ARM: 9393/1: mm: Use conditionals for CFI branches

Commit 9385/2 introduced a few branches inside function
prototypes when using CFI in order to deal with the situation
where CFI inserts a few bytes of function information in front
of the symbol.

This is not good for older CPUs where every cycle counts.

Commit 9386/2 alleviated the situation a bit by using aliases
for the cache functions with identical signatures.

This leaves the coherent cache flush functions
*_coherent_kern_range() with these branches to the corresponing
*_coherent_user_range() around, since their return type differ and
they therefore cannot be aliased.

Solve this by a simple ifdef so at least we can use fallthroughs
when compiling without CFI enabled.

Link: https://lore.kernel.org/linux-arm-kernel/Zi+e9M%2Ff5b%2FSto9H@shell.armlinux.org.uk/

Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Author: linusw

arch/arm/mm/cache-fa.S

@@ -112,7 +112,9 @@ SYM_FUNC_END(fa_flush_user_cache_range)
  *	- end	 - virtual end address
  */
 SYM_TYPED_FUNC_START(fa_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	fa_coherent_user_range
+#endif
 SYM_FUNC_END(fa_coherent_kern_range)
 
 /*

arch/arm/mm/cache-v4.S

@@ -104,7 +104,9 @@ SYM_FUNC_END(v4_coherent_user_range)
  *	- size	- region size
  */
 SYM_TYPED_FUNC_START(v4_flush_kern_dcache_area)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	v4_dma_flush_range
+#endif
 SYM_FUNC_END(v4_flush_kern_dcache_area)
 
 /*

arch/arm/mm/cache-v4wb.S

@@ -136,7 +136,9 @@ SYM_FUNC_END(v4wb_flush_user_cache_range)
  */
 SYM_TYPED_FUNC_START(v4wb_flush_kern_dcache_area)
 	add	r1, r0, r1
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	v4wb_coherent_user_range
+#endif
 SYM_FUNC_END(v4wb_flush_kern_dcache_area)
 
 /*
@@ -150,7 +152,9 @@ SYM_FUNC_END(v4wb_flush_kern_dcache_area)
  *	- end	 - virtual end address
  */
 SYM_TYPED_FUNC_START(v4wb_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	v4wb_coherent_user_range
+#endif
 SYM_FUNC_END(v4wb_coherent_kern_range)
 
 /*

arch/arm/mm/cache-v4wt.S

@@ -108,7 +108,9 @@ SYM_FUNC_END(v4wt_flush_user_cache_range)
  *	- end	 - virtual end address
  */
 SYM_TYPED_FUNC_START(v4wt_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	v4wt_coherent_user_range
+#endif
 SYM_FUNC_END(v4wt_coherent_kern_range)
 
 /*

arch/arm/mm/cache-v6.S

@@ -117,7 +117,9 @@ SYM_FUNC_END(v6_flush_user_cache_range)
  *	- the Icache does not read data from the write buffer
  */
 SYM_TYPED_FUNC_START(v6_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	v6_coherent_user_range
+#endif
 SYM_FUNC_END(v6_coherent_kern_range)
 
 /*

arch/arm/mm/cache-v7.S

@@ -261,7 +261,9 @@ SYM_FUNC_END(v7_flush_user_cache_range)
  *	- the Icache does not read data from the write buffer
  */
 SYM_TYPED_FUNC_START(v7_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	v7_coherent_user_range
+#endif
 SYM_FUNC_END(v7_coherent_kern_range)
 
 /*

arch/arm/mm/cache-v7m.S

@@ -286,7 +286,9 @@ SYM_FUNC_END(v7m_flush_user_cache_range)
  *	- the Icache does not read data from the write buffer
  */
 SYM_TYPED_FUNC_START(v7m_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	v7m_coherent_user_range
+#endif
 SYM_FUNC_END(v7m_coherent_kern_range)
 
