From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Song Liu <songliubraving@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
David Miller <davem@davemloft.net>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
"x86@kernel.org" <x86@kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH v2 bpf-next 02/17] bpf: Add bpf_arch_text_poke() helper
Date: Thu, 7 Nov 2019 09:50:39 -0800 [thread overview]
Message-ID: <CAADnVQJsnVmTNxj1QbEbHCsvyvL348R08cZ6ChZK8EGnpc2BfQ@mail.gmail.com> (raw)
In-Reply-To: <EE50EB7D-8FB0-4D37-A3F1-3439981A6141@fb.com>
On Thu, Nov 7, 2019 at 9:20 AM Song Liu <songliubraving@fb.com> wrote:
>
>
>
> > On Nov 6, 2019, at 9:46 PM, Alexei Starovoitov <ast@kernel.org> wrote:
> >
> > Add bpf_arch_text_poke() helper that is used by BPF trampoline logic to patch
> > nops/calls in kernel text into calls into BPF trampoline and to patch
> > calls/nops inside BPF programs too.
> >
> > Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> > ---
> > arch/x86/net/bpf_jit_comp.c | 51 +++++++++++++++++++++++++++++++++++++
> > include/linux/bpf.h | 8 ++++++
> > kernel/bpf/core.c | 6 +++++
> > 3 files changed, 65 insertions(+)
> >
> > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
> > index 0399b1f83c23..8631d3bd637f 100644
> > --- a/arch/x86/net/bpf_jit_comp.c
> > +++ b/arch/x86/net/bpf_jit_comp.c
> > @@ -9,9 +9,11 @@
> > #include <linux/filter.h>
> > #include <linux/if_vlan.h>
> > #include <linux/bpf.h>
> > +#include <linux/memory.h>
> > #include <asm/extable.h>
> > #include <asm/set_memory.h>
> > #include <asm/nospec-branch.h>
> > +#include <asm/text-patching.h>
> >
> > static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
> > {
> > @@ -487,6 +489,55 @@ static int emit_call(u8 **pprog, void *func, void *ip)
> > return 0;
> > }
> >
> > +int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
> > + void *old_addr, void *new_addr)
> > +{
> > + u8 old_insn[NOP_ATOMIC5] = {};
> > + u8 new_insn[NOP_ATOMIC5] = {};
> > + u8 *prog;
> > + int ret;
> > +
> > + if (!is_kernel_text((long)ip))
> > + /* BPF trampoline in modules is not supported */
> > + return -EINVAL;
> > +
> > + if (old_addr) {
> > + prog = old_insn;
> > + ret = emit_call(&prog, old_addr, (void *)ip);
> > + if (ret)
> > + return ret;
> > + }
> > + if (old_addr) {
> ^ should be new_addr?
> > + prog = new_insn;
> > + ret = emit_call(&prog, old_addr, (void *)ip);
> ^^^ and here?
> > + if (ret)
> > + return ret;
> > + }
> > + ret = -EBUSY;
> > + mutex_lock(&text_mutex);
> > + switch (t) {
> > + case BPF_MOD_NOP_TO_CALL:
> > + if (memcmp(ip, ideal_nops, 5))
>
> Maybe use X86_CALL_SIZE instead of 5? And the five more "5" below?
ohh. yes. of course. I had it fixed.
NOP_ATOMIC5 above is incorrect as well. I had it fixed too.
Looks like I've lost another squash commit last night.
Sorry about that.
next prev parent reply other threads:[~2019-11-07 17:50 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-07 5:46 [PATCH v2 bpf-next 00/17] Introduce BPF trampoline Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 01/17] bpf: refactor x86 JIT into helpers Alexei Starovoitov
2019-11-07 17:05 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 02/17] bpf: Add bpf_arch_text_poke() helper Alexei Starovoitov
2019-11-07 17:20 ` Song Liu
2019-11-07 17:50 ` Alexei Starovoitov [this message]
2019-11-07 17:54 ` Alexei Starovoitov
2019-11-07 18:04 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 03/17] bpf: Introduce BPF trampoline Alexei Starovoitov
2019-11-07 22:37 ` Song Liu
2019-11-07 22:55 ` Alexei Starovoitov
2019-11-07 23:07 ` Song Liu
2019-11-07 23:09 ` Alexei Starovoitov
2019-11-07 23:16 ` Song Liu
2019-11-08 0:09 ` Alexei Starovoitov
2019-11-08 1:10 ` Song Liu
2019-11-08 3:11 ` Alexei Starovoitov
2019-11-08 4:06 ` Song Liu
2019-11-08 4:08 ` Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 04/17] libbpf: Add support to attach to fentry/fexit tracing progs Alexei Starovoitov
2019-11-07 22:51 ` Song Liu
2019-11-07 23:07 ` Alexei Starovoitov
2019-11-07 23:13 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 05/17] selftest/bpf: Simple test for fentry/fexit Alexei Starovoitov
2019-11-07 23:22 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 06/17] bpf: Add kernel test functions for fentry testing Alexei Starovoitov
2019-11-07 23:28 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 07/17] selftests/bpf: Add test for BPF trampoline Alexei Starovoitov
2019-11-08 1:17 ` Song Liu
2019-11-08 2:33 ` Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 08/17] selftests/bpf: Add fexit tests " Alexei Starovoitov
2019-11-08 1:22 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 09/17] selftests/bpf: Add combined fentry/fexit test Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 10/17] selftests/bpf: Add stress test for maximum number of progs Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 11/17] bpf: Reserver space for BPF trampoline in BPF programs Alexei Starovoitov
2019-11-08 5:03 ` Andrii Nakryiko
2019-11-07 5:46 ` [PATCH v2 bpf-next 12/17] bpf: Fix race in btf_resolve_helper_id() Alexei Starovoitov
2019-11-08 5:13 ` Andrii Nakryiko
2019-11-08 5:31 ` Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 13/17] bpf: Compare BTF types of functions arguments with actual types Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 14/17] bpf: Support attaching tracing BPF program to other BPF programs Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 15/17] selftests/bpf: Extend test_pkt_access test Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 16/17] libbpf: Add support for attaching BPF programs to other BPF programs Alexei Starovoitov
2019-11-07 14:33 ` Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 17/17] selftests/bpf: Add a test for attaching BPF prog to another BPF prog and subprog Alexei Starovoitov
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