ARM: 6518/1: kexec: Fix crash_setup_regs() for ARMv7 and CONFIG_THUMB2_KERNEL

  * Fix kexec build failure with CONFIG_THUMB2_KERNEL.

  * Avoids deprecated/forbidden sp and pc usage in for ARMv7
    onwards, retaining compatibility with older architecture
    versions.

  * The pc value saved to newregs is now aligned on a predictable
    instruction boundary.

    (stmia { ... pc } or str pc has implementation-defined results
    in most versions of the ARM architecutre, and is prohibited
    (unpredictable) in Thumb-2.)

  * Switch to named inline asm arguments (else I get readily
    confused ...)

    The resulting code should be compatible with all architecture
    versions >= v3, with or without CONFIG_THUMB2_KERNEL.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Tested-by: Mika Westerberg <mika.westerberg@iki.fi>
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/kexec.h

@@ -33,10 +33,20 @@ static inline void crash_setup_regs(struct pt_regs *newregs,
 	if (oldregs) {
 		memcpy(newregs, oldregs, sizeof(*newregs));
 	} else {
-		__asm__ __volatile__ ("stmia %0, {r0 - r15}"
-				      : : "r" (&newregs->ARM_r0) : "memory");
-		__asm__ __volatile__ ("mrs %0, cpsr"
-				      : "=r" (newregs->ARM_cpsr));
+		__asm__ __volatile__ (
+			"stmia	%[regs_base], {r0-r12}\n\t"
+			"mov	%[_ARM_sp], sp\n\t"
+			"str	lr, %[_ARM_lr]\n\t"
+			"adr	%[_ARM_pc], 1f\n\t"
+			"mrs	%[_ARM_cpsr], cpsr\n\t"
+		"1:"
+			: [_ARM_pc] "=r" (newregs->ARM_pc),
+			  [_ARM_cpsr] "=r" (newregs->ARM_cpsr),
+			  [_ARM_sp] "=r" (newregs->ARM_sp),
+			  [_ARM_lr] "=o" (newregs->ARM_lr)
+			: [regs_base] "r" (&newregs->ARM_r0)
+			: "memory"
+		);
 	}
 }