sh: add kexec jump support
Add kexec jump support to the SuperH architecture.
Similar to the x86 implementation, with the following
exceptions:
- Instead of separating the assembly code flow into
two parts for regular kexec and kexec jump we use a
single code path. In the assembly snippet regular
kexec is just kexec jump that never comes back.
- Instead of using a swap page when moving data between
pages the page copy assembly routine has been modified
to exchange the data between the pages using registers.
- We walk the page list twice in machine_kexec() to
do and undo physical to virtual address conversion.
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/kernel/relocate_kernel.S b/arch/sh/kernel/relocate_kernel.S
index 2a6630b..fcc9934 100644
--- a/arch/sh/kernel/relocate_kernel.S
+++ b/arch/sh/kernel/relocate_kernel.S
@@ -4,6 +4,8 @@
*
* LANDISK/sh4 is supported. Maybe, SH archtecture works well.
*
+ * 2009-03-18 Magnus Damm - Added Kexec Jump support
+ *
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
@@ -17,14 +19,135 @@
/* r5 = reboot_code_buffer */
/* r6 = start_address */
- mov.l 10f,r8 /* PAGE_SIZE */
+ mov.l 10f, r0 /* PAGE_SIZE */
+ add r5, r0 /* setup new stack at end of control page */
- /* stack setting */
- add r8,r5
- mov r5,r15
+ /* save r15->r8 to new stack */
+ mov.l r15, @-r0
+ mov r0, r15
+ mov.l r14, @-r15
+ mov.l r13, @-r15
+ mov.l r12, @-r15
+ mov.l r11, @-r15
+ mov.l r10, @-r15
+ mov.l r9, @-r15
+ mov.l r8, @-r15
+ /* save other random registers */
+ sts.l macl, @-r15
+ sts.l mach, @-r15
+ stc.l gbr, @-r15
+ stc.l ssr, @-r15
+ stc.l sr, @-r15
+ sts.l pr, @-r15
+ stc.l spc, @-r15
+
+ /* switch to bank1 and save r7->r0 */
+ mov.l 12f, r9
+ stc sr, r8
+ or r9, r8
+ ldc r8, sr
+ mov.l r7, @-r15
+ mov.l r6, @-r15
+ mov.l r5, @-r15
+ mov.l r4, @-r15
+ mov.l r3, @-r15
+ mov.l r2, @-r15
+ mov.l r1, @-r15
+ mov.l r0, @-r15
+
+ /* switch to bank0 and save r7->r0 */
+ mov.l 12f, r9
+ not r9, r9
+ stc sr, r8
+ and r9, r8
+ ldc r8, sr
+ mov.l r7, @-r15
+ mov.l r6, @-r15
+ mov.l r5, @-r15
+ mov.l r4, @-r15
+ mov.l r3, @-r15
+ mov.l r2, @-r15
+ mov.l r1, @-r15
+ mov.l r0, @-r15
+
+ mov.l r4, @-r15 /* save indirection page again */
+
+ bsr swap_pages /* swap pages before jumping to new kernel */
+ nop
+
+ mova 11f, r0
+ mov.l r15, @r0 /* save pointer to stack */
+
+ jsr @r6 /* hand over control to new kernel */
+ nop
+
+ mov.l 11f, r15 /* get pointer to stack */
+ mov.l @r15+, r4 /* restore r4 to get indirection page */
+
+ bsr swap_pages /* swap pages back to previous state */
