• Thomas Richter's avatar
    perf trace: Use the right bpf_probe_read(_str) variant for reading user data · 5069211e
    Thomas Richter authored
    Perf test case 111 Check open filename arg using perf trace + vfs_getname
    fails on s390. This is caused by a failing function
    bpf_probe_read() in file util/bpf_skel/augmented_raw_syscalls.bpf.c.
    
    The root cause is the lookup by address. Function bpf_probe_read()
    is used. This function works only for architectures
    with ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
    
    On s390 is not possible to determine from the address to which
    address space the address belongs to (user or kernel space).
    
    Replace bpf_probe_read() by bpf_probe_read_kernel()
    and bpf_probe_read_str() by bpf_probe_read_user_str() to
    explicity specify the address space the address refers to.
    
    Output before:
     # ./perf trace -eopen,openat -- touch /tmp/111
     libbpf: prog 'sys_enter': BPF program load failed: Invalid argument
     libbpf: prog 'sys_enter': -- BEGIN PROG LOAD LOG --
     reg type unsupported for arg#0 function sys_enter#75
     0: R1=ctx(off=0,imm=0) R10=fp0
     ; int sys_enter(struct syscall_enter_args *args)
     0: (bf) r6 = r1           ; R1=ctx(off=0,imm=0) R6_w=ctx(off=0,imm=0)
     ; return bpf_get_current_pid_tgid();
     1: (85) call bpf_get_current_pid_tgid#14      ; R0_w=scalar()
     2: (63) *(u32 *)(r10 -8) = r0 ; R0_w=scalar() R10=fp0 fp-8=????mmmm
     3: (bf) r2 = r10              ; R2_w=fp0 R10=fp0
     ;
     .....
     lines deleted here
     .....
     23: (bf) r3 = r6              ; R3_w=ctx(off=0,imm=0) R6=ctx(off=0,imm=0)
     24: (85) call bpf_probe_read#4
     unknown func bpf_probe_read#4
     processed 23 insns (limit 1000000) max_states_per_insn 0 \
    	 total_states 2 peak_states 2 mark_read 2
     -- END PROG LOAD LOG --
     libbpf: prog 'sys_enter': failed to load: -22
     libbpf: failed to load object 'augmented_raw_syscalls_bpf'
     libbpf: failed to load BPF skeleton 'augmented_raw_syscalls_bpf': -22
     ....
    
    Output after:
     # ./perf test -Fv 111
     111: Check open filename arg using perf trace + vfs_getname          :
     --- start ---
         1.085 ( 0.011 ms): touch/320753 openat(dfd: CWD, filename: \
    	"/tmp/temporary_file.SWH85", \
    	flags: CREAT|NOCTTY|NONBLOCK|WRONLY, mode: IRUGO|IWUGO) = 3
     ---- end ----
     Check open filename arg using perf trace + vfs_getname: Ok
     #
    
    Test with the sleep command shows:
    Output before:
     # ./perf trace -e *sleep sleep 1.234567890
         0.000 (1234.681 ms): sleep/63114 clock_nanosleep(rqtp: \
             { .tv_sec: 0, .tv_nsec: 0 }, rmtp: 0x3ffe0979720) = 0
     #
    
    Output after:
     # ./perf trace -e *sleep sleep 1.234567890
         0.000 (1234.686 ms): sleep/64277 clock_nanosleep(rqtp: \
             { .tv_sec: 1, .tv_nsec: 234567890 }, rmtp: 0x3fff3df9ea0) = 0
     #
    
    Fixes: 14e4b9f4 ("perf trace: Raw augmented syscalls fix libbpf 1.0+ compatibility")
    Signed-off-by: default avatarThomas Richter <tmricht@linux.ibm.com>
    Co-developed-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    Acked-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
    Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Ian Rogers <irogers@google.com>
    Cc: gor@linux.ibm.com
    Cc: hca@linux.ibm.com
    Cc: sumanthk@linux.ibm.com
    Cc: svens@linux.ibm.com
    Link: https://lore.kernel.org/r/20231019082642.3286650-1-tmricht@linux.ibm.comSigned-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
    5069211e
augmented_raw_syscalls.bpf.c 12.5 KB