Building tinyconfig with gcc (Debian 11.2.0-16) and assembler (Debian 2.37.90.20220207) the following build error shows up:
{standard input}: Assembler messages: {standard input}:10576: Error: unrecognized opcode: `stbcx.' {standard input}:10680: Error: unrecognized opcode: `lharx' {standard input}:10694: Error: unrecognized opcode: `lbarx'
Rework to add assembler directives [1] around the instruction. The problem with this might be that we can trick a power6 into single-stepping through an stbcx. for instance, and it will execute that in kernel mode.
[1] https://sourceware.org/binutils/docs/as/PowerPC_002dPseudo.html#PowerPC_002d...
Cc: stable@vger.kernel.org Co-developed-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Anders Roxell anders.roxell@linaro.org --- arch/powerpc/lib/sstep.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index d2d29243fa6d..b9f43bbdd55a 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -1097,7 +1097,10 @@ NOKPROBE_SYMBOL(emulate_dcbz);
#define __put_user_asmx(x, addr, err, op, cr) \ __asm__ __volatile__( \ + ".machine "push"\n" \ + ".machine "power8"\n" \ "1: " op " %2,0,%3\n" \ + ".machine "pop"\n" \ " mfcr %1\n" \ "2:\n" \ ".section .fixup,"ax"\n" \ @@ -1110,7 +1113,10 @@ NOKPROBE_SYMBOL(emulate_dcbz);
#define __get_user_asmx(x, addr, err, op) \ __asm__ __volatile__( \ + ".machine "push"\n" \ + ".machine "power8"\n" \ "1: "op" %1,0,%2\n" \ + ".machine "pop"\n" \ "2:\n" \ ".section .fixup,"ax"\n" \ "3: li %0,%3\n" \