ARM: 8805/2: remove unneeded naked function usage

The naked attribute is known to confuse some old gcc versions when
function arguments aren't explicitly listed as inline assembly operands
despite the gcc documentation. That resulted in commit 9a40ac86152c
("ARM: 6164/1: Add kto and kfrom to input operands list.").

Yet that commit has problems of its own by having assembly operand
constraints completely wrong. If the generated code has been OK since
then, it is due to luck rather than correctness. So this patch also
provides proper assembly operand constraints, and removes two instances
of redundant register usages in the implementation while at it.

Inspection of the generated code with this patch doesn't show any
obvious quality degradation either, so not relying on __naked at all
will make the code less fragile, and avoid some issues with clang.

The only remaining __naked instances (excluding the kprobes test cases)
are exynos_pm_power_up_setup(), tc2_pm_power_up_setup() and

cci_enable_port_for_self(. But in the first two cases, only the function
address is used by the compiler with no chance of inlining it by
mistake, and the third case is called from assembly code only. And the
fact that no stack is available when the corresponding code is executed
does warrant the __naked usage in those cases.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Tested-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 31 insertions, 40 deletions

diff --git a/arch/arm/mm/copypage-xsc3.c b/arch/arm/mm/copypage-xsc3.c
index 03a2042aced5..55cbc3a89d85 100644
--- a/arch/arm/mm/copypage-xsc3.c
+++ b/arch/arm/mm/copypage-xsc3.c
@@ -21,53 +21,46 @@
 
 /*
  * XSC3 optimised copy_user_highpage
- *  r0 = destination
- *  r1 = source
  *
  * The source page may have some clean entries in the cache already, but we
  * can safely ignore them - break_cow() will flush them out of the cache
  * if we eventually end up using our copied page.
  *
  */
-static void __naked
-xsc3_mc_copy_user_page(void *kto, const void *kfrom)
+static void xsc3_mc_copy_user_page(void *kto, const void *kfrom)
 {
-	asm("\
-	stmfd	sp!, {r4, r5, lr}		\n\
-	mov	lr, %2				\n\
-						\n\
-	pld	[r1, #0]			\n\
-	pld	[r1, #32]			\n\
-1:	pld	[r1, #64]			\n\
-	pld	[r1, #96]			\n\
+	int tmp;
+
+	asm volatile ("\
+	pld	[%1, #0]			\n\
+	pld	[%1, #32]			\n\
+1:	pld	[%1, #64]			\n\
+	pld	[%1, #96]			\n\
 						\n\
-2:	ldrd	r2, [r1], #8			\n\
-	mov	ip, r0				\n\
-	ldrd	r4, [r1], #8			\n\
-	mcr	p15, 0, ip, c7, c6, 1		@ invalidate\n\
-	strd	r2, [r0], #8			\n\
-	ldrd	r2, [r1], #8			\n\
-	strd	r4, [r0], #8			\n\
-	ldrd	r4, [r1], #8			\n\
-	strd	r2, [r0], #8			\n\
-	strd	r4, [r0], #8			\n\
-	ldrd	r2, [r1], #8			\n\
-	mov	ip, r0				\n\
-	ldrd	r4, [r1], #8			\n\
-	mcr	p15, 0, ip, c7, c6, 1		@ invalidate\n\
-	strd	r2, [r0], #8			\n\
-	ldrd	r2, [r1], #8			\n\
-	subs	lr, lr, #1			\n\
-	strd	r4, [r0], #8			\n\
-	ldrd	r4, [r1], #8			\n\
-	strd	r2, [r0], #8			\n\
-	strd	r4, [r0], #8			\n\
+2:	ldrd	r2, [%1], #8			\n\
+	ldrd	r4, [%1], #8			\n\
+	mcr	p15, 0, %0, c7, c6, 1		@ invalidate\n\
+	strd	r2, [%0], #8			\n\
+	ldrd	r2, [%1], #8			\n\
+	strd	r4, [%0], #8			\n\
+	ldrd	r4, [%1], #8			\n\
+	strd	r2, [%0], #8			\n\
+	strd	r4, [%0], #8			\n\
+	ldrd	r2, [%1], #8			\n\
+	ldrd	r4, [%1], #8			\n\
+	mcr	p15, 0, %0, c7, c6, 1		@ invalidate\n\
+	strd	r2, [%0], #8			\n\
+	ldrd	r2, [%1], #8			\n\
+	subs	%2, %2, #1			\n\
+	strd	r4, [%0], #8			\n\
+	ldrd	r4, [%1], #8			\n\
+	strd	r2, [%0], #8			\n\
+	strd	r4, [%0], #8			\n\
 	bgt	1b				\n\
-	beq	2b				\n\
-						\n\
-	ldmfd	sp!, {r4, r5, pc}"
-	:
-	: "r" (kto), "r" (kfrom), "I" (PAGE_SIZE / 64 - 1));
+	beq	2b				"
+	: "+&r" (kto), "+&r" (kfrom), "=&r" (tmp)
+	: "2" (PAGE_SIZE / 64 - 1)
+	: "r2", "r3", "r4", "r5");
 }
 
 void xsc3_mc_copy_user_highpage(struct page *to, struct page *from,
@@ -85,8 +78,6 @@ void xsc3_mc_copy_user_highpage(struct page *to, struct page *from,
 
 /*
  * XScale optimised clear_user_page
- *  r0 = destination
- *  r1 = virtual user address of ultimate destination page
  */
 void xsc3_mc_clear_user_highpage(struct page *page, unsigned long vaddr)
 {