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Tue, 07 Jul 2026 23:03:20 -0700 (PDT) From: Nils Juenemann To: rjethwani@everpuredata.com Cc: borisp@nvidia.com, davem@davemloft.net, edumazet@google.com, john.fastabend@gmail.com, kuba@kernel.org, leon@kernel.org, mbloch@nvidia.com, netdev@vger.kernel.org, nils.juenemann@gmail.com, pabeni@redhat.com, saeedm@nvidia.com, sd@queasysnail.net, tariqt@nvidia.com Subject: Re: [PATCH net-next v14 0/9] tls: Add TLS 1.3 hardware offload support Date: Wed, 8 Jul 2026 08:03:19 +0200 Message-ID: <20260708060319.68063-1-nils.juenemann@gmail.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Tue, Jul 7, 2026 at 5:31 PM Rishikesh Jethwani wrote: > > Could you post the disassembly [...] count how many distinct loads of > sk+0x4f8 the compiler emitted in that region. objdump of mlx5e_ktls_handle_rx_skb, CQE_TLS_OFFLOAD_RESYNC branch (+0x63) through RIP+0x10a; bytes match the oops Code around the fault: 11bd03: 48 83 82 90 01 00 00 addq $0x1,0x190(%rdx) 11bd0a: 01 11bd0b: 48 8b b6 d0 00 00 00 mov 0xd0(%rsi),%rsi 11bd12: 49 89 fc mov %rdi,%r12 11bd15: 4c 8b b7 00 01 00 00 mov 0x100(%rdi),%r14 11bd1c: 0f b7 46 0c movzwl 0xc(%rsi),%eax 11bd20: 4d 8b be 08 01 00 00 mov 0x108(%r14),%r15 11bd27: 66 3d 81 00 cmp $0x81,%ax 11bd2b: 0f 84 a4 01 00 00 je 11bed5 11bd31: 66 3d 88 a8 cmp $0xa888,%ax 11bd35: 0f 84 9a 01 00 00 je 11bed5 11bd3b: 0f b7 43 78 movzwl 0x78(%rbx),%eax 11bd3f: 49 89 c5 mov %rax,%r13 11bd42: 48 01 c6 add %rax,%rsi 11bd45: 45 8b 8e e0 00 00 00 mov 0xe0(%r14),%r9d 11bd4c: 0f b6 06 movzbl (%rsi),%eax 11bd4f: 83 e0 f0 and $0xfffffff0,%eax 11bd52: 3c 40 cmp $0x40,%al 11bd54: 0f 84 a8 01 00 00 je 11bf02 11bd5a: 44 0f b7 46 2a movzwl 0x2a(%rsi),%r8d 11bd5f: 41 8d 45 28 lea 0x28(%r13),%eax 11bd63: 0f b7 56 28 movzwl 0x28(%rsi),%edx 11bd67: 4c 89 ff mov %r15,%rdi 11bd6a: 89 45 d4 mov %eax,-0x2c(%rbp) 11bd6d: 48 8d 4e 18 lea 0x18(%rsi),%rcx 11bd71: 4c 8d 76 28 lea 0x28(%rsi),%r14 11bd75: 48 83 c6 08 add $0x8,%rsi 11bd79: 6a 00 push $0x0 11bd7b: 66 41 c1 c0 08 rol $0x8,%r8w 11bd80: 45 0f b7 c0 movzwl %r8w,%r8d 11bd84: e8 00 00 00 00 call 11bd89 11bd89: 49 89 c7 mov %rax,%r15 11bd8c: 58 pop %rax 11bd8d: 4d 85 ff test %r15,%r15 11bd90: 0f 84 4a ff ff ff je 11bce0 11bd96: 41 0f b6 47 12 movzbl 0x12(%r15),%eax 11bd9b: 3c 06 cmp $0x6,%al 11bd9d: 0f 84 cc 00 00 00 je 11be6f 11bda3: 49 8b 87 f8 04 00 00 mov 0x4f8(%r15),%rax 11bdaa: 48 8b 40 30 mov 0x30(%rax),%rax One load of sk+0x4f8 in this range, at 11bda3 (the fault). r15 only becomes sk at 11bd89 (mov %rax,%r15), so there is no sk+0x4f8 dereference before 11bda3 in this range. The only other sk+0x4f8 load in the function is 11be20, after the fault and not reached. So my earlier "two independent loads, second reading NULL" was wrong. Thanks, Nils