 /*

arch/arm/mm/proc-arm1020.S

@@ -203,7 +203,9 @@ SYM_FUNC_END(arm1020_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm1020_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm1020_coherent_user_range
+#endif
 SYM_FUNC_END(arm1020_coherent_kern_range)
 
 /*

arch/arm/mm/proc-arm1020e.S

@@ -200,7 +200,9 @@ SYM_FUNC_END(arm1020e_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm1020e_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm1020e_coherent_user_range
+#endif
 SYM_FUNC_END(arm1020e_coherent_kern_range)
 
 /*

arch/arm/mm/proc-arm1022.S

@@ -199,7 +199,9 @@ SYM_FUNC_END(arm1022_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm1022_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm1022_coherent_user_range
+#endif
 SYM_FUNC_END(arm1022_coherent_kern_range)
 
 /*

arch/arm/mm/proc-arm1026.S

@@ -194,7 +194,9 @@ SYM_FUNC_END(arm1026_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm1026_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm1026_coherent_user_range
+#endif
 SYM_FUNC_END(arm1026_coherent_kern_range)
 
 /*

arch/arm/mm/proc-arm920.S

@@ -180,7 +180,9 @@ SYM_FUNC_END(arm920_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm920_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm920_coherent_user_range
+#endif
 SYM_FUNC_END(arm920_coherent_kern_range)
 
 /*

arch/arm/mm/proc-arm922.S

@@ -182,7 +182,9 @@ SYM_FUNC_END(arm922_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm922_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm922_coherent_user_range
+#endif
 SYM_FUNC_END(arm922_coherent_kern_range)
 
 /*

arch/arm/mm/proc-arm925.S

@@ -229,7 +229,9 @@ SYM_FUNC_END(arm925_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm925_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm925_coherent_user_range
+#endif
 SYM_FUNC_END(arm925_coherent_kern_range)
 
 /*

arch/arm/mm/proc-arm926.S

@@ -192,7 +192,9 @@ SYM_FUNC_END(arm926_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm926_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm926_coherent_user_range
+#endif
 SYM_FUNC_END(arm926_coherent_kern_range)
 
 /*

arch/arm/mm/proc-arm940.S

@@ -153,7 +153,9 @@ SYM_FUNC_END(arm940_coherent_kern_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm940_coherent_user_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm940_flush_kern_dcache_area
+#endif
 SYM_FUNC_END(arm940_coherent_user_range)
 
 /*

arch/arm/mm/proc-arm946.S

@@ -173,7 +173,9 @@ SYM_FUNC_END(arm946_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(arm946_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	arm946_coherent_user_range
+#endif
 SYM_FUNC_END(arm946_coherent_kern_range)
 
 /*

arch/arm/mm/proc-feroceon.S

@@ -208,7 +208,9 @@ SYM_FUNC_END(feroceon_flush_user_cache_range)
  */
 	.align	5
 SYM_TYPED_FUNC_START(feroceon_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	feroceon_coherent_user_range
+#endif
 SYM_FUNC_END(feroceon_coherent_kern_range)
 
 /*

arch/arm/mm/proc-mohawk.S

@@ -163,7 +163,9 @@ SYM_FUNC_END(mohawk_flush_user_cache_range)
  *	- end	- virtual end address
  */
 SYM_TYPED_FUNC_START(mohawk_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	mohawk_coherent_user_range
+#endif
 SYM_FUNC_END(mohawk_coherent_kern_range)
 
 /*

arch/arm/mm/proc-xsc3.S

@@ -223,7 +223,9 @@ SYM_FUNC_END(xsc3_flush_user_cache_range)
  *	it also trashes the mini I-cache used by JTAG debuggers.
  */
 SYM_TYPED_FUNC_START(xsc3_coherent_kern_range)
+#ifdef CONFIG_CFI_CLANG /* Fallthrough if !CFI */
 	b	xsc3_coherent_user_range
+#endif
 SYM_FUNC_END(xsc3_coherent_kern_range)
 
 SYM_TYPED_FUNC_START(xsc3_coherent_user_range)