MIPS: kdump: Add support

[ralf@linux-mips.org: Original patch by Maxim Uvarov <muvarov@gmail.com>
with plenty of further shining, polishing, debugging and testing by me.]

Signed-off-by: Maxim Uvarov <muvarov@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: kexec@lists.infradead.org
Cc: horms@verge.net.au
Patchwork: https://patchwork.linux-mips.org/patch/1025/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 87 insertions, 1 deletions

diff --git a/arch/mips/kernel/relocate_kernel.S b/arch/mips/kernel/relocate_kernel.S
index 87481f916a61..0b108587f065 100644
--- a/arch/mips/kernel/relocate_kernel.S
+++ b/arch/mips/kernel/relocate_kernel.S
@@ -15,6 +15,11 @@
 #include <asm/addrspace.h>
 
 LEAF(relocate_new_kernel)
+	PTR_L a0,	arg0
+	PTR_L a1,	arg1
+	PTR_L a2,	arg2
+	PTR_L a3,	arg3
+
 	PTR_L		s0, kexec_indirection_page
 	PTR_L		s1, kexec_start_address
 
@@ -26,7 +31,6 @@ process_entry:
 	and		s3, s2, 0x1
 	beq		s3, zero, 1f
 	and		s4, s2, ~0x1	/* store destination addr in s4 */
-	move		a0, s4
 	b		process_entry
 
 1:
@@ -60,10 +64,92 @@ copy_word:
 	b		process_entry
 
 done:
+#ifdef CONFIG_SMP
+	/* kexec_flag reset is signal to other CPUs what kernel
+	   was moved to it's location. Note - we need relocated address
+	   of kexec_flag.  */
+
+	bal		1f
+ 1: 	move		t1,ra;
+	PTR_LA		t2,1b
+	PTR_LA		t0,kexec_flag
+	PTR_SUB		t0,t0,t2;
+	PTR_ADD		t0,t1,t0;
+	LONG_S		zero,(t0)
+#endif
+
+	sync
 	/* jump to kexec_start_address */
 	j		s1
 	END(relocate_new_kernel)
 
+#ifdef CONFIG_SMP
+/*
+ * Other CPUs should wait until code is relocated and
+ * then start at entry (?) point.
+ */
+LEAF(kexec_smp_wait)
+	PTR_L		a0, s_arg0
+	PTR_L		a1, s_arg1
+	PTR_L		a2, s_arg2
+	PTR_L		a3, s_arg3
+	PTR_L		s1, kexec_start_address
+
+	/* Non-relocated address works for args and kexec_start_address ( old
+	 * kernel is not overwritten). But we need relocated address of
+	 * kexec_flag.
+	 */
+
+	bal		1f
+1:	move		t1,ra;
+	PTR_LA		t2,1b
+	PTR_LA		t0,kexec_flag
+	PTR_SUB		t0,t0,t2;
+	PTR_ADD		t0,t1,t0;
+
+1:	LONG_L		s0, (t0)
+	bne		s0, zero,1b
+
+	sync
+	j		s1
+	END(kexec_smp_wait)
+#endif
+
+#ifdef __mips64
+       /* all PTR's must be aligned to 8 byte in 64-bit mode */
+       .align  3
+#endif
+
+/* All parameters to new kernel are passed in registers a0-a3.
+ * kexec_args[0..3] are uses to prepare register values.
+ */
+
+kexec_args:
+	EXPORT(kexec_args)
+arg0:	PTR		0x0
+arg1:	PTR		0x0
+arg2:	PTR		0x0
+arg3:	PTR		0x0
+	.size	kexec_args,PTRSIZE*4
+
+#ifdef CONFIG_SMP
+/*
+ * Secondary CPUs may have different kernel parameters in
+ * their registers a0-a3. secondary_kexec_args[0..3] are used
+ * to prepare register values.
+ */
+secondary_kexec_args:
+	EXPORT(secondary_kexec_args)
+s_arg0:	PTR		0x0
+s_arg1:	PTR		0x0
+s_arg2:	PTR		0x0
+s_arg3:	PTR		0x0
+	.size	secondary_kexec_args,PTRSIZE*4
+kexec_flag:
+	LONG		0x1
+
+#endif
+
 kexec_start_address:
 	EXPORT(kexec_start_address)
 	PTR		0x0