[PATCH 2/3] zImage: Cleanup and improve prep_kernel()
David Gibson
david at gibson.dropbear.id.au
Fri Feb 16 17:27:39 EST 2007
This patch rewrites prep_kernel() in the zImage wrapper code to be
clearer and more flexible. Notable changes:
- Handling of the initrd image from prep_kernel() has moved
into a new prep_initrd() function.
- The address of the initrd image is now added as device tree
properties, as the kernel expects.
- We only copy a packaged initrd image to a new location if it
is in danger of being clobbered when the kernel moves to its final
location, instead of always.
- By default we decompress the kernel directly to address 0,
instead of requiring it to relocate itself. Platforms (such as OF)
where doing this could clobber still-live firmware data structures can
override the vmlinux_alloc hook to provide an alternate place to
decompress the kernel.
- We no longer pass lots of information between functions in
global variables.
Signed-off-by: David Gibson <dwg at au1.ibm.com>
---
arch/powerpc/boot/main.c | 172 ++++++++++++++++++++++++++++-------------------
arch/powerpc/boot/of.c | 12 +++
arch/powerpc/boot/ops.h | 1
3 files changed, 117 insertions(+), 68 deletions(-)
Index: working-2.6/arch/powerpc/boot/main.c
===================================================================
--- working-2.6.orig/arch/powerpc/boot/main.c 2007-02-16 12:31:27.000000000 +1100
+++ working-2.6/arch/powerpc/boot/main.c 2007-02-16 12:31:47.000000000 +1100
@@ -31,24 +31,21 @@ extern char _dtb_start[];
extern char _dtb_end[];
struct addr_range {
- unsigned long addr;
+ void *addr;
unsigned long size;
- unsigned long memsize;
};
-static struct addr_range vmlinux;
-static struct addr_range vmlinuz;
-static struct addr_range initrd;
-
-static unsigned long elfoffset;
-static int is_64bit;
-static char elfheader[256];
+struct elf_info {
+ unsigned long loadsize;
+ unsigned long memsize;
+ unsigned long elfoffset;
+} vmlinux;
typedef void (*kernel_entry_t)(unsigned long, unsigned long, void *);
#undef DEBUG
-static int is_elf64(void *hdr)
+static int parse_elf64(void *hdr, struct elf_info *info)
{
Elf64_Ehdr *elf64 = hdr;
Elf64_Phdr *elf64ph;
@@ -72,15 +69,14 @@ static int is_elf64(void *hdr)
if (i >= (unsigned int)elf64->e_phnum)
return 0;
- elfoffset = (unsigned long)elf64ph->p_offset;
- vmlinux.size = (unsigned long)elf64ph->p_filesz;
- vmlinux.memsize = (unsigned long)elf64ph->p_memsz;
+ info->loadsize = (unsigned long)elf64ph->p_filesz;
+ info->memsize = (unsigned long)elf64ph->p_memsz;
+ info->elfoffset = (unsigned long)elf64ph->p_offset;
- is_64bit = 1;
return 1;
}
-static int is_elf32(void *hdr)
+static int parse_elf32(void *hdr, struct elf_info *info)
{
Elf32_Ehdr *elf32 = hdr;
Elf32_Phdr *elf32ph;
@@ -96,7 +92,6 @@ static int is_elf32(void *hdr)
elf32->e_machine == EM_PPC))
return 0;
- elf32 = (Elf32_Ehdr *)elfheader;
elf32ph = (Elf32_Phdr *) ((unsigned long)elf32 + elf32->e_phoff);
for (i = 0; i < elf32->e_phnum; i++, elf32ph++)
if (elf32ph->p_type == PT_LOAD)
@@ -104,25 +99,28 @@ static int is_elf32(void *hdr)
if (i >= elf32->e_phnum)
return 0;
- elfoffset = elf32ph->p_offset;
- vmlinux.size = elf32ph->p_filesz;
- vmlinux.memsize = elf32ph->p_memsz;
+ info->loadsize = elf32ph->p_filesz;
+ info->memsize = elf32ph->p_memsz;
+ info->elfoffset = elf32ph->p_offset;
return 1;
}
-static void prep_kernel(unsigned long a1, unsigned long a2)
+static struct addr_range prep_kernel(void)
{
static struct gunzip_state gzstate;
- int len;
+ static char elfheader[256];
- vmlinuz.addr = (unsigned long)_vmlinux_start;
- vmlinuz.size = (unsigned long)(_vmlinux_end - _vmlinux_start);
+ void *vmlinuz_addr = _vmlinux_start;
+ unsigned long vmlinuz_size = _vmlinux_end - _vmlinux_start;
+ void *addr = 0;
+ struct elf_info ei;
+ int len;
/* gunzip the ELF header of the kernel */
- gunzip_start(&gzstate, (void *)vmlinuz.addr, vmlinuz.size);
+ gunzip_start(&gzstate, vmlinuz_addr, vmlinuz_size);
gunzip_exactly(&gzstate, elfheader, sizeof(elfheader));
- if (!is_elf64(elfheader) && !is_elf32(elfheader)) {
+ if (!parse_elf64(elfheader, &ei) && !parse_elf32(elfheader, &ei)) {
printf("Error: not a valid PPC32 or PPC64 ELF file!\n\r");
exit();
}
@@ -134,55 +132,92 @@ static void prep_kernel(unsigned long a1
* the kernel bss must be claimed (it will be zero'd by the
* kernel itself)
*/
- printf("Allocating 0x%lx bytes for kernel ...\n\r", vmlinux.memsize);
- vmlinux.addr = (unsigned long)malloc(vmlinux.memsize);
- if (vmlinux.addr == 0) {
- printf("Can't allocate memory for kernel image !\n\r");
- exit();
+ printf("Allocating 0x%lx bytes for kernel ...\n\r", ei.memsize);
+
+ if (platform_ops.vmlinux_alloc) {
+ addr = platform_ops.vmlinux_alloc(ei.memsize);
+ } else {
+ if ((unsigned long)_start < ei.memsize) {
+ printf("Insufficient memory for kernel at address 0!"
+ " (_start=%lx)\n\r", _start);
+ exit();
+ }
}
+ /* Finally, gunzip the kernel */
+ printf("gunzipping (0x%p <- 0x%p:0x%p)...", addr,
+ vmlinuz_addr, vmlinuz_addr+vmlinuz_size);
+ /* discard up to the actual load data */
+ gunzip_discard(&gzstate, ei.elfoffset - sizeof(elfheader));
+ len = gunzip_finish(&gzstate, addr, ei.memsize);
+ printf("done 0x%lx bytes\n\r", len);
+
+ flush_cache(addr, ei.loadsize);
+
+ return (struct addr_range){addr, ei.memsize};
+}
+
+static struct addr_range prep_initrd(struct addr_range vmlinux,
+ unsigned long initrd_addr,
+ unsigned long initrd_size)
+{
+ void *devp;
+ u32 initrd_start, initrd_end;
+
+ /* If we have an image attached to us, it overrides anything
+ * supplied by the loader. */
+ if (_initrd_end > _initrd_start) {
+ printf("Attached initrd image at 0x%p-0x%p\n\r",
+ _initrd_start, _initrd_end);
+ initrd_addr = (unsigned long)_initrd_start;
+ initrd_size = _initrd_end - _initrd_start;
+ } else if (initrd_size > 0) {
+ printf("Using loader supplied ramdisk at 0x%lx-0x%lx\n\r",
+ initrd_addr, initrd_addr + initrd_size);
+ }
+
+ /* If there's no initrd at all, we're done */
+ if (! initrd_size)
+ return (struct addr_range){0, 0};
+
/*
- * Now find the initrd
- *
- * First see if we have an image attached to us. If so
- * allocate memory for it and copy it there.
+ * If the initrd is too low it will be clobbered when the
+ * kernel relocates to its final location. In this case,
+ * allocate a safer place and move it.
