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From: Song Liu <songliubraving@fb.com>
To: Alexei Starovoitov <ast@kernel.org>
Cc: 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 v3 bpf-next 02/18] bpf: Add bpf_arch_text_poke() helper
Date: Fri, 8 Nov 2019 06:56:07 +0000	[thread overview]
Message-ID: <201D1F23-B4D5-4EB4-8450-128C6E2C1971@fb.com> (raw)
In-Reply-To: <20191108064039.2041889-3-ast@kernel.org>



> On Nov 7, 2019, at 10:40 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>

Acked-by: Song Liu <songliubraving@fb.com>


> ---
> 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..bb8467fd6715 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[X86_CALL_SIZE] = {};
> +	u8 new_insn[X86_CALL_SIZE] = {};
> +	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 (new_addr) {
> +		prog = new_insn;
> +		ret = emit_call(&prog, new_addr, (void *)ip);
> +		if (ret)
> +			return ret;
> +	}
> +	ret = -EBUSY;
> +	mutex_lock(&text_mutex);
> +	switch (t) {
> +	case BPF_MOD_NOP_TO_CALL:
> +		if (memcmp(ip, ideal_nops[NOP_ATOMIC5], X86_CALL_SIZE))
> +			goto out;
> +		text_poke(ip, new_insn, X86_CALL_SIZE);
> +		break;
> +	case BPF_MOD_CALL_TO_CALL:
> +		if (memcmp(ip, old_insn, X86_CALL_SIZE))
> +			goto out;
> +		text_poke(ip, new_insn, X86_CALL_SIZE);
> +		break;
> +	case BPF_MOD_CALL_TO_NOP:
> +		if (memcmp(ip, old_insn, X86_CALL_SIZE))
> +			goto out;
> +		text_poke(ip, ideal_nops[NOP_ATOMIC5], X86_CALL_SIZE);
> +		break;
> +	}
> +	ret = 0;
> +out:
> +	mutex_unlock(&text_mutex);
> +	return ret;
> +}
> +
> static bool ex_handler_bpf(const struct exception_table_entry *x,
> 			   struct pt_regs *regs, int trapnr,
> 			   unsigned long error_code, unsigned long fault_addr)
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 7c7f518811a6..8b90db25348a 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1157,4 +1157,12 @@ static inline u32 bpf_xdp_sock_convert_ctx_access(enum bpf_access_type type,
> }
> #endif /* CONFIG_INET */
> 
> +enum bpf_text_poke_type {
> +	BPF_MOD_NOP_TO_CALL,
> +	BPF_MOD_CALL_TO_CALL,
> +	BPF_MOD_CALL_TO_NOP,
> +};
> +int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
> +		       void *addr1, void *addr2);
> +
> #endif /* _LINUX_BPF_H */
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index c1fde0303280..c4bcec1014a9 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -2140,6 +2140,12 @@ int __weak skb_copy_bits(const struct sk_buff *skb, int offset, void *to,
> 	return -EFAULT;
> }
> 
> +int __weak bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
> +			      void *addr1, void *addr2)
> +{
> +	return -ENOTSUPP;
> +}
> +
> DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
> EXPORT_SYMBOL(bpf_stats_enabled_key);
> 
> -- 
> 2.23.0
> 


