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Jesper wanted to see offsets at callq sites when doing some performance
investigation related to retpolines, so save him some time by providing
a 'O' hotkey to allow showing offsets from function start at call
instructions or in all instructions, just go on pressing 'O' till the
offsets you need appear.
Example:
Starts with:
Samples: 64 of event 'cycles:ppp', 100000 Hz, Event count (approx.): 318963
ixgbe_read_reg /proc/kcore
Percent│ ↑ je 2a
│ ┌──cmp $0xffffffff,%r13d
│ ├──je d0
│ │ mov $0x53e3,%edi
│ │→ callq __const_udelay
│ │ sub $0x1,%r15d
│ │↑ jne 83
│ │ mov 0x8(%rbp),%rax
│ │ testb $0x20,0x1799(%rax)
│ │↑ je 2a
│ │ mov 0x200(%rax),%rdi
│ │ mov %r13d,%edx
│ │ mov $0xffffffffc02595d8,%rsi
│ │→ callq netdev_warn
│ │↑ jmpq 2a
│d0:└─→mov 0x8(%rbp),%rsi
│ mov %rbp,%rdi
│ mov %eax,0x4(%rsp)
│ → callq ixgbe_remove_adapter.isra.77
│ mov 0x4(%rsp),%eax
Press 'h' for help on key bindings
============================================================================
Pess 'O':
Samples: 64 of event 'cycles:ppp', 100000 Hz, Event count (approx.): 318963
ixgbe_read_reg /proc/kcore
Percent│ ↑ je 2a
│ ┌──cmp $0xffffffff,%r13d
│ ├──je d0
│ │ mov $0x53e3,%edi
│99:│→ callq __const_udelay
│ │ sub $0x1,%r15d
│ │↑ jne 83
│ │ mov 0x8(%rbp),%rax
│ │ testb $0x20,0x1799(%rax)
│ │↑ je 2a
│ │ mov 0x200(%rax),%rdi
│ │ mov %r13d,%edx
│ │ mov $0xffffffffc02595d8,%rsi
│c6:│→ callq netdev_warn
│ │↑ jmpq 2a
│d0:└─→mov 0x8(%rbp),%rsi
│ mov %rbp,%rdi
│ mov %eax,0x4(%rsp)
│db: → callq ixgbe_remove_adapter.isra.77
│ mov 0x4(%rsp),%eax
Press 'h' for help on key bindings
============================================================================
Press 'O' again:
Samples: 64 of event 'cycles:ppp', 100000 Hz, Event count (approx.): 318963
ixgbe_read_reg /proc/kcore
Percent│8c: ↑ je 2a
│8e:┌──cmp $0xffffffff,%r13d
│92:├──je d0
│94:│ mov $0x53e3,%edi
│99:│→ callq __const_udelay
│9e:│ sub $0x1,%r15d
│a2:│↑ jne 83
│a4:│ mov 0x8(%rbp),%rax
│a8:│ testb $0x20,0x1799(%rax)
│af:│↑ je 2a
│b5:│ mov 0x200(%rax),%rdi
│bc:│ mov %r13d,%edx
│bf:│ mov $0xffffffffc02595d8,%rsi
│c6:│→ callq netdev_warn
│cb:│↑ jmpq 2a
│d0:└─→mov 0x8(%rbp),%rsi
│d4: mov %rbp,%rdi
│d7: mov %eax,0x4(%rsp)
│db: → callq ixgbe_remove_adapter.isra.77
│e0: mov 0x4(%rsp),%eax
Press 'h' for help on key bindings
============================================================================
Press 'O' again and it will show just jump target offsets.
Suggested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Liška <mliska@suse.cz>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-upp6pfdetwlsx18ec2uf1od4@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.