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authorNathan Chancellor <nathan@kernel.org>2021-03-25 15:38:06 -0700
committerPalmer Dabbelt <palmerdabbelt@google.com>2021-04-26 08:25:01 -0700
commit7ce04771503074a7de7f539cc43f5e1b385cb99b (patch)
treed2d06cb1edf70b93164d1bfedd174718f4bc77c1 /arch/riscv
parent2f095504f4b9cf75856d6a9cf90299cf75aa46c5 (diff)
downloadlinux-7ce04771503074a7de7f539cc43f5e1b385cb99b.tar.bz2
riscv: Workaround mcount name prior to clang-13
Prior to clang 13.0.0, the RISC-V name for the mcount symbol was "mcount", which differs from the GCC version of "_mcount", which results in the following errors: riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_level': main.c:(.text+0xe): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_start': main.c:(.text+0x4e): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_finish': main.c:(.text+0x92): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `.LBB32_28': main.c:(.text+0x30c): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `free_initmem': main.c:(.text+0x54c): undefined reference to `mcount' This has been corrected in https://reviews.llvm.org/D98881 but the minimum supported clang version is 10.0.1. To avoid build errors and to gain a working function tracer, adjust the name of the mcount symbol for older versions of clang in mount.S and recordmcount.pl. Link: https://github.com/ClangBuiltLinux/linux/issues/1331 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv')
-rw-r--r--arch/riscv/include/asm/ftrace.h14
-rw-r--r--arch/riscv/kernel/mcount.S10
2 files changed, 17 insertions, 7 deletions
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 845002cc2e57..04dad3380041 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -13,9 +13,19 @@
#endif
#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
+/*
+ * Clang prior to 13 had "mcount" instead of "_mcount":
+ * https://reviews.llvm.org/D98881
+ */
+#if defined(CONFIG_CC_IS_GCC) || CONFIG_CLANG_VERSION >= 130000
+#define MCOUNT_NAME _mcount
+#else
+#define MCOUNT_NAME mcount
+#endif
+
#define ARCH_SUPPORTS_FTRACE_OPS 1
#ifndef __ASSEMBLY__
-void _mcount(void);
+void MCOUNT_NAME(void);
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
return addr;
@@ -36,7 +46,7 @@ struct dyn_arch_ftrace {
* both auipc and jalr at the same time.
*/
-#define MCOUNT_ADDR ((unsigned long)_mcount)
+#define MCOUNT_ADDR ((unsigned long)MCOUNT_NAME)
#define JALR_SIGN_MASK (0x00000800)
#define JALR_OFFSET_MASK (0x00000fff)
#define AUIPC_OFFSET_MASK (0xfffff000)
diff --git a/arch/riscv/kernel/mcount.S b/arch/riscv/kernel/mcount.S
index 8a5593ff9ff3..6d462681c9c0 100644
--- a/arch/riscv/kernel/mcount.S
+++ b/arch/riscv/kernel/mcount.S
@@ -47,8 +47,8 @@
ENTRY(ftrace_stub)
#ifdef CONFIG_DYNAMIC_FTRACE
- .global _mcount
- .set _mcount, ftrace_stub
+ .global MCOUNT_NAME
+ .set MCOUNT_NAME, ftrace_stub
#endif
ret
ENDPROC(ftrace_stub)
@@ -78,7 +78,7 @@ ENDPROC(return_to_handler)
#endif
#ifndef CONFIG_DYNAMIC_FTRACE
-ENTRY(_mcount)
+ENTRY(MCOUNT_NAME)
la t4, ftrace_stub
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
la t0, ftrace_graph_return
@@ -124,6 +124,6 @@ do_trace:
jalr t5
RESTORE_ABI_STATE
ret
-ENDPROC(_mcount)
+ENDPROC(MCOUNT_NAME)
#endif
-EXPORT_SYMBOL(_mcount)
+EXPORT_SYMBOL(MCOUNT_NAME)