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btf_encoder: Generate also .init functions 

Currently we skip functions under .init* sections, Removing the .init*
section check, BTF now contains also functions from .init* sections.

Andrii's explanation from email:

> ...                  I think we should just drop the __init check and
> include all the __init functions into BTF. There could be cases where
> we'd need to attach BPF programs to __init functions (e.g., bpf_lsm
> security cases), so having BTFs for those FUNCs are necessary as well.
> Ftrace currently disallows that, but it's only because no user-space
> application has a way to attach probes early enough. This might change
> in the future, so there is no need to invent special mechanisms now
> for bpf_iter function preservation. Let's just include all __init
> functions in BTF.

It's over ~2000 functions on my .config:

   $ bpftool btf dump file ./vmlinux | grep 'FUNC ' | wc -l
   41505
   $ bpftool btf dump file /sys/kernel/btf/vmlinux | grep 'FUNC ' | wc -l
   39256

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Jiri Olsa 2020-11-14 23:38:52 +01:00 committed by Arnaldo Carvalho de Melo
parent 25753e0396
commit d0cd007339
1 changed files with 2 additions and 41 deletions
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43
btf_encoder.c
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@ -30,10 +30,6 @@
struct funcs_layout {
unsigned long mcount_start;
unsigned long mcount_stop;
unsigned long init_begin;
unsigned long init_end;
unsigned long init_bpf_begin;
unsigned long init_bpf_end;
unsigned long mcount_sec_idx;
};
@ -105,16 +101,6 @@ static int addrs_cmp(const void *_a, const void *_b)
return *a < *b ? -1 : 1;
}
static bool is_init(struct funcs_layout *fl, unsigned long addr)
{
return addr >= fl->init_begin && addr < fl->init_end;
}
static bool is_bpf_init(struct funcs_layout *fl, unsigned long addr)
{
return addr >= fl->init_bpf_begin && addr < fl->init_bpf_end;
}
static int filter_functions(struct btf_elf *btfe, struct funcs_layout *fl)
{
unsigned long *addrs, count, offset, i;
@ -156,18 +142,11 @@ static int filter_functions(struct btf_elf *btfe, struct funcs_layout *fl)
/*
* Let's got through all collected functions and filter
* out those that are not in ftrace and init code.
* out those that are not in ftrace.
*/
for (i = 0; i < functions_cnt; i++) {
struct elf_function *func = &functions[i];
/*
* Do not enable .init section functions,
* but keep .init.bpf.preserve_type functions.
*/
if (is_init(fl, func->addr) && !is_bpf_init(fl, func->addr))
continue;
/* Make sure function is within ftrace addresses. */
if (bsearch(&func->addr, addrs, count, sizeof(addrs[0]), addrs_cmp)) {
/*
@ -494,29 +473,11 @@ static void collect_symbol(GElf_Sym *sym, struct funcs_layout *fl)
if (!fl->mcount_stop &&
!strcmp("__stop_mcount_loc", elf_sym__name(sym, btfe->symtab)))
fl->mcount_stop = sym->st_value;
if (!fl->init_begin &&
!strcmp("__init_begin", elf_sym__name(sym, btfe->symtab)))
fl->init_begin = sym->st_value;
if (!fl->init_end &&
!strcmp("__init_end", elf_sym__name(sym, btfe->symtab)))
fl->init_end = sym->st_value;
if (!fl->init_bpf_begin &&
!strcmp("__init_bpf_preserve_type_begin", elf_sym__name(sym, btfe->symtab)))
fl->init_bpf_begin = sym->st_value;
if (!fl->init_bpf_end &&
!strcmp("__init_bpf_preserve_type_end", elf_sym__name(sym, btfe->symtab)))
fl->init_bpf_end = sym->st_value;
}
static int has_all_symbols(struct funcs_layout *fl)
{
return fl->mcount_start && fl->mcount_stop &&
fl->init_begin && fl->init_end &&
fl->init_bpf_begin && fl->init_bpf_end;
return fl->mcount_start && fl->mcount_stop;
}
static int collect_symbols(struct btf_elf *btfe, bool collect_percpu_vars)