powerpc32/bpf: Fix codegen for bpf-to-bpf calls

commit fab07611fb2e6a15fac05c4583045ca5582fd826 upstream.

Pad instructions emitted for BPF_CALL so that the number of instructions
generated does not change for different function addresses. This is
especially important for calls to other bpf functions, whose address
will only be known during extra pass.

Fixes: 51c66ad849a703 ("powerpc/bpf: Implement extended BPF on PPC32")
Cc: stable@vger.kernel.org # v5.13+
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/52d8fe51f7620a6f27f377791564d79d75463576.1641468127.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index 0da31d41d4131068fa5543cbe0dbdd30051f13fb..f2c28c9268ef64ea4274a97686791710649b364c 100644 (file)
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -191,6 +191,9 @@ void bpf_jit_emit_func_call_rel(u32 *image, struct codegen_context *ctx, u64 fun
 
        if (image && rel < 0x2000000 && rel >= -0x2000000) {
                PPC_BL_ABS(func);
+               EMIT(PPC_RAW_NOP());
+               EMIT(PPC_RAW_NOP());
+               EMIT(PPC_RAW_NOP());
        } else {
                /* Load function address into r0 */
                EMIT(PPC_RAW_LIS(_R0, IMM_H(func)));