On 11/7/19 9:50 AM, Alexei Starovoitov wrote:
> On Thu, Nov 7, 2019 at 9:20 AM Song Liu <songliubraving@xxxxxx> wrote:
>>
>>
>>
>>> On Nov 6, 2019, at 9:46 PM, Alexei Starovoitov <ast@xxxxxxxxxx> 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@xxxxxxxxxx>
>>> ---
>>> 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.
Argh. Now I see what happened.
I squashed it into patch 3 instead of patch 2. sorry.
