Hello. On 64-bit systems the code may be loaded above 4GiB. When grub tries
to switch to 32-bit mode before launching linux it causes the reboot. Here
is a patch to make this part of code into a trampoline
--
Regards
Vladimir 'phcoder' Serbinenko
diff --git a/ChangeLog b/ChangeLog
index c307abe..6bc043a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2009-05-09 Vladimir Serbinenko <phco...@gmail.com>
+
+ trampoline for linux on 64-bit platform
+
+ * conf/x86_64-efi.rmk (linux_mod_SOURCES): added
+ loader/i386/efi/linux_trampoline.S
+ * include/grub/x86_64/efi/loader.h (grub_linux_real_boot): removed
+ declration
+ * kern/x86_64/efi/startup.S (grub_linux_real_boot): moved from here
+ * loader/i386/efi/linux_trampoline.S: moved here
+ * loader/i386/efi/linux.c (allocate_pages): reserve space for trampoline
+ (jumpvector): removed
+ (grub_linux_trampoline_start): new declaration
+ (grub_linux_trampoline_end): likewise
+ (grub_linux_boot): use trampoline when on 64-bit platform
+ * loader/i386/linux.c: likewise
+
2009-05-08 Robert Millan <rmh.g...@aybabtu.com>
* util/i386/pc/grub-setup.c (setup): Factorize find_usable_region(),
diff --git a/conf/x86_64-efi.rmk b/conf/x86_64-efi.rmk
index 92ad9f7..45e8527 100644
--- a/conf/x86_64-efi.rmk
+++ b/conf/x86_64-efi.rmk
@@ -137,7 +137,7 @@ appleldr_mod_CFLAGS = $(COMMON_CFLAGS)
appleldr_mod_LDFLAGS = $(COMMON_LDFLAGS)
# For linux.mod.
-linux_mod_SOURCES = loader/i386/efi/linux.c
+linux_mod_SOURCES = loader/i386/efi/linux.c loader/i386/efi/linux_trampoline.S
linux_mod_CFLAGS = $(COMMON_CFLAGS)
linux_mod_LDFLAGS = $(COMMON_LDFLAGS)
diff --git a/include/grub/x86_64/efi/loader.h b/include/grub/x86_64/efi/loader.h
index fac6746..7c302e8 100644
--- a/include/grub/x86_64/efi/loader.h
+++ b/include/grub/x86_64/efi/loader.h
@@ -22,6 +22,5 @@
#include <grub/types.h>
#include <grub/symbol.h>
-void EXPORT_FUNC(grub_linux_real_boot) (void);
#endif /* ! GRUB_LOADER_MACHINE_HEADER */
diff --git a/kern/x86_64/efi/startup.S b/kern/x86_64/efi/startup.S
index 2cb1fd4..fb4fc7b 100644
--- a/kern/x86_64/efi/startup.S
+++ b/kern/x86_64/efi/startup.S
@@ -61,26 +61,3 @@ codestart:
call EXT_C(grub_main)
ret
- .code32
-
-FUNCTION(grub_linux_real_boot)
- /* Turn off PG bit in CR0 and set CR3 to zero. */
- movl %cr0, %eax
- andl $0x7FFFFFFF, %eax
- movl %eax, %cr0
-
- /* Setup EFER (Extended Feature Enable Register). */
- movl $0xc0000080, %ecx
- rdmsr
-
- /* Disable Long Mode. */
- andl $0xFFFFFEFF, %eax
-
- /* Make changes effective. */
- wrmsr
-
- /* Disable PAE. */
- xorl %eax, %eax
- movl %eax, %cr4
-
- jmp *%ebx
diff --git a/loader/i386/efi/linux.c b/loader/i386/efi/linux.c
index 9be88aa..09b8d82 100644
--- a/loader/i386/efi/linux.c
+++ b/loader/i386/efi/linux.c
@@ -241,7 +241,7 @@ allocate_pages (grub_size_t prot_size)
/* Next, find free pages for the protected mode code. */
/* XXX what happens if anything is using this address? */
- prot_mode_mem = grub_efi_allocate_pages (0x100000, prot_mode_pages);
+ prot_mode_mem = grub_efi_allocate_pages (0x100000, prot_mode_pages + 1);
if (! prot_mode_mem)
{
grub_error (GRUB_ERR_OUT_OF_MEMORY,
@@ -286,11 +286,8 @@ grub_e820_add_region (struct grub_e820_mmap *e820_map, int *e820_num,
}
#ifdef __x86_64__
-struct
-{
- grub_uint32_t kernel_entry;
- grub_uint32_t kernel_cs;
-} jumpvector;
+extern grub_uint8_t grub_linux_trampoline_start[];
+extern grub_uint8_t grub_linux_trampoline_end[];
#endif
static grub_err_t
@@ -384,6 +381,8 @@ grub_linux_boot (void)
params->v0204.efi_mmap_size = mmap_size;
}
+#else
+
/* Hardware interrupts are not safe any longer. */
asm volatile ("cli" : : );
@@ -391,18 +390,6 @@ grub_linux_boot (void)
asm volatile ("lidt %0" : : "m" (idt_desc));
asm volatile ("lgdt %0" : : "m" (gdt_desc));
-#ifdef __x86_64__
-
- jumpvector.kernel_entry = (grub_uint64_t) grub_linux_real_boot;
- jumpvector.kernel_cs = 0x10;
-
- asm volatile ( "mov %0, %%rbx" : : "m" (params->code32_start));
- asm volatile ( "mov %0, %%rsi" : : "m" (real_mode_mem));
-
- asm volatile ( "ljmp *%0" : : "m" (jumpvector));
-
-#else
-
/* Pass parameters. */
asm volatile ("movl %0, %%ecx" : : "m" (params->code32_start));
asm volatile ("movl %0, %%esi" : : "m" (real_mode_mem));
diff --git a/loader/i386/efi/linux_trampoline.S b/loader/i386/efi/linux_trampoline.S
new file mode 100644
index 0000000..39821e1
--- /dev/null
+++ b/loader/i386/efi/linux_trampoline.S
@@ -0,0 +1,112 @@
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2009 Free Software Foundation, Inc.
