MIPS: do not compile generic functions for CONFIG_CAVIUM_OCTEON_SOC

MIPS provides multiple definitions for the following functions:

fw_init_cmdline
__delay
__udelay
__ndelay
memmove
__rmemcpy
memcpy
__copy_user

The generic ones are defined in lib-y objects, which are overridden by
the Octeon ones when CONFIG_CAVIUM_OCTEON_SOC is enabled.

The use of EXPORT_SYMBOL in static libraries potentially causes a
problem for the llvm linker [1]. So, I want to forcibly link lib-y
objects to vmlinux when CONFIG_MODULES=y.

As a groundwork, we must fix multiple definitions that have previously
been hidden by lib-y.

If you look at lib/string.c, arch can define __HAVE_ARCH_* to opt out
the generic implementation.

Similarly, this commit adds CONFIG_HAVE_PLAT_* to allow a platform
to opt out the MIPS generic code.

[1]: https://github.com/ClangBuiltLinux/linux/issues/515

Reported-by: kbuild test robot <[e-mail]>
Signed-off-by: Masahiro Yamada <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/Kconfig

···
 	select SYS_HAS_EARLY_PRINTK
 	select SYS_HAS_CPU_CAVIUM_OCTEON
 	select HAVE_PCI
+	select HAVE_PLAT_DELAY
+	select HAVE_PLAT_FW_INIT_CMDLINE
+	select HAVE_PLAT_MEMCPY
 	select ZONE_DMA32
 	select HOLES_IN_ZONE
 	select GPIOLIB
···
 config GENERIC_ISA_DMA_SUPPORT_BROKEN
 	bool
 	select GENERIC_ISA_DMA
+
+config HAVE_PLAT_DELAY
+	bool
+
+config HAVE_PLAT_FW_INIT_CMDLINE
+	bool
+
+config HAVE_PLAT_MEMCPY
+	bool
 
 config ISA_DMA_API
 	bool

arch/mips/fw/lib/cmdline.c

···
 int *_fw_argv;
 int *_fw_envp;
 
+#ifndef CONFIG_HAVE_PLAT_FW_INIT_CMDLINE
 void __init fw_init_cmdline(void)
 {
 	int i;
···
 			strlcat(arcs_cmdline, " ", COMMAND_LINE_SIZE);
 	}
 }
+#endif
 
 char * __init fw_getcmdline(void)
 {

arch/mips/lib/delay.c

···
 #define GCC_DADDI_IMM_ASM() "r"
 #endif
 
+#ifndef CONFIG_HAVE_PLAT_DELAY
+
 void __delay(unsigned long loops)
 {
 	__asm__ __volatile__ (
···
 	__delay((ns * 0x00000005ull * HZ * lpj) >> 32);
 }
 EXPORT_SYMBOL(__ndelay);
+
+#endif

arch/mips/lib/memcpy.S

···
 	 nop
 	.endm
 
+#ifndef CONFIG_HAVE_PLAT_MEMCPY
 	.align	5
 LEAF(memmove)
 EXPORT_SYMBOL(memmove)
···
 EXPORT_SYMBOL(__copy_user)
 	/* Legacy Mode, user <-> user */
 	__BUILD_COPY_USER LEGACY_MODE USEROP USEROP
+
+#endif
 
 #ifdef CONFIG_EVA