From fef071be57dc43679a32d5b0e6ee176d6f12e9f2 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 14 Oct 2021 13:44:24 +1100 Subject: powerpc/dcr: Use cmplwi instead of 3-argument cmpli MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In dcr-low.S we use cmpli with three arguments, instead of four arguments as defined in the ISA: cmpli cr0,r3,1024 This appears to be a PPC440-ism, looking at the "PPC440x5 CPU Core User’s Manual" it shows cmpli having no L field, but implied to be 0 due to the core being 32-bit. It mentions that the ISA defines four arguments and recommends using cmplwi. It also corresponds to the old POWER instruction set, which had no L field there, a reserved bit instead. dcr-low.S is only built 32-bit, because it is only built when DCR_NATIVE=y, which is only selected by 40x and 44x. Looking at the generated code (with gcc/gas) we see cmplwi as expected. Although gas is happy with the 3-argument version when building for 32-bit, the LLVM assembler is not and errors out with: arch/powerpc/sysdev/dcr-low.S:27:10: error: invalid operand for instruction cmpli 0,%r3,1024; ... ^ Switch to the cmplwi extended opcode, which avoids any confusion when reading the ISA, fixes the issue with the LLVM assembler, and also means the code could be built 64-bit in future (though that's very unlikely). Reported-by: Nick Desaulniers Reviewed-by: Nick Desaulniers Signed-off-by: Michael Ellerman BugLink: https://github.com/ClangBuiltLinux/linux/issues/1419 Link: https://lore.kernel.org/r/20211014024424.528848-1-mpe@ellerman.id.au --- arch/powerpc/sysdev/dcr-low.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/powerpc') diff --git a/arch/powerpc/sysdev/dcr-low.S b/arch/powerpc/sysdev/dcr-low.S index efeeb1b885a1..329b9c4ae542 100644 --- a/arch/powerpc/sysdev/dcr-low.S +++ b/arch/powerpc/sysdev/dcr-low.S @@ -11,7 +11,7 @@ #include #define DCR_ACCESS_PROLOG(table) \ - cmpli cr0,r3,1024; \ + cmplwi cr0,r3,1024; \ rlwinm r3,r3,4,18,27; \ lis r5,table@h; \ ori r5,r5,table@l; \ -- cgit v1.2.3