+ *
+ * GRUB is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GRUB is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/symbol.h>
+
+
+ .p2align 4 /* force 16-byte alignment */
+VARIABLE(grub_linux_trampoline_start)
+ cli
+ /* %rdi contains protected memory start and %rsi
+ contains real memory start. */
+
+ mov %rsi, %rbx
+
+ call base
+base:
+ pop %rsi
+
+ lea (cont1-base)(%rsi, 1), %rax
+ mov %eax, (jump_vector-base)(%rsi,1)
+
+ lea (gdt-base)(%rsi, 1), %rax
+ mov %rax, (gdtaddr-base)(%rsi,1)
+
+ /* Switch to compatibility mode. */
+
+ lidt (idtdesc-base)(%rsi,1)
+ lgdt (gdtdesc-base)(%rsi,1)
+
+ /* Update %cs. Thanks to David Miller for pointing this mistake out. */
+ ljmp *(jump_vector-base)(%rsi,1)
+cont1:
+ .code32
+
+ /* Update other registers. */
+ mov $0x18, %eax
+ mov %eax, %ds
+ mov %eax, %es
+ mov %eax, %fs
+ mov %eax, %gs
+ mov %eax, %ss
+
+ /* Disable paging. */
+ mov %cr0, %eax
+ and $0x7fffffff, %eax
+ mov %eax, %cr0
+
+ /* Disable amd64. */
+ mov $0xc0000080, %ecx
+ rdmsr
+ and $0xfffffeff, %eax
+ wrmsr
+
+ /* Turn off PAE. */
+ movl %cr4, %eax
+ and $0xffffffcf, %eax
+ mov %eax, %cr4
+
+ jmp cont2
+cont2:
+ .code32
+
+ mov %ebx, %esi
+
+ jmp *%edi
+
+ /* GDT. */
+ .p2align 4
+gdt:
+ /* NULL. */
+ .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+
+ /* Reserved. */
+ .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+
+ /* Code segment. */
+ .byte 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x9A, 0xCF, 0x00
+
+ /* Data segment. */
+ .byte 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x92, 0xCF, 0x00
+
+gdtdesc:
+ .word 31
+gdtaddr:
+ .quad gdt
+
+idtdesc:
+ .word 0
+idtaddr:
+ .quad 0
+
+ .p2align 4
+jump_vector:
+ /* Jump location. Is filled by the code */
+ .long 0
+ .long 0x10
+VARIABLE(grub_linux_trampoline_end)
diff --git a/loader/i386/linux.c b/loader/i386/linux.c
index d67a5f8..07fdb99 100644
--- a/loader/i386/linux.c
+++ b/loader/i386/linux.c
@@ -432,11 +432,8 @@ grub_linux_setup_video (struct linux_kernel_params *params)
}
#ifdef __x86_64__
-struct
-{
- grub_uint32_t kernel_entry;
- grub_uint32_t kernel_cs;
-} jumpvector;
+extern grub_uint8_t grub_linux_trampoline_start[];
+extern grub_uint8_t grub_linux_trampoline_end[];
#endif
static grub_err_t
@@ -548,6 +545,16 @@ grub_linux_boot (void)
grub_mmap_iterate (hook);
params->mmap_size = e820_num;
+#ifdef __x86_64__
+
+ grub_memcpy ((char *) prot_mode_mem + (prot_mode_pages << 12),
+ grub_linux_trampoline_start,
+ grub_linux_trampoline_end - grub_linux_trampoline_start);
+
+ ((void (*) (void *, unsigned long)) ((char *) prot_mode_mem
+ + (prot_mode_pages << 12)))
+ (params->code32_start, real_mode_mem);
+#else
/* Hardware interrupts are not safe any longer. */
asm volatile ("cli" : : );
@@ -556,18 +563,6 @@ grub_linux_boot (void)
asm volatile ("lidt %0" : : "m" (idt_desc));
asm volatile ("lgdt %0" : : "m" (gdt_desc));
-#ifdef __x86_64__
-
- jumpvector.kernel_entry = (grub_uint64_t) grub_linux_real_boot;
- jumpvector.kernel_cs = 0x10;
-
- asm volatile ( "mov %0, %%rbx" : : "m" (params->code32_start));
- asm volatile ( "mov %0, %%rsi" : : "m" (real_mode_mem));
-
- asm volatile ( "ljmp *%0" : : "m" (jumpvector));
-
-#else
-
/* Pass parameters. */
asm volatile ("movl %0, %%ecx" : : "m" (params->code32_start));
asm volatile ("movl %0, %%esi" : : "m" (real_mode_mem));
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