+ nop
+
+ /* make sure bank0 is active and restore r0->r7 */
+ mov.l 12f, r9
+ not r9, r9
+ stc sr, r8
+ and r9, r8
+ ldc r8, sr
+ mov.l @r15+, r0
+ mov.l @r15+, r1
+ mov.l @r15+, r2
+ mov.l @r15+, r3
+ mov.l @r15+, r4
+ mov.l @r15+, r5
+ mov.l @r15+, r6
+ mov.l @r15+, r7
+
+ /* switch to bank1 and restore r0->r7 */
+ mov.l 12f, r9
+ stc sr, r8
+ or r9, r8
+ ldc r8, sr
+ mov.l @r15+, r0
+ mov.l @r15+, r1
+ mov.l @r15+, r2
+ mov.l @r15+, r3
+ mov.l @r15+, r4
+ mov.l @r15+, r5
+ mov.l @r15+, r6
+ mov.l @r15+, r7
+
+ /* switch back to bank0 */
+ mov.l 12f, r9
+ not r9, r9
+ stc sr, r8
+ and r9, r8
+ ldc r8, sr
+
+ /* restore other random registers */
+ ldc.l @r15+, spc
+ lds.l @r15+, pr
+ ldc.l @r15+, sr
+ ldc.l @r15+, ssr
+ ldc.l @r15+, gbr
+ lds.l @r15+, mach
+ lds.l @r15+, macl
+
+ /* restore r8->r15 */
+ mov.l @r15+, r8
+ mov.l @r15+, r9
+ mov.l @r15+, r10
+ mov.l @r15+, r11
+ mov.l @r15+, r12
+ mov.l @r15+, r13
+ mov.l @r15+, r14
+ mov.l @r15+, r15
+ rts
+ nop
+
+swap_pages:
bra 1f
- mov r4,r0 /* cmd = indirection_page */
+ mov r4,r0 /* cmd = indirection_page */
0:
mov.l @r4+,r0 /* cmd = *ind++ */
@@ -37,52 +160,70 @@
tst #1,r0
bt 2f
bra 0b
- mov r2,r5
+ mov r2,r5
2: /* else if(cmd & IND_INDIRECTION) ind = addr */
tst #2,r0
bt 3f
bra 0b
- mov r2,r4
+ mov r2,r4
-3: /* else if(cmd & IND_DONE) goto 6 */
+3: /* else if(cmd & IND_DONE) return */
tst #4,r0
bt 4f
- bra 6f
- nop
+ rts
+ nop
4: /* else if(cmd & IND_SOURCE) memcpy(dst,addr,PAGE_SIZE) */
tst #8,r0
bt 0b
- mov r8,r3
+ mov.l 10f,r3 /* PAGE_SIZE */
shlr2 r3
shlr2 r3
5:
dt r3
- mov.l @r2+,r1 /* 16n+0 */
- mov.l r1,@r5
- add #4,r5
- mov.l @r2+,r1 /* 16n+4 */
- mov.l r1,@r5
- add #4,r5
- mov.l @r2+,r1 /* 16n+8 */
- mov.l r1,@r5
- add #4,r5
- mov.l @r2+,r1 /* 16n+12 */
- mov.l r1,@r5
- add #4,r5
+
+ /* regular kexec just overwrites the destination page
+ * with the contents of the source page.
+ * for the kexec jump case we need to swap the contents
+ * of the pages.
+ * to keep it simple swap the contents for both cases.
+ */
+ mov.l @(0, r2), r8
+ mov.l @(0, r5), r1
+ mov.l r8, @(0, r5)
+ mov.l r1, @(0, r2)
+
+ mov.l @(4, r2), r8
+ mov.l @(4, r5), r1
+ mov.l r8, @(4, r5)
+ mov.l r1, @(4, r2)
+
+ mov.l @(8, r2), r8
+ mov.l @(8, r5), r1
+ mov.l r8, @(8, r5)
+ mov.l r1, @(8, r2)
+
+ mov.l @(12, r2), r8
+ mov.l @(12, r5), r1
+ mov.l r8, @(12, r5)
+ mov.l r1, @(12, r2)
+
+ add #16,r5
+ add #16,r2
bf 5b
bra 0b
- nop
-6:
- jmp @r6
- nop
+ nop
.align 2
10:
.long PAGE_SIZE
+11:
+ .long 0
+12:
+ .long 0x20000000 ! RB=1
relocate_new_kernel_end: