From: Anders Roxell anders.roxell@linaro.org
commit 8219d31effa7be5dbc7ff915d7970672e028c701 upstream.
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...
Fixes: 350779a29f11 ("powerpc: Handle most loads and stores in instruction emulation code") Cc: stable@vger.kernel.org # v4.14+ 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 Reviewed-by: Segher Boessenkool segher@kernel.crashing.org Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20220224162215.3406642-3-anders.roxell@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/lib/sstep.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -906,7 +906,10 @@ 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" \ @@ -919,7 +922,10 @@ 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" \