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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 62ea4831-a5de-4108-f7f8-08d763a6c87e X-MS-Exchange-CrossTenant-originalarrivaltime: 07 Nov 2019 17:20:27.4530 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: eln14gJzr3bdhGHoXqNm184d17nYHnxDy4CLXT++GE8r0MzrGzAZlsVMpEBUXF5HMiZMKgQnzF6zQHW2YvOhUA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1808 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-11-07_05:2019-11-07,2019-11-07 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 lowpriorityscore=0 clxscore=1015 malwarescore=0 mlxlogscore=999 suspectscore=0 adultscore=0 mlxscore=0 bulkscore=0 phishscore=0 priorityscore=1501 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1911070162 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org > On Nov 6, 2019, at 9:46 PM, Alexei Starovoitov wrote: >=20 > Add bpf_arch_text_poke() helper that is used by BPF trampoline logic to p= atch > nops/calls in kernel text into calls into BPF trampoline and to patch > calls/nops inside BPF programs too. >=20 > Signed-off-by: Alexei Starovoitov > --- > arch/x86/net/bpf_jit_comp.c | 51 +++++++++++++++++++++++++++++++++++++ > include/linux/bpf.h | 8 ++++++ > kernel/bpf/core.c | 6 +++++ > 3 files changed, 65 insertions(+) >=20 > 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 > #include > #include > +#include > #include > #include > #include > +#include >=20 > static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len) > { > @@ -487,6 +489,55 @@ static int emit_call(u8 **pprog, void *func, void *i= p) > return 0; > } >=20 > +int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, > + void *old_addr, void *new_addr) > +{ > + u8 old_insn[NOP_ATOMIC5] =3D {}; > + u8 new_insn[NOP_ATOMIC5] =3D {}; > + u8 *prog; > + int ret; > + > + if (!is_kernel_text((long)ip)) > + /* BPF trampoline in modules is not supported */ > + return -EINVAL; > + > + if (old_addr) { > + prog =3D old_insn; > + ret =3D emit_call(&prog, old_addr, (void *)ip); > + if (ret) > + return ret; > + } > + if (old_addr) { ^ should be new_addr? > + prog =3D new_insn; > + ret =3D emit_call(&prog, old_addr, (void *)ip); ^^^ and here?=20 > + if (ret) > + return ret; > + } > + ret =3D -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? > + goto out; > + text_poke(ip, new_insn, 5); > + break; > + case BPF_MOD_CALL_TO_CALL: > + if (memcmp(ip, old_insn, 5)) > + goto out; > + text_poke(ip, new_insn, 5); > + break; > + case BPF_MOD_CALL_TO_NOP: > + if (memcmp(ip, old_insn, 5)) > + goto out; > + text_poke(ip, ideal_nops, 5); > + break; > + } > + ret =3D 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 */ >=20 > +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 97e37d82a1cc..856564e97943 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; > } >=20 > +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); >=20 > --=20 > 2.23.0 >=20