[PATCH] lguest: use standard bootloader format, fix badly-sizedinitrds
From: Rusty Russell
Date: Sun May 06 2007 - 21:22:16 EST
Eric Biederman complained that lguest doesn't use the Linux standard
boot header format. He's got a good point.
This also simplifies the code: the example launcher writes the header
directly, rather than lguest writing into it during boot.
While we're touching this code, we also fix the problem of initrd's
which don't have a page-aligned size.
This anticipates changing the paravirt-finding routines to use a
"platform type" field from %esi, rather than a "probe all until one
succeeds" routine, but doesn't actually change that code.
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
Documentation/lguest/lguest.c | 50 ++++++++++++++++++++++++---------------
drivers/lguest/lguest.c | 22 +++++++----------
drivers/lguest/lguest_asm.S | 5 +++
drivers/lguest/lguest_user.c | 4 ---
include/linux/lguest.h | 5 ---
include/linux/lguest_launcher.h | 8 ------
6 files changed, 46 insertions(+), 48 deletions(-)
===================================================================
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -30,10 +30,12 @@
#include <termios.h>
#include <getopt.h>
#include <zlib.h>
+typedef unsigned long long u64;
typedef uint32_t u32;
typedef uint16_t u16;
typedef uint8_t u8;
#include "../../include/linux/lguest_launcher.h"
+#include "../../include/asm-i386/e820.h"
#define PAGE_PRESENT 0x7 /* Present, RW, Execute */
#define NET_PEERNUM 1
@@ -241,31 +243,33 @@ static unsigned long load_kernel(int fd,
return load_bzimage(fd, page_offset);
}
+static inline unsigned long page_align(unsigned long addr)
+{
+ return ((addr + getpagesize()-1) & ~(getpagesize()-1));
+}
+
/* initrd gets loaded at top of memory: return length. */
static unsigned long load_initrd(const char *name, unsigned long mem)
{
int ifd;
struct stat st;
+ unsigned long len;
void *iaddr;
ifd = open_or_die(name, O_RDONLY);
if (fstat(ifd, &st) < 0)
err(1, "fstat() on initrd '%s'", name);
- iaddr = mmap((void *)mem - st.st_size, st.st_size,
+ len = page_align(st.st_size);
+ iaddr = mmap((void *)mem - len, st.st_size,
PROT_READ|PROT_EXEC|PROT_WRITE,
MAP_FIXED|MAP_PRIVATE, ifd, 0);
- if (iaddr != (void *)mem - st.st_size)
+ if (iaddr != (void *)mem - len)
err(1, "Mmaping initrd '%s' returned %p not %p",
- name, iaddr, (void *)mem - st.st_size);
+ name, iaddr, (void *)mem - len);
close(ifd);
verbose("mapped initrd %s size=%lu @ %p\n", name, st.st_size, iaddr);
- return st.st_size;
-}
-
-static inline unsigned long page_align(unsigned long addr)
-{
- return ((addr + getpagesize()-1) & ~(getpagesize()-1));
+ return len;
}
static unsigned long setup_pagetables(unsigned long mem,
@@ -933,10 +937,10 @@ static void usage(void)
int main(int argc, char *argv[])
{
- unsigned long mem, pgdir, start, page_offset;
+ unsigned long mem, pgdir, start, page_offset, initrd_size = 0;
int c, lguest_fd, waker_fd;
struct device_list device_list;
- struct lguest_boot_info *boot = (void *)0;
+ void *boot = (void *)0;
const char *initrd_name = NULL;
device_list.max_infd = -1;
@@ -984,15 +988,25 @@ int main(int argc, char *argv[])
map_device_descriptors(&device_list, mem);
/* Map the initrd image if requested */
- if (initrd_name)
- boot->initrd_size = load_initrd(initrd_name, mem);
+ if (initrd_name) {
+ initrd_size = load_initrd(initrd_name, mem);
+ *(unsigned long *)(boot+0x218) = mem - initrd_size;
+ *(unsigned long *)(boot+0x21c) = initrd_size;
+ *(unsigned char *)(boot+0x210) = 0xFF;
+ }
/* Set up the initial linar pagetables. */
- pgdir = setup_pagetables(mem, boot->initrd_size, page_offset);
-
- /* Give the guest the boot information it needs. */
- concat(boot->cmdline, argv+optind+2);
- boot->max_pfn = mem/getpagesize();
+ pgdir = setup_pagetables(mem, initrd_size, page_offset);
+
+ /* E820 memory map: ours is a simple, single region. */
+ *(char*)(boot+E820NR) = 1;
+ *((struct e820entry *)(boot+E820MAP))
+ = ((struct e820entry) { 0, mem, E820_RAM });
+ /* Command line pointer and command line (at 4096) */
+ *(void **)(boot + 0x228) = boot + 4096;
+ concat(boot + 4096, argv+optind+2);
+ /* Paravirt type: 1 == lguest */
+ *(int *)(boot + 0x23c) = 1;
lguest_fd = tell_kernel(pgdir, start, page_offset);
waker_fd = setup_waker(&device_list);
