This is a note to let you know that I've just added the patch titled
riscv: Workaround mcount name prior to clang-13
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
riscv-workaround-mcount-name-prior-to-clang-13.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7bb7ed24fdba87f2da349107f71b95390c34caa6
Author: Nathan Chancellor <nathan@xxxxxxxxxx>
Date: Thu Mar 25 15:38:06 2021 -0700
riscv: Workaround mcount name prior to clang-13
[ Upstream commit 7ce04771503074a7de7f539cc43f5e1b385cb99b ]
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@xxxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 02fbc175142e..693c3839a7df 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -10,9 +10,19 @@
#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;
@@ -33,7 +43,7 @@ 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)
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 857d5b70b1a9..4f84657f55c2 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -395,7 +395,7 @@ if ($arch eq "x86_64") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
} elsif ($arch eq "riscv") {
$function_regex = "^([0-9a-fA-F]+)\\s+<([^.0-9][0-9a-zA-Z_\\.]+)>:";
- $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_mcount\$";
+ $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_?mcount\$";
$type = ".quad";
$alignment = 2;
} elsif ($arch eq "nds32") {
