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895891dad7
When checking the match variable at the target instruction, it might not have any information if it's a first write to a stack slot. In this case it could spill a register value into the stack so the type info is in the source operand. But currently it's hard to get the operand from the checking function. Let's process the instruction and retry to get the type info from the stack if there's no information already. This is an example of __tcp_transmit_skb(). The instructions are <__tcp_transmit_skb>: 0: nopl 0x0(%rax, %rax, 1) 5: push %rbp 6: mov %rsp, %rbp 9: push %r15 b: push %r14 d: push %r13 f: push %r12 11: push %rbx 12: sub $0x98, %rsp 19: mov %r8d, -0xa8(%rbp) ... It cannot find any variable at -0xa8(%rbp) at this point. ----------------------------------------------------------- find data type for -0xa8(reg6) at __tcp_transmit_skb+0x19 CU for net/ipv4/tcp_output.c (die:0x817f543) frame base: cfa=0 fbreg=6 scope: [1/1] (die:81aac3e) bb: [0 - 19] var [0] -0x98(stack) type='struct tcp_out_options' size=0x28 (die:0x81af3df) var [5] reg8 type='unsigned int' size=0x4 (die:0x8180ed6) var [5] reg2 type='unsigned int' size=0x4 (die:0x8180ed6) var [5] reg1 type='int' size=0x4 (die:0x818059e) var [5] reg4 type='struct sk_buff*' size=0x8 (die:0x8181360) var [5] reg5 type='struct sock*' size=0x8 (die:0x8181a0c) chk [19] reg6 offset=-0xa8 ok=0 kind=0 fbreg : no type information no type information And it was able to find the type after processing the 'mov' instruction. ----------------------------------------------------------- find data type for -0xa8(reg6) at __tcp_transmit_skb+0x19 CU for net/ipv4/tcp_output.c (die:0x817f543) frame base: cfa=0 fbreg=6 scope: [1/1] (die:81aac3e) bb: [0 - 19] var [0] -0x98(stack) type='struct tcp_out_options' size=0x28 (die:0x81af3df) var [5] reg8 type='unsigned int' size=0x4 (die:0x8180ed6) var [5] reg2 type='unsigned int' size=0x4 (die:0x8180ed6) var [5] reg1 type='int' size=0x4 (die:0x818059e) var [5] reg4 type='struct sk_buff*' size=0x8 (die:0x8181360) var [5] reg5 type='struct sock*' size=0x8 (die:0x8181a0c) chk [19] reg6 offset=-0xa8 ok=0 kind=0 fbreg : retry <<<--- here mov [19] reg8 -> -0xa8(stack) type='unsigned int' size=0x4 (die:0x8180ed6) chk [19] reg6 offset=-0xa8 ok=0 kind=0 fbreg : Good! found by insn track: -0xa8(reg6) type-offset=0 final result: type='unsigned int' size=0x4 (die:0x8180ed6) Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20240821232628.353177-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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