riscv: Adjust dependencies of HAVE_DYNAMIC_FTRACE selection

When building allmodconfig with clang and its integrated assembler and
linking with a version of GNU ld prior to 2.36, the following link error
occurs:

  riscv64-linux-gnu-ld: .init.data has both ordered [`__patchable_function_entries' in init/main.o] and unordered [`.init_array.0' in kernel/trace/trace_benchmark.o] sections
  riscv64-linux-gnu-ld: final link failed: bad value

This is the same error addressed by commit 45bd8951806e ("arm64: Improve
HAVE_DYNAMIC_FTRACE_WITH_REGS selection for clang") for arm64. See that
changelog for a full description of why this error occurs with this
combination of tools.

In a similar manner as that change, restrict the
CONFIG_HAVE_DYNAMIC_FTRACE selection to combinations of tools known to
work so that there are no errors.

Link: https://github.com/ClangBuiltLinux/linux/issues/1817
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230404-riscv-dynamic-ftrace-checks-clang-v1-1-0ce296b7d423@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 5c88ac4..7f4c558 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -142,12 +142,23 @@ config RISCV
        select TRACE_IRQFLAGS_SUPPORT
        select UACCESS_MEMCPY if !MMU
        select ZONE_DMA32 if 64BIT
-       select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && $(cc-option,-fpatchable-function-entry=8)
+       select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE)
        select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
        select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
        select HAVE_FUNCTION_GRAPH_TRACER
        select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION
 
+config CLANG_SUPPORTS_DYNAMIC_FTRACE
+       def_bool CC_IS_CLANG
+       # https://github.com/llvm/llvm-project/commit/6ab8927931851bb42b2c93a00801dc499d7d9b1e
+       depends on CLANG_VERSION >= 130000
+       # https://github.com/ClangBuiltLinux/linux/issues/1817
+       depends on AS_IS_GNU || (AS_IS_LLVM && (LD_IS_LLD || LD_VERSION >= 23600))
+
+config GCC_SUPPORTS_DYNAMIC_FTRACE
+       def_bool CC_IS_GCC
+       depends on $(cc-option,-fpatchable-function-entry=8)
+
 config ARCH_MMAP_RND_BITS_MIN
        default 18 if 64BIT
        default 8