  reply	other threads:[~2019-11-08  6:56 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-08  6:40 [PATCH v3 bpf-next 00/18] Introduce BPF trampoline Alexei Starovoitov
2019-11-08  6:40 ` [PATCH v3 bpf-next 01/18] bpf: refactor x86 JIT into helpers Alexei Starovoitov
2019-11-08 19:27   ` Andrii Nakryiko
2019-11-08  6:40 ` [PATCH v3 bpf-next 02/18] bpf: Add bpf_arch_text_poke() helper Alexei Starovoitov
2019-11-08  6:56   ` Song Liu [this message]
2019-11-08  8:23   ` Björn Töpel
2019-11-08 14:09     ` Alexei Starovoitov
2019-11-08  9:11   ` Peter Zijlstra
2019-11-08  9:36     ` Peter Zijlstra
2019-11-08 13:41       ` Alexei Starovoitov
2019-11-08 19:32         ` Alexei Starovoitov
2019-11-08 21:36           ` Peter Zijlstra
2019-11-08 21:39             ` David Miller
2019-11-11  8:14               ` Peter Zijlstra
2019-11-11 10:21                 ` Daniel Borkmann
2019-11-11 16:10                 ` Jonathan Corbet
2019-11-08 23:05             ` Alexei Starovoitov
2019-11-10 10:54               ` Thomas Gleixner
2019-11-08  6:40 ` [PATCH v3 bpf-next 03/18] bpf: Introduce BPF trampoline Alexei Starovoitov
2019-11-08  7:04   ` Song Liu
2019-11-08  6:40 ` [PATCH v3 bpf-next 04/18] libbpf: Introduce btf__find_by_name_kind() Alexei Starovoitov
2019-11-08  7:05   ` Song Liu
2019-11-08 19:21   ` Andrii Nakryiko
2019-11-08  6:40 ` [PATCH v3 bpf-next 05/18] libbpf: Add support to attach to fentry/fexit tracing progs Alexei Starovoitov
2019-11-08  7:12   ` Song Liu
2019-11-08 19:44   ` Andrii Nakryiko
2019-11-08  6:40 ` [PATCH v3 bpf-next 06/18] selftest/bpf: Simple test for fentry/fexit Alexei Starovoitov
2019-11-08  6:40 ` [PATCH v3 bpf-next 07/18] bpf: Add kernel test functions for fentry testing Alexei Starovoitov
2019-11-08  6:40 ` [PATCH v3 bpf-next 08/18] selftests/bpf: Add test for BPF trampoline Alexei Starovoitov
2019-11-08  6:40 ` [PATCH v3 bpf-next 09/18] selftests/bpf: Add fexit tests " Alexei Starovoitov
2019-11-08  6:40 ` [PATCH v3 bpf-next 10/18] selftests/bpf: Add combined fentry/fexit test Alexei Starovoitov
2019-11-08  7:14   ` Song Liu
2019-11-08  6:40 ` [PATCH v3 bpf-next 11/18] selftests/bpf: Add stress test for maximum number of progs Alexei Starovoitov
2019-11-08  7:24   ` Song Liu
2019-11-08  6:40 ` [PATCH v3 bpf-next 12/18] bpf: Reserve space for BPF trampoline in BPF programs Alexei Starovoitov
2019-11-08  7:25   ` Song Liu
2019-11-08  6:40 ` [PATCH v3 bpf-next 13/18] bpf: Fix race in btf_resolve_helper_id() Alexei Starovoitov
2019-11-08  7:32   ` Song Liu
2019-11-08 19:58   ` Andrii Nakryiko
2019-11-08  6:40 ` [PATCH v3 bpf-next 14/18] bpf: Compare BTF types of functions arguments with actual types Alexei Starovoitov
2019-11-08 17:28   ` Song Liu
2019-11-08 17:32     ` Song Liu
2019-11-08 17:57       ` Alexei Starovoitov
2019-11-08 17:59         ` Song Liu
2019-11-08 23:46   ` Andrii Nakryiko
2019-11-08  6:40 ` [PATCH v3 bpf-next 15/18] bpf: Support attaching tracing BPF program to other BPF programs Alexei Starovoitov
2019-11-08 18:49   ` Song Liu
2019-11-08 18:59     ` Alexei Starovoitov
2019-11-08 20:17   ` Toke Høiland-Jørgensen
2019-11-08 21:14     ` Alexei Starovoitov
2019-11-08 21:32       ` Toke Høiland-Jørgensen
2019-11-10  7:17   ` Andrii Nakryiko
2019-11-11 23:04     ` Alexei Starovoitov
2019-11-12  4:38       ` Andrii Nakryiko
2019-11-12  4:47         ` Alexei Starovoitov
2019-11-08  6:40 ` [PATCH v3 bpf-next 16/18] libbpf: Add support for attaching BPF programs " Alexei Starovoitov
2019-11-08 18:57   ` Song Liu
2019-11-08 19:13     ` Alexei Starovoitov
2019-11-08 19:14       ` Song Liu
2019-11-10 16:56   ` Andrii Nakryiko
2019-11-08  6:40 ` [PATCH v3 bpf-next 17/18] selftests/bpf: Extend test_pkt_access test Alexei Starovoitov
2019-11-08 19:03   ` Song Liu
2019-11-10 16:58   ` Andrii Nakryiko
2019-11-08  6:40 ` [PATCH v3 bpf-next 18/18] selftests/bpf: Add a test for attaching BPF prog to another BPF prog and subprog Alexei Starovoitov
2019-11-08 19:13   ` Song Liu
2019-11-10 17:04   ` Andrii Nakryiko
2019-11-11 23:07     ` Alexei Starovoitov

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