powerpc: Kexec exit should not use magic numbers

Commit 54622f10a6aabb8bb2bdacf3dd070046f03dc246 ("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>

1 files changed, 3 insertions, 6 deletions

diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index a243fd072a77..3053fe5c62f2 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -611,12 +611,10 @@ real_mode:	/* assume normal blr return */
 
 
 /*
- * kexec_sequence(newstack, start, image, control, clear_all(), kdump_flag)
+ * kexec_sequence(newstack, start, image, control, clear_all())
  *
  * does the grungy work with stack switching and real mode switches
  * also does simple calls to other code
- *
- * kdump_flag says whether the next kernel should be a kdump kernel.
  */
 
 _GLOBAL(kexec_sequence)
@@ -649,7 +647,7 @@ _GLOBAL(kexec_sequence)
         mr      r29,r5                  /* image (virt) */
         mr      r28,r6                  /* control, unused */
         mr      r27,r7                  /* clear_all() fn desc */
-        mr      r26,r8                  /* kdump flag */
+        mr      r26,r8                  /* spare */
         lhz     r25,PACAHWCPUID(r13)    /* get our phys cpu from paca */
 
         /* disable interrupts, we are overwriting kernel data next */
@@ -711,6 +709,5 @@ _GLOBAL(kexec_sequence)
         mr      r4,r30  # start, aka phys mem offset
         mtlr    4
         li      r5,0
-        mr      r6,r26                  /* kdump_flag */
-        blr     /* image->start(physid, image->start, 0, kdump_flag); */
+        blr     /* image->start(physid, image->start, 0); */
 #endif /* CONFIG_KEXEC */