[PATCH] MIPS: Enable GCOV

[Xingxing Su]

Enable gcov profiling of the entire kernel on mips. Required changes
include disabling profiling for:

* arch/kernel/boot/compressed: not linked to main kernel.

Lightly tested on Loongson 3A3000 an 3A4000, seems to work as expected.

without "GCOV_PROFILE := n" in compressed Makefile,
build errors as follows:
...
ld: arch/mips/boot/compressed/string.o:(.data+0x88):
 undefined reference to `__gcov_merge_add'
ld: arch/mips/boot/compressed/string.o:
 in function `_GLOBAL__sub_I_00100_0_memcpy':
string.c:(.text.startup+0x4): undefined reference to `__gcov_init'
ld: arch/mips/boot/compressed/string.o:
 in function `_GLOBAL__sub_D_00100_1_memcpy':
string.c:(.text.exit+0x0): undefined reference to `__gcov_exit'
...

Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxxx>
Signed-off-by: Xingxing Su <suxingxing@xxxxxxxxxxx>
---
 arch/mips/Kconfig                  | 1 +
 arch/mips/boot/compressed/Makefile | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 2000bb2..52664a30 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -9,6 +9,7 @@ config MIPS
 	select ARCH_HAS_PTE_SPECIAL if !(32BIT && CPU_HAS_RIXI)
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_SUPPORTS_UPROBES
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF if 64BIT
diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
index d665118..405b47a 100644
--- a/arch/mips/boot/compressed/Makefile
+++ b/arch/mips/boot/compressed/Makefile
@@ -36,6 +36,7 @@ KBUILD_AFLAGS := $(KBUILD_AFLAGS) -D__ASSEMBLY__ \
 
 # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
 KCOV_INSTRUMENT		:= n
+GCOV_PROFILE := n
 
 # decompressor objects (linked with vmlinuz)
 vmlinuzobjs-y := $(obj)/head.o $(obj)/decompress.o $(obj)/string.o
-- 
2.1.0