 1
+#error EFI_RELOC_IMAGE_EARLY must be defined either 0 or 1
+#endif
+
+typedef struct pe_base_relocs {
+ uint32_t rva;
+ uint32_t size;
+ uint16_t entries[];
+} pe_base_relocs;
+
+#define PE_BASE_RELOC_ABS 0
+#define PE_BASE_RELOC_HIGHLOW 3
+#define PE_BASE_RELOC_DIR64 10
+
+#if EFI_RELOC_IMAGE_EARLY
+bool __stdcall
+#else
+static bool
+#endif
+reloc_pe_back(long long delta,
+ unsigned long xen_phys_start,
+ const pe_base_relocs *__base_relocs_start,
+ const pe_base_relocs *__base_relocs_end)
+{
+ const struct pe_base_relocs *base_relocs;
+
+ for ( base_relocs = __base_relocs_start; base_relocs < __base_relocs_end; )
+ {
+ unsigned int i = 0, n;
+
+ n = (base_relocs->size - sizeof(*base_relocs)) /
+ sizeof(*base_relocs->entries);
+
+ for ( ; i < n; ++i )
+ {
+ unsigned long addr = xen_phys_start + base_relocs->rva +
+ (base_relocs->entries[i] & 0xfff);
+
+ switch ( base_relocs->entries[i] >> 12 )
+ {
+ case PE_BASE_RELOC_ABS:
+ break;
+ case PE_BASE_RELOC_HIGHLOW:
+ if ( delta )
+ {
+ *(uint32_t *)addr += delta;
+ if ( in_page_tables(addr) )
+ *(uint32_t *)addr += xen_phys_start;
+ }
+ break;
+ case PE_BASE_RELOC_DIR64:
+ if ( delta )
+ {
+ *(uint64_t *)addr += delta;
+ if ( in_page_tables(addr) )
+ *(uint64_t *)addr += xen_phys_start;
+ }
+ break;
+ default:
+ return false;
+ }
+ }
+ base_relocs = (const void *)(base_relocs->entries + i + (i & 1));
+ }
+ return true;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 86805389f9..dd3600c14b 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -332,7 +332,8 @@ __efi64_mb2_start:
*/
and $~15,%rsp
- /* Save Multiboot2 magic on the stack. */
+ /* Save Multiboot2 magic on the stack for a later 32bit call */
+ shl $32, %rax
push %rax
/* Save EFI ImageHandle on the stack. */
@@ -363,11 +364,25 @@ __efi64_mb2_start:
/* Just pop an item from the stack. */
pop %rax
- /* Restore Multiboot2 magic. */
- pop %rax
+ /*
+ * Prepare stack for relocation call.
+ * Note that we are in 64bit mode but we are going to call a
+ * function in 32bit mode so the stack is not written with
+ * push instructions.
+ */
+ sub $16, %rsp
+ lea __base_relocs_end(%rip), %ecx
+ mov %ecx, 16(%rsp)
+ lea __base_relocs_start(%rip), %ecx
+ mov %ecx, 12(%rsp)
+ lea __image_base__(%rip), %esi
+ mov %esi, 8(%rsp)
+ movabs $__XEN_VIRT_START, %rcx
+ sub %rsi, %rcx
+ mov %rcx, (%rsp)
- /* Jump to trampoline_setup after switching CPU to x86_32 mode. */
- lea trampoline_setup(%rip),%r15
+ /* Jump to trampoline_efi_setup after switching CPU to x86_32 mode. */
+ lea trampoline_efi_setup(%rip), %r15
x86_32_switch:
mov %r15,%rdi
@@ -539,6 +554,17 @@ __start:
and $~(MULTIBOOT2_TAG_ALIGN-1),%ecx
jmp .Lmb2_tsize
+trampoline_efi_setup:
+ call reloc_pe_back
+ pop %eax
+
+ /* Calculate the load base address again, adjusting to sym_esi needs */
+ call 1f
+1: pop %esi
+ sub $sym_offs(1b), %esi
+
+ jmp trampoline_setup
+
trampoline_bios_setup:
/*
* Called on legacy BIOS platforms only.
@@ -867,8 +893,8 @@ trampoline_setup:
lret
/*
- * cmdline and reloc are written in C, and linked to be 32bit PIC with
- * entrypoints at 0 and using the stdcall convention.
+ * cmdline, reloc and reloc_pe_back are written in C, and linked to be
+ * 32bit PIC with entrypoints at 0 and using the stdcall convention.
*/
ALIGN
cmdline_parse_early:
@@ -878,6 +904,10 @@ cmdline_parse_early:
reloc:
.incbin "reloc.bin"
+ ALIGN
+reloc_pe_back:
+ .incbin "efi-reloc-image.bin"
+
.section .init.data, "aw", @progbits
ENTRY(trampoline_start)
diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index f282358435..4f473a287e 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -36,69 +36,15 @@ extern const intpte_t __page_tables_start[],
__page_tables_end[];
#define in_page_tables(v) ((intpte_t *)(v) >= __page_tables_start && \
(intpte_t *)(v) < __page_tables_end)
-#define PE_BASE_RELOC_ABS 0
-#define PE_BASE_RELOC_HIGHLOW 3
-#define PE_BASE_RELOC_DIR64 10
+#define EFI_RELOC_IMAGE_EARLY 0
+#include "../boot/efi-reloc-image.h"
-extern const struct pe_base_relocs {
- u32 rva;
- u32 size;
- u16 entries[];
-} __base_relocs_start[], __base_relocs_end[];
+extern pe_base_relocs __base_relocs_start[], __base_relocs_end[];
static void __init efi_arch_relocate_image(unsigned long delta)
{
- const struct pe_base_relocs *base_relocs;
-
- for ( base_relocs = __base_relocs_start; base_relocs < __base_relocs_end; )
- {
- unsigned int i = 0, n;
-
- n = (base_relocs->size - sizeof(*base_relocs)) /
- sizeof(*base_relocs->entries);
-
- /*
- * Relevant l{2,3}_bootmap entries get initialized explicitly in
- * efi_arch_memory_setup(), so we must not apply relocations there.
- * l2_directmap's first slot, otoh, should be handled normally, as
- * efi_arch_memory_setup() won't touch it (xen_phys_start should
- * never be zero).
- */
- if ( xen_phys_start + base_relocs->rva == (unsigned long)l3_bootmap ||
- xen_phys_start + base_relocs->rva == (unsigned long)l2_bootmap )
- i = n;
-
- for ( ; i < n; ++i )
- {
- unsigned long addr = xen_phys_start + base_relocs->rva +
- (base_relocs->entries[i] & 0xfff);
-
- switch ( base_relocs->entries[i] >> 12 )
- {
- case PE_BASE_RELOC_ABS:
- break;
- case PE_BASE_RELOC_HIGHLOW:
- if ( delta )
- {
- *(u32 *)addr += delta;
- if ( in_page_tables(addr) )
- *(u32 *)addr += xen_phys_start;
- }
- break;
- case PE_BASE_RELOC_DIR64:
- if ( delta )
- {
- *(u64 *)addr += delta;
- if ( in_page_tables(addr) )
- *(u64 *)addr += xen_phys_start;
- }
- break;
- default:
- blexit(L"Unsupported relocation type");
- }
- }
- base_relocs = (const void *)(base_relocs->entries + i + (i & 1));
- }
+ if (!reloc_pe_back(delta, xen_phys_start, __base_relocs_start,
__base_relocs_end))
+ blexit(L"Unsupported relocation type");
}
extern const s32 __trampoline_rel_start[], __trampoline_rel_stop[];
--
2.45.2
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |