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powerpc: Kexec exit should not use magic numbers

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Commit 54622f10a6 ("powerpc: Support for
relocatable kdump kernel") added a magic flag value in a register to
tell purgatory that it should be a panic kernel.  This part is wrong
and is reverted by this commit.

The kernel gets a list of memory blocks and a entry point from user space.
Its job is to copy the blocks into place and then branch to the designated
entry point (after turning "off" the mmu).

The user space tool inserts a trampoline, called purgatory, that runs
before the user supplied code.   Its job is to establish the entry
environment for the new kernel or other application based on the contents
of memory.  The purgatory code is compiled and embedded in the tool,
where it is later patched using the elf symbol table using elf symbols.

Since the tool knows it is creating a purgatory that will run after a
kernel crash, it should just patch purgatory (or the kernel directly)
if something needs to happen.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Milton Miller
2008-10-22 10:39:18 +00:00
committed by Paul Mackerras
parent 8694a1c605
commit 1767c8f392
3 changed files with 5 additions and 19 deletions
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9
arch/powerpc/kernel/machine_kexec_64.c
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@@ -255,14 +255,11 @@ static union thread_union kexec_stack
/* Our assembly helper, in kexec_stub.S */
extern NORET_TYPE void kexec_sequence(void *newstack, unsigned long start,
void *image, void *control,
void (*clear_all)(void),
unsigned long kdump_flag) ATTRIB_NORET;
void (*clear_all)(void)) ATTRIB_NORET;
/* too late to fail here */
void default_machine_kexec(struct kimage *image)
{
unsigned long kdump_flag = 0;
/* prepare control code if any */
/*
@@ -275,8 +272,6 @@ void default_machine_kexec(struct kimage *image)
if (crashing_cpu == -1)
kexec_prepare_cpus();
else
kdump_flag = KDUMP_SIGNATURE;
/* switch to a staticly allocated stack. Based on irq stack code.
* XXX: the task struct will likely be invalid once we do the copy!
@@ -289,7 +284,7 @@ void default_machine_kexec(struct kimage *image)
*/
kexec_sequence(&kexec_stack, image->start, image,
page_address(image->control_code_page),
ppc_md.hpte_clear_all, kdump_flag);
ppc_md.hpte_clear_all);
/* NOTREACHED */
}