ARM: 9385/2: mm: Type-annotate all cache assembly routines

Tag all references to assembly functions with SYM_TYPED_FUNC_START()
and SYM_FUNC_END() so they also become CFI-safe.

When we add SYM_TYPED_FUNC_START() to assembly calls, a function
prototype signature will be emitted into the object file at
(pc-4) at the call site, so that the KCFI runtime check can compare
this to the expected call. Example:

8011ae38:       a540670c        .word   0xa540670c

8011ae3c <v7_flush_icache_all>:
8011ae3c:       e3a00000        mov     r0, #0
8011ae40:       ee070f11        mcr     15, 0, r0, cr7, cr1, {0}
8011ae44:       e12fff1e        bx      lr

This means no "fallthrough" code can enter a SYM_TYPED_FUNC_START()
call from above it: there will be a function prototype signature
there, so those are consistently converted to a branch or ret lr
depending on context.

Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

1 files changed, 23 insertions, 18 deletions

diff --git a/arch/arm/mm/cache-v6.S b/arch/arm/mm/cache-v6.S
index 44211d8a296f..5c7549a49db5 100644
--- a/arch/arm/mm/cache-v6.S
+++ b/arch/arm/mm/cache-v6.S
@@ -8,6 +8,7 @@
  */
 #include <linux/linkage.h>
 #include <linux/init.h>
+#include <linux/cfi_types.h>
 #include <asm/assembler.h>
 #include <asm/errno.h>
 #include <asm/unwind.h>
@@ -34,7 +35,7 @@
  *	r0 - set to 0
  *	r1 - corrupted
  */
-ENTRY(v6_flush_icache_all)
+SYM_TYPED_FUNC_START(v6_flush_icache_all)
 	mov	r0, #0
 #ifdef CONFIG_ARM_ERRATA_411920
 	mrs	r1, cpsr
@@ -51,7 +52,7 @@ ENTRY(v6_flush_icache_all)
 	mcr	p15, 0, r0, c7, c5, 0		@ invalidate I-cache
 #endif
 	ret	lr
-ENDPROC(v6_flush_icache_all)
+SYM_FUNC_END(v6_flush_icache_all)
 
 /*
  *	v6_flush_cache_all()
@@ -60,7 +61,7 @@ ENDPROC(v6_flush_icache_all)
  *
  *	It is assumed that:
  */
-ENTRY(v6_flush_kern_cache_all)
+SYM_TYPED_FUNC_START(v6_flush_kern_cache_all)
 	mov	r0, #0
 #ifdef HARVARD_CACHE
 	mcr	p15, 0, r0, c7, c14, 0		@ D cache clean+invalidate
@@ -73,6 +74,7 @@ ENTRY(v6_flush_kern_cache_all)
 	mcr	p15, 0, r0, c7, c15, 0		@ Cache clean+invalidate
 #endif
 	ret	lr
+SYM_FUNC_END(v6_flush_kern_cache_all)
 
 /*
  *	v6_flush_cache_all()
@@ -81,8 +83,9 @@ ENTRY(v6_flush_kern_cache_all)
  *
  *	- mm    - mm_struct describing address space
  */
-ENTRY(v6_flush_user_cache_all)
-	/*FALLTHROUGH*/
+SYM_TYPED_FUNC_START(v6_flush_user_cache_all)
+	ret	lr
+SYM_FUNC_END(v6_flush_user_cache_all)
 
 /*
  *	v6_flush_cache_range(start, end, flags)
@@ -96,8 +99,9 @@ ENTRY(v6_flush_user_cache_all)
  *	It is assumed that:
  *	- we have a VIPT cache.
  */
-ENTRY(v6_flush_user_cache_range)
+SYM_TYPED_FUNC_START(v6_flush_user_cache_range)
 	ret	lr
+SYM_FUNC_END(v6_flush_user_cache_range)
 