*/
- initrd.size = (unsigned long)(_initrd_end - _initrd_start);
- initrd.memsize = initrd.size;
- if (initrd.size > 0) {
+ if (initrd_addr < vmlinux.size) {
+ void *old_addr = (void *)initrd_addr;
+
printf("Allocating 0x%lx bytes for initrd ...\n\r",
- initrd.size);
- initrd.addr = (unsigned long)malloc((u32)initrd.size);
- if (initrd.addr == 0) {
+ initrd_size);
+ initrd_addr = (unsigned long)malloc(initrd_size);
+ if (! initrd_addr) {
printf("Can't allocate memory for initial "
- "ramdisk !\n\r");
+ "ramdisk !\n\r");
exit();
}
- printf("initial ramdisk moving 0x%lx <- 0x%lx "
- "(0x%lx bytes)\n\r", initrd.addr,
- (unsigned long)_initrd_start, initrd.size);
- memmove((void *)initrd.addr, (void *)_initrd_start,
- initrd.size);
- printf("initrd head: 0x%lx\n\r",
- *((unsigned long *)initrd.addr));
- } else if (a2 != 0) {
- /* Otherwise, see if yaboot or another loader gave us an initrd */
- initrd.addr = a1;
- initrd.memsize = initrd.size = a2;
- printf("Using loader supplied initrd at 0x%lx (0x%lx bytes)\n\r",
- initrd.addr, initrd.size);
- }
-
- /* Eventually gunzip the kernel */
- printf("gunzipping (0x%lx <- 0x%lx:0x%0lx)...",
- vmlinux.addr, vmlinuz.addr, vmlinuz.addr+vmlinuz.size);
- /* discard up to the actual load data */
- gunzip_discard(&gzstate, elfoffset - sizeof(elfheader));
- len = gunzip_finish(&gzstate, (void *)vmlinux.addr,
- vmlinux.memsize);
- printf("done 0x%lx bytes\n\r", len);
+ printf("Relocating initrd 0x%p <- 0x%p (0x%lx bytes)\n\r",
+ initrd_addr, old_addr, initrd_size);
+ memmove((void *)initrd_addr, old_addr, initrd_size);
+ }
+
+ printf("initrd head: 0x%lx\n\r", *((unsigned long *)initrd_addr));
+
+ /* Tell the kernel initrd address via device tree */
+ devp = finddevice("/chosen");
+ if (! devp) {
+ printf("Device tree has no chosen node!\n\r");
+ exit();
+ }
+
+ initrd_start = (u32)initrd_addr;
+ initrd_end = (u32)initrd_addr + initrd_size;
+
+ setprop(devp, "linux,initrd-start", &initrd_start,
+ sizeof(initrd_start));
+ setprop(devp, "linux,initrd-end", &initrd_end, sizeof(initrd_end));
- flush_cache((void *)vmlinux.addr, vmlinux.size);
+ return (struct addr_range){(void *)initrd_addr, initrd_size};
}
/* A buffer that may be edited by tools operating on a zImage binary so as to
@@ -222,6 +257,7 @@ struct console_ops console_ops;
void start(unsigned long a1, unsigned long a2, void *promptr, void *sp)
{
+ struct addr_range vmlinux, initrd;
kernel_entry_t kentry;
char cmdline[COMMAND_LINE_SIZE];
unsigned long ft_addr = 0;
@@ -241,7 +277,8 @@ void start(unsigned long a1, unsigned lo
printf("\n\rzImage starting: loaded at 0x%p (sp: 0x%p)\n\r",
_start, sp);
- prep_kernel(a1, a2);
+ vmlinux = prep_kernel();
+ initrd = prep_initrd(vmlinux, a1, a2);
/* If cmdline came from zimage wrapper or if we can edit the one
* in the dt, print it out and edit it, if possible.
@@ -270,8 +307,7 @@ void start(unsigned long a1, unsigned lo
if (ft_addr)
kentry(ft_addr, 0, NULL);
else
- /* XXX initrd addr/size should be passed in properties */
- kentry(initrd.addr, initrd.size, promptr);
+ kentry((unsigned long)initrd.addr, initrd.size, promptr);
/* console closed so printf below may not work */
printf("Error: Linux kernel returned to zImage boot wrapper!\n\r");
Index: working-2.6/arch/powerpc/boot/ops.h
===================================================================
--- working-2.6.orig/arch/powerpc/boot/ops.h 2007-02-16 12:31:27.000000000 +1100
+++ working-2.6/arch/powerpc/boot/ops.h 2007-02-16 12:31:29.000000000 +1100
@@ -25,6 +25,7 @@ struct platform_ops {
void (*free)(void *ptr);
void * (*realloc)(void *ptr, unsigned long size);
void (*exit)(void);
+ void * (*vmlinux_alloc)(unsigned long size);
};
extern struct platform_ops platform_ops;
Index: working-2.6/arch/powerpc/boot/of.c
===================================================================
--- working-2.6.orig/arch/powerpc/boot/of.c 2007-02-16 12:31:27.000000000 +1100
+++ working-2.6/arch/powerpc/boot/of.c 2007-02-16 12:31:29.000000000 +1100
@@ -208,6 +208,17 @@ static void of_image_hdr(const void *hdr
}
}
+static void *of_vmlinux_alloc(unsigned long size)
+{
+ void *p = malloc(size);
+
+ if (!p) {
+ printf("Can't allocate memory for kernel image!\n\r");
+ exit();
+ }
+ return p;
+}
+
static void of_exit(void)
{
call_prom("exit", 0, 0);
@@ -261,6 +272,7 @@ int platform_init(void *promptr, char *d
platform_ops.image_hdr = of_image_hdr;
platform_ops.malloc = of_try_claim;
platform_ops.exit = of_exit;
+ platform_ops.vmlinux_alloc = of_vmlinux_alloc;
dt_ops.finddevice = of_finddevice;
dt_ops.getprop = of_getprop;
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