Thread (30 messages) 30 messages, 7 authors, 2019-12-03

Re: [PATCH] libbpf: Use PRIu64 for sym->st_value to fix build on 32-bit arches

From: Alexei Starovoitov <hidden>
Date: 2019-11-27 19:33:16
Also in: bpf, linux-perf-users, lkml

On Wed, Nov 27, 2019 at 5:45 AM Arnaldo Carvalho de Melo
[off-list ref] wrote:
quoted hunk ↗ jump to hunk
Another fix I'm carrying in my perf/core branch,

Regards,

- Arnaldo

commit 98bb09f90a0ae33125fabc8f41529345382f1498
Author: Arnaldo Carvalho de Melo [off-list ref]
Date:   Wed Nov 27 09:26:54 2019 -0300

    libbpf: Use PRIu64 for sym->st_value to fix build on 32-bit arches

    The st_value field is a 64-bit value, so use PRIu64 to fix this error on
    32-bit arches:

      In file included from libbpf.c:52:
      libbpf.c: In function 'bpf_program__record_reloc':
      libbpf_internal.h:59:22: error: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'Elf64_Addr' {aka 'const long long unsigned int'} [-Werror=format=]
        libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \
                            ^~~~~~~~~~
      libbpf_internal.h:62:27: note: in expansion of macro '__pr'
       #define pr_warn(fmt, ...) __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
                                 ^~~~
      libbpf.c:1822:4: note: in expansion of macro 'pr_warn'
          pr_warn("bad call relo offset: %lu\n", sym->st_value);
          ^~~~~~~
      libbpf.c:1822:37: note: format string is defined here
          pr_warn("bad call relo offset: %lu\n", sym->st_value);
                                         ~~^
                                         %llu

    Fixes: 1f8e2bcb2cd5 ("libbpf: Refactor relocation handling")
    Cc: Alexei Starovoitov [off-list ref]
    Cc: Andrii Nakryiko [off-list ref]
    Link: https://lkml.kernel.org/n/tip-iabs1wq19c357bkk84p7blif@git.kernel.org
    Signed-off-by: Arnaldo Carvalho de Melo [off-list ref]
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b20f82e58989..6b0eae5c8a94 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1819,7 +1819,7 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
                        return -LIBBPF_ERRNO__RELOC;
                }
                if (sym->st_value % 8) {
-                       pr_warn("bad call relo offset: %lu\n", sym->st_value);
+                       pr_warn("bad call relo offset: %" PRIu64 "\n", sym->st_value);
Looking at this more... I never liked this PRI stuff. It makes for
such unreadable code.
How about just typecasting st_value to (long) ?
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