[PATCH 2/4] ppc32/kprobe: introduce copy_exc_stack

[Tiejun Chen]

We need a copy mechanism to migrate exception stack. But looks copy_page()
already implement this well so we can complete copy_exc_stack() based on
that directly.

Signed-off-by: Tiejun Chen <tiejun.chen at windriver.com>
---
 arch/powerpc/include/asm/page_32.h |    1 +
 arch/powerpc/kernel/misc_32.S      |   16 +++++++++++++++-
 arch/powerpc/kernel/ppc_ksyms.c    |    1 +
 3 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/page_32.h b/arch/powerpc/include/asm/page_32.h
index 68d73b2..2c1fd84 100644
--- a/arch/powerpc/include/asm/page_32.h
+++ b/arch/powerpc/include/asm/page_32.h
@@ -40,6 +40,7 @@ struct page;
 extern void clear_pages(void *page, int order);
 static inline void clear_page(void *page) { clear_pages(page, 0); }
 extern void copy_page(void *to, void *from);
+extern void copy_exc_stack(void *to, void *from);
 
 #include <asm-generic/getorder.h>
 
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 998a100..aa02545 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -527,7 +527,7 @@ _GLOBAL(clear_pages)
 	stw	r8,12(r3);	\
 	stwu	r9,16(r3)
 
-_GLOBAL(copy_page)
+ready_copy:
 	addi	r3,r3,-4
 	addi	r4,r4,-4
 
@@ -544,7 +544,21 @@ _GLOBAL(copy_page)
 	dcbt	r5,r4
 	li	r11,L1_CACHE_BYTES+4
 #endif /* MAX_COPY_PREFETCH */
+	blr
+
+_GLOBAL(copy_exc_stack)
+	mflr	r12
+	bl	ready_copy
+	mtlr	r12
+	li	r0,INT_FRAME_SIZE/L1_CACHE_BYTES - MAX_COPY_PREFETCH
+	b	go_copy
+
+_GLOBAL(copy_page)
+	mflr	r12
+	bl	ready_copy
+	mtlr	r12
 	li	r0,PAGE_SIZE/L1_CACHE_BYTES - MAX_COPY_PREFETCH
+go_copy:
 	crclr	4*cr0+eq
 2:
 	mtctr	r0
diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index f5ae872..2223daf 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -88,6 +88,7 @@ EXPORT_SYMBOL(__clear_user);
 EXPORT_SYMBOL(__strncpy_from_user);
 EXPORT_SYMBOL(__strnlen_user);
 EXPORT_SYMBOL(copy_page);
+EXPORT_SYMBOL(copy_exc_stack);
 
 #if defined(CONFIG_PCI) && defined(CONFIG_PPC32)
 EXPORT_SYMBOL(isa_io_base);
-- 
1.5.6