From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Mon, 16 Nov 2015 11:39:12 +0000 Subject: [PATCH] bpf, arm64: start flushing icache range from header In-Reply-To: <41c4a481eb665a492c3b2df16af219b1250224a0.1447446460.git.daniel@iogearbox.net> References: <41c4a481eb665a492c3b2df16af219b1250224a0.1447446460.git.daniel@iogearbox.net> Message-ID: <20151116113912.GB20696@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sat, Nov 14, 2015 at 01:16:18AM +0100, Daniel Borkmann wrote: > While recently going over ARM64's BPF code, I noticed that the icache > range we're flushing should start at header already and not at ctx.image. > > Reason is that after b569c1c622c5 ("net: bpf: arm64: address randomize > and write protect JIT code"), we also want to make sure to flush the > random-sized trap in front of the start of the actual program (analogous > to x86). No operational differences from user side. > > Signed-off-by: Daniel Borkmann > Acked-by: Zi Shen Lim > Cc: Alexei Starovoitov > --- > ( As arm64 jit fixes seem to go via arm64 tree, sending them here. ) > > arch/arm64/net/bpf_jit_comp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index a44e529..ee06570 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -740,7 +740,7 @@ void bpf_int_jit_compile(struct bpf_prog *prog) > if (bpf_jit_enable > 1) > bpf_jit_dump(prog->len, image_size, 2, ctx.image); > > - bpf_flush_icache(ctx.image, ctx.image + ctx.idx); > + bpf_flush_icache(header, ctx.image + ctx.idx); As far as I can see, ctx.idx doesn't take into account the size of the header, given we zero it after bpf_jit_binary_alloc, and increment it for each instruction. So won't this prevent us from flushing the end of the image? Or did I miss something? Mark.