[PATCH v7 3/7] kexec, x86: Fix bzImage real-mode booting
Yinghai Lu
yinghai at kernel.org
Thu Jan 24 15:44:20 EST 2013
We need to keep space for bss, heap/stack before command line.
otherwise command_line will be cleared by kernel 16bit init code.
also need to set 32bit start in real_mode header, kernel 16bit code
need to jump there.
Also don't touch regs16 if --real-mode is not specified.
Signed-off-by: Yinghai Lu <yinghai at kernel.org>
---
kexec/arch/i386/kexec-bzImage.c | 63 +++++++++++++++++++++++++++++++--------
1 file changed, 50 insertions(+), 13 deletions(-)
diff --git a/kexec/arch/i386/kexec-bzImage.c b/kexec/arch/i386/kexec-bzImage.c
index 4cc394d..1a33d47 100644
--- a/kexec/arch/i386/kexec-bzImage.c
+++ b/kexec/arch/i386/kexec-bzImage.c
@@ -130,6 +130,8 @@ int do_bzImage_load(struct kexec_info *info,
unsigned long kernel32_load_addr;
char *modified_cmdline;
unsigned long cmdline_end;
+ unsigned long kern16_size_needed;
+ unsigned long heap_size = 0;
/*
* Find out about the file I am about to load.
@@ -221,9 +223,31 @@ int do_bzImage_load(struct kexec_info *info,
elf_rel_build_load(info, &info->rhdr, purgatory, purgatory_size,
0x3000, 640*1024, -1, 0);
dbgprintf("Loaded purgatory at addr 0x%lx\n", info->rhdr.rel_addr);
+
/* The argument/parameter segment */
- setup_size = kern16_size + command_line_len + PURGATORY_CMDLINE_SIZE;
+ if (real_mode_entry) {
+ /* need to include size for bss and heap etc */
+ if (setup_header.protocol_version >= 0x0201)
+ kern16_size_needed = setup_header.heap_end_ptr;
+ else
+ kern16_size_needed = kern16_size + 8192; /* bss */
+ if (kern16_size_needed < kern16_size)
+ kern16_size_needed = kern16_size;
+ if (kern16_size_needed > 0xfffc)
+ die("kern16_size_needed is more then 64k\n");
+ heap_size = 0xfffc - kern16_size_needed; /* less 64k */
+ heap_size &= ~(0x200 - 1);
+ kern16_size_needed += heap_size;
+ } else {
+ kern16_size_needed = kern16_size;
+ /* need to bigger than size of struct bootparams */
+ if (kern16_size_needed < 4096)
+ kern16_size_needed = 4096;
+ }
+ setup_size = kern16_size_needed + command_line_len +
+ PURGATORY_CMDLINE_SIZE;
real_mode = xmalloc(setup_size);
+ memset(real_mode, 0, setup_size);
memcpy(real_mode, kernel, kern16_size);
if (!real_mode_entry)
clean_boot_params((unsigned char *)real_mode, kern16_size);
@@ -279,11 +303,18 @@ int do_bzImage_load(struct kexec_info *info,
/* Tell the kernel what is going on */
setup_linux_bootloader_parameters(info, real_mode, setup_base,
- kern16_size, command_line, command_line_len,
+ kern16_size_needed, command_line, command_line_len,
initrd, initrd_len);
+ if (real_mode_entry && real_mode->protocol_version >= 0x0201) {
+ real_mode->loader_flags |= 0x80; /* CAN_USE_HEAP */
+ real_mode->heap_end_ptr += heap_size - 0x200; /*stack*/
+ }
+
/* Get the initial register values */
- elf_rel_get_symbol(&info->rhdr, "entry16_regs", ®s16, sizeof(regs16));
+ if (real_mode_entry)
+ elf_rel_get_symbol(&info->rhdr, "entry16_regs",
+ ®s16, sizeof(regs16));
elf_rel_get_symbol(&info->rhdr, "entry32_regs", ®s32, sizeof(regs32));
/*
@@ -302,16 +333,18 @@ int do_bzImage_load(struct kexec_info *info,
/*
* Initialize the 16bit start information.
*/
- regs16.ds = regs16.es = regs16.fs = regs16.gs = setup_base >> 4;
- regs16.cs = regs16.ds + 0x20;
- regs16.ip = 0;
- /* XXX: Documentation/i386/boot.txt says 'ss' must equal 'ds' */
- regs16.ss = (elf_rel_get_addr(&info->rhdr, "stack_end") - 64*1024) >> 4;
- /* XXX: Documentation/i386/boot.txt says 'sp' must equal heap_end */
- regs16.esp = 0xFFFC;
if (real_mode_entry) {
+ regs16.ds = regs16.es = regs16.fs = regs16.gs = setup_base >> 4;
+ regs16.cs = regs16.ds + 0x20;
+ regs16.ip = 0;
+ /* XXX: Documentation/i386/boot.txt says 'ss' must equal 'ds' */
+ regs16.ss = (elf_rel_get_addr(&info->rhdr, "stack_end") - 64*1024) >> 4;
+ /* XXX: Documentation/i386/boot.txt says 'sp' must equal heap_end */
+ regs16.esp = 0xFFFC;
+
printf("Starting the kernel in real mode\n");
regs32.eip = elf_rel_get_addr(&info->rhdr, "entry16");
+ real_mode->kernel_start = kernel32_load_addr;
}
if (real_mode_entry && kexec_debug) {
unsigned long entry16_debug, pre32, first32;
@@ -331,10 +364,14 @@ int do_bzImage_load(struct kexec_info *info,
regs32.eip = entry16_debug;
}
- elf_rel_set_symbol(&info->rhdr, "entry16_regs", ®s16, sizeof(regs16));
- elf_rel_set_symbol(&info->rhdr, "entry16_debug_regs", ®s16, sizeof(regs16));
+ if (real_mode_entry) {
+ elf_rel_set_symbol(&info->rhdr, "entry16_regs",
+ ®s16, sizeof(regs16));
+ elf_rel_set_symbol(&info->rhdr, "entry16_debug_regs",
+ ®s16, sizeof(regs16));
+ }
elf_rel_set_symbol(&info->rhdr, "entry32_regs", ®s32, sizeof(regs32));
- cmdline_end = setup_base + kern16_size + command_line_len - 1;
+ cmdline_end = setup_base + kern16_size_needed + command_line_len - 1;
elf_rel_set_symbol(&info->rhdr, "cmdline_end", &cmdline_end,
sizeof(unsigned long));
--
1.7.10.4
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