MIPS: Call relocate_kernel if CONFIG_RELOCATABLE=y

If CONFIG_RELOCATABLE is enabled, call relocate_kernel.

This function will return the entry point of the relocated kernel if
copy/relocate is sucessful or the original entry point if not. The stack
pointer must then be pointed into the new image.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Jonas Gorski <jogo@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: kernel-hardening@lists.openwall.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12984/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
index 4e4cc5b..7dc0433 100644 (file)
--- a/arch/mips/kernel/head.S
+++ b/arch/mips/kernel/head.S
@@ -132,7 +132,27 @@ not_found:
        set_saved_sp    sp, t0, t1
        PTR_SUBU        sp, 4 * SZREG           # init stack pointer
 
+#ifdef CONFIG_RELOCATABLE
+       /* Copy kernel and apply the relocations */
+       jal             relocate_kernel
+
+       /* Repoint the sp into the new kernel image */
+       PTR_LI          sp, _THREAD_SIZE - 32 - PT_SIZE
+       PTR_ADDU        sp, $28
+       set_saved_sp    sp, t0, t1
+       PTR_SUBU        sp, 4 * SZREG           # init stack pointer
+
+       /*
+        * relocate_kernel returns the entry point either
+        * in the relocated kernel or the original if for
+        * some reason relocation failed - jump there now
+        * with instruction hazard barrier because of the
+        * newly sync'd icache.
+        */
+       jr.hb           v0
+#else
        j               start_kernel
+#endif
        END(kernel_entry)
 
 #ifdef CONFIG_SMP