 /*
  *	v6_coherent_kern_range(start,end)
@@ -112,8 +116,9 @@ ENTRY(v6_flush_user_cache_range)
  *	It is assumed that:
  *	- the Icache does not read data from the write buffer
  */
-ENTRY(v6_coherent_kern_range)
-	/* FALLTHROUGH */
+SYM_TYPED_FUNC_START(v6_coherent_kern_range)
+	b	v6_coherent_user_range
+SYM_FUNC_END(v6_coherent_kern_range)
 
 /*
  *	v6_coherent_user_range(start,end)
@@ -128,7 +133,7 @@ ENTRY(v6_coherent_kern_range)
  *	It is assumed that:
  *	- the Icache does not read data from the write buffer
  */
-ENTRY(v6_coherent_user_range)
+SYM_TYPED_FUNC_START(v6_coherent_user_range)
  UNWIND(.fnstart		)
 #ifdef HARVARD_CACHE
 	bic	r0, r0, #CACHE_LINE_SIZE - 1
@@ -159,8 +164,7 @@ ENTRY(v6_coherent_user_range)
 	mov	r0, #-EFAULT
 	ret	lr
  UNWIND(.fnend		)
-ENDPROC(v6_coherent_user_range)
-ENDPROC(v6_coherent_kern_range)
+SYM_FUNC_END(v6_coherent_user_range)
 
 /*
  *	v6_flush_kern_dcache_area(void *addr, size_t size)
@@ -171,7 +175,7 @@ ENDPROC(v6_coherent_kern_range)
  *	- addr	- kernel address
  *	- size	- region size
  */
-ENTRY(v6_flush_kern_dcache_area)
+SYM_TYPED_FUNC_START(v6_flush_kern_dcache_area)
 	add	r1, r0, r1
 	bic	r0, r0, #D_CACHE_LINE_SIZE - 1
 1:
@@ -188,7 +192,7 @@ ENTRY(v6_flush_kern_dcache_area)
 	mcr	p15, 0, r0, c7, c10, 4
 #endif
 	ret	lr
-
+SYM_FUNC_END(v6_flush_kern_dcache_area)
 
 /*
  *	v6_dma_inv_range(start,end)
@@ -253,7 +257,7 @@ v6_dma_clean_range:
  *	- start   - virtual start address of region
  *	- end     - virtual end address of region
  */
-ENTRY(v6_dma_flush_range)
+SYM_TYPED_FUNC_START(v6_dma_flush_range)
 	bic	r0, r0, #D_CACHE_LINE_SIZE - 1
 1:
 #ifdef HARVARD_CACHE
@@ -267,6 +271,7 @@ ENTRY(v6_dma_flush_range)
 	mov	r0, #0
 	mcr	p15, 0, r0, c7, c10, 4		@ drain write buffer
 	ret	lr
+SYM_FUNC_END(v6_dma_flush_range)
 
 /*
  *	dma_map_area(start, size, dir)
@@ -274,12 +279,12 @@ ENTRY(v6_dma_flush_range)
  *	- size	- size of region
  *	- dir	- DMA direction
  */
-ENTRY(v6_dma_map_area)
+SYM_TYPED_FUNC_START(v6_dma_map_area)
 	add	r1, r1, r0
 	teq	r2, #DMA_FROM_DEVICE
 	beq	v6_dma_inv_range
 	b	v6_dma_clean_range
-ENDPROC(v6_dma_map_area)
+SYM_FUNC_END(v6_dma_map_area)
 
 /*
  *	dma_unmap_area(start, size, dir)
@@ -287,12 +292,12 @@ ENDPROC(v6_dma_map_area)
  *	- size	- size of region
  *	- dir	- DMA direction
  */
-ENTRY(v6_dma_unmap_area)
+SYM_TYPED_FUNC_START(v6_dma_unmap_area)
 	add	r1, r1, r0
 	teq	r2, #DMA_TO_DEVICE
 	bne	v6_dma_inv_range
 	ret	lr
-ENDPROC(v6_dma_unmap_area)
+SYM_FUNC_END(v6_dma_unmap_area)
 
 	.globl	v6_flush_kern_cache_louis
 	.equ	v6_flush_kern_cache_louis, v6_flush_kern_cache_all