===================================================================
--- a/drivers/lguest/lguest.c
+++ b/drivers/lguest/lguest.c
@@ -52,7 +52,6 @@ struct lguest_data lguest_data = {
.blocked_interrupts = { 1 }, /* Block timer interrupts */
};
struct lguest_device_desc *lguest_devices;
-static __initdata const struct lguest_boot_info *boot = __va(0);
static enum paravirt_lazy_mode lazy_mode;
static void lguest_lazy_mode(enum paravirt_lazy_mode mode)
@@ -377,8 +376,7 @@ static __init char *lguest_memory_setup(
/* We do this here because lockcheck barfs if before start_kernel */
atomic_notifier_chain_register(&panic_notifier_list, &paniced);
- e820.nr_map = 0;
- add_memory_region(0, PFN_PHYS(boot->max_pfn), E820_RAM);
+ add_memory_region(E820_MAP->addr, E820_MAP->size, E820_MAP->type);
return "LGUEST";
}
@@ -409,8 +407,14 @@ static unsigned lguest_patch(u8 type, u1
return insn_len;
}
-__init void lguest_init(void)
-{
+__init void lguest_init(void *boot)
+{
+ /* Copy boot parameters first. */
+ memcpy(boot_params, boot, PARAM_SIZE);
+ memcpy(boot_command_line,
+ __va(*(unsigned long *)(boot_params + NEW_CL_POINTER)),
+ COMMAND_LINE_SIZE);
+
paravirt_ops.name = "lguest";
paravirt_ops.paravirt_enabled = 1;
paravirt_ops.kernel_rpl = 1;
@@ -459,7 +463,6 @@ __init void lguest_init(void)
paravirt_ops.wbinvd = lguest_wbinvd;
hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
- strncpy(boot_command_line, boot->cmdline, COMMAND_LINE_SIZE);
/* We use top of mem for initial pagetables. */
init_pg_tables_end = __pa(pg0);
@@ -485,13 +488,6 @@ __init void lguest_init(void)
add_preferred_console("hvc", 0, NULL);
- if (boot->initrd_size) {
- /* We stash this at top of memory. */
- INITRD_START = boot->max_pfn*PAGE_SIZE - boot->initrd_size;
- INITRD_SIZE = boot->initrd_size;
- LOADER_TYPE = 0xFF;
- }
-
pm_power_off = lguest_power_off;
start_kernel();
}
===================================================================
--- a/drivers/lguest/lguest_asm.S
+++ b/drivers/lguest/lguest_asm.S
@@ -10,7 +10,8 @@
* This is where we begin: we have a magic signature which the launcher looks
* for. The plan is that the Linux boot protocol will be extended with a
* "platform type" field which will guide us here from the normal entry point,
- * but for the moment this suffices.
+ * but for the moment this suffices. We pass the virtual address of the boot
+ * info to lguest_init().
*
* We put it in .init.text will be discarded after boot.
*/
@@ -18,6 +19,8 @@
.ascii "GenuineLguest"
/* Set up initial stack. */
movl $(init_thread_union+THREAD_SIZE),%esp
+ movl %esi, %eax
+ addl $__PAGE_OFFSET, %eax
jmp lguest_init
/* The templates for inline patching. */
===================================================================
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -7,13 +7,11 @@ static void setup_regs(struct lguest_reg
static void setup_regs(struct lguest_regs *regs, unsigned long start)
{
/* Write out stack in format lguest expects, so we can switch to it. */
- regs->edi = LGUEST_MAGIC_EDI;
- regs->ebp = LGUEST_MAGIC_EBP;
- regs->esi = LGUEST_MAGIC_ESI;
regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
regs->cs = __KERNEL_CS|GUEST_PL;
regs->eflags = 0x202; /* Interrupts enabled. */
regs->eip = start;
+ /* esi points to our boot information (physical address 0) */
}
/* + addr */
===================================================================
--- a/include/linux/lguest.h
+++ b/include/linux/lguest.h
@@ -2,11 +2,6 @@
* this is subject to wild and random change between versions. */
#ifndef _ASM_LGUEST_H
#define _ASM_LGUEST_H
-
-/* These are randomly chosen numbers which indicate we're an lguest at boot */
-#define LGUEST_MAGIC_EBP 0x4C687970
-#define LGUEST_MAGIC_EDI 0x652D4D65
-#define LGUEST_MAGIC_ESI 0xFFFFFFFF
#ifndef __ASSEMBLY__
#include <asm/irq.h>
===================================================================
--- a/include/linux/lguest_launcher.h
+++ b/include/linux/lguest_launcher.h
@@ -15,14 +15,6 @@ struct lguest_dma
u32 used_len;
u32 addr[LGUEST_MAX_DMA_SECTIONS];
u16 len[LGUEST_MAX_DMA_SECTIONS];
-};
-
-/* This is found at address 0. */
-struct lguest_boot_info
-{
- u32 max_pfn;
- u32 initrd_size;
- char cmdline[256];
};
struct lguest_block_page
-
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