4 files changed, 31 insertions, 2 deletions

diff --git a/arch/powerpc/boot/main.c b/arch/powerpc/boot/main.c
index 57d42d129033..78aaf4ffd7ab 100644
--- a/arch/powerpc/boot/main.c
+++ b/arch/powerpc/boot/main.c
@@ -232,8 +232,12 @@ void start(void)
                 console_ops.close();
 
         kentry = (kernel_entry_t) vmlinux.addr;
-        if (ft_addr)
-                kentry(ft_addr, 0, NULL);
+        if (ft_addr) {
+                if(platform_ops.kentry)
+                        platform_ops.kentry(ft_addr, vmlinux.addr);
+                else
+                        kentry(ft_addr, 0, NULL);
+        }
         else
                 kentry((unsigned long)initrd.addr, initrd.size,
                        loader_info.promptr);
diff --git a/arch/powerpc/boot/opal-calls.S b/arch/powerpc/boot/opal-calls.S
index ff2f1b97bc53..2a99fc9a3ccf 100644
--- a/arch/powerpc/boot/opal-calls.S
+++ b/arch/powerpc/boot/opal-calls.S
@@ -12,6 +12,19 @@
 
         .text
 
+        .globl opal_kentry
+opal_kentry:
+        /* r3 is the fdt ptr */
+        mtctr r4
+        li      r4, 0
+        li      r5, 0
+        li      r6, 0
+        li      r7, 0
+        ld      r11,opal@got(r2)
+        ld      r8,0(r11)
+        ld      r9,8(r11)
+        bctr
+
 #define OPAL_CALL(name, token)                          \
         .globl name;                                    \
 name:                                                   \
diff --git a/arch/powerpc/boot/opal.c b/arch/powerpc/boot/opal.c
index 1f37e1c1d6d8..d7b4fd47eb44 100644
--- a/arch/powerpc/boot/opal.c
+++ b/arch/powerpc/boot/opal.c
@@ -23,14 +23,25 @@ struct opal {
 
 static u32 opal_con_id;
 
+/* see opal-wrappers.S */
 int64_t opal_console_write(int64_t term_number, u64 *length, const u8 *buffer);
 int64_t opal_console_read(int64_t term_number, uint64_t *length, u8 *buffer);
 int64_t opal_console_write_buffer_space(uint64_t term_number, uint64_t *length);
 int64_t opal_console_flush(uint64_t term_number);
 int64_t opal_poll_events(uint64_t *outstanding_event_mask);
 
+void opal_kentry(unsigned long fdt_addr, void *vmlinux_addr);
+
 static int opal_con_open(void)
 {
+        /*
+         * When OPAL loads the boot kernel it stashes the OPAL base and entry
+         * address in r8 and r9 so the kernel can use the OPAL console
+         * before unflattening the devicetree. While executing the wrapper will
+         * probably trash r8 and r9 so this kentry hook restores them before
+         * entering the decompressed kernel.
+         */
+        platform_ops.kentry = opal_kentry;
         return 0;
 }
 
diff --git a/arch/powerpc/boot/ops.h b/arch/powerpc/boot/ops.h
index 309d1b127e96..fad1862f4b2d 100644
--- a/arch/powerpc/boot/ops.h
+++ b/arch/powerpc/boot/ops.h
@@ -30,6 +30,7 @@ struct platform_ops {
         void *  (*realloc)(void *ptr, unsigned long size);
         void    (*exit)(void);
         void *  (*vmlinux_alloc)(unsigned long size);
+        void    (*kentry)(unsigned long fdt_addr, void *vmlinux_addr);
 };
 extern struct platform_ops platform_ops;