[PATCH fixes] riscv: Fix CONFIG_AS_HAS_INSN for new .insn usage

[Nathan Chancellor]

After commit 44aa25c000b4 ("riscv: asm: use .insn for making custom
instructions"), builds using LLVM older that 19 or binutils older than
2.38 fail with:

  arch/riscv/include/asm/vdso/processor.h: Assembler messages:
  arch/riscv/include/asm/vdso/processor.h:27: Error: unrecognized opcode `0x100000f'
  arch/riscv/include/asm/vdso/processor.h:27: Error: unrecognized opcode `0x100000f'
  arch/riscv/include/asm/vdso/processor.h:27: Error: unrecognized opcode `0x100000f'
  arch/riscv/include/asm/vdso/processor.h:27: Error: unrecognized opcode `0x100000f'
  make[4]: *** [scripts/Makefile.build:287: arch/riscv/kernel/vdso/vgettimeofday.o] Error 1

  In file included from <built-in>:4:
  In file included from lib/vdso/gettimeofday.c:6:
  In file included from include/vdso/datapage.h:21:
  In file included from include/vdso/processor.h:10:
  arch/riscv/include/asm/vdso/processor.h:23:2: error: expected instruction format
     23 |         ALT_RISCV_PAUSE();
        |         ^
  arch/riscv/include/asm/errata_list.h:47:3: note: expanded from macro 'ALT_RISCV_PAUSE'
     47 |                 RISCV_PAUSE, /* Original RISC‑V pause insn */ \
        |                 ^
  arch/riscv/include/asm/insn-def.h:259:21: note: expanded from macro 'RISCV_PAUSE'
    259 | #define RISCV_PAUSE     ASM_INSN_I("0x100000f")
        |                         ^
  arch/riscv/include/asm/asm.h:16:26: note: expanded from macro 'ASM_INSN_I'
     16 | #define ASM_INSN_I(__x) ".insn " __x
        |                          ^
  <inline asm>:5:7: note: instantiated into assembly here
      5 | .insn 0x100000f
        |       ^

binutils gained support for '.insn <value>' in 2.38 [1] and LLVM gained
support in 19 [2]. Adjust the test for CONFIG_AS_HAS_INSN to ensure that
all versions of .insn are supported before being used.

Fixes: 44aa25c000b4 ("riscv: asm: use .insn for making custom instructions")
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=a262b82fdbf4cda3b0648b1adc32245ca3f78b7a [1]
Link: https://github.com/llvm/llvm-project/commit/2a086dce691e3cc34a2fc27f4fb255bb2cbbfac9 [2]
Suggested-by: Andrew Jones <ajones at ventanamicro.com>
Signed-off-by: Nathan Chancellor <nathan at kernel.org>
---
 arch/riscv/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 22cda9c452d2..fadec20b87a8 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -367,7 +367,7 @@ config RISCV_NONSTANDARD_CACHE_OPS
 	  systems to handle cache management.
 
 config AS_HAS_INSN
-	def_bool $(as-instr,.insn r 51$(comma) 0$(comma) 0$(comma) t0$(comma) t0$(comma) zero)
+	def_bool $(as-instr,.insn 0x100000f)
 
 config AS_HAS_OPTION_ARCH
 	# https://github.com/llvm/llvm-project/commit/9e8ed3403c191ab9c4903e8eeb8f732ff8a43cb4

---
base-commit: a882126c42fc53275ac91969d460d939191db7b0
change-id: 20251107-riscv-fix-new-insn-usage-2261377c2d38

Best regards,
--  
Nathan Chancellor <nathan at kernel.org>