As we may have, say, both a typedef and a struct with the same name and
sometimes we need to emit both to reflect some types found in the Linux
kernel that use:
typedef struct foo {
...
} foo;
So we need both 'struct foo' and 'typedef foo'.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To avoid emitting:
enum x86_intercept_stage {
};
Which isn't compilable.
The DWARF info for this enum in the Linux kernel has the declaration
flag set, but somehow this is not being available when loading from BTF.
So do the best we can at this enumeration__fprintf() time, that is to
just print zero members enumerations as a forward declaration.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
There are tools that don't set conf_load->conf_fprintf, like codiff, so
check for that in dwarves__resolve_cacheline_size().
Cc: Douglas Raillard <douglas.raillard@arm.com>
Fixes: 772725a77d ("dwarves_fprintf: Move cacheline_size into struct conf_fprintf")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tldr;
gdb pfunct
(gdb) run --compile tcp.o
Program received signal SIGFPE, Arithmetic exception.
0x00007ffff7f18551 in class__fprintf_cacheline_boundary (conf=0x7fffffffda10, offset=0, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:1319
1319 uint32_t cacheline = offset / conf->cacheline_size;
(gdb) bt
#0 0x00007ffff7f18551 in class__fprintf_cacheline_boundary (conf=0x7fffffffda10, offset=0, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:1319
#1 0x00007ffff7f16af2 in class_member__fprintf (member=0x45de10, union_member=false, type=0x45dfb0, cu=0x435a40, conf=0x7fffffffda10, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:869
#2 0x00007ffff7f1717b in struct_member__fprintf (member=0x45de10, type=0x45dfb0, cu=0x435a40, conf=0x7fffffffda10, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:983
#3 0x00007ffff7f1945c in __class__fprintf (class=0x45dcc0, cu=0x435a40, conf=0x7fffffffdbb0, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:1583
#4 0x00007ffff7f1a6bd in tag__fprintf (tag=0x45dcc0, cu=0x435a40, conf=0x7fffffffdc70, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:1906
#5 0x00007ffff7fbf022 in type__emit (tag=0x45dcc0, cu=0x435a40, prefix=0x0, suffix=0x0, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:333
#6 0x00007ffff7fbed3d in tag__emit_definitions (tag=0x6b21e0, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:265
#7 0x00007ffff7fbef45 in type__emit_definitions (tag=0x6b20c0, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:315
#8 0x00007ffff7fbed15 in tag__emit_definitions (tag=0x6b3b40, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:264
#9 0x00007ffff7fbef45 in type__emit_definitions (tag=0x6b31d0, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:315
#10 0x00007ffff7fbed15 in tag__emit_definitions (tag=0x4cb920, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:264
#11 0x00007ffff7fbef45 in type__emit_definitions (tag=0x4cb7d0, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:315
#12 0x0000000000403592 in function__emit_type_definitions (func=0x738ad0, cu=0x435a40, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/pfunct.c:353
#13 0x0000000000403670 in function__show (func=0x738ad0, cu=0x435a40) at /var/home/acme/git/pahole/pfunct.c:371
#14 0x00000000004038e9 in cu_function_iterator (cu=0x435a40, cookie=0x0) at /var/home/acme/git/pahole/pfunct.c:404
#15 0x00007ffff7f1296b in cus__for_each_cu (cus=0x4369e0, iterator=0x403869 <cu_function_iterator>, cookie=0x0, filter=0x0) at /var/home/acme/git/pahole/dwarves.c:1919
#16 0x000000000040432a in main (argc=3, argv=0x7fffffffe1f8) at /var/home/acme/git/pahole/pfunct.c:776
(gdb) p conf->cacheline_size
$2 = 0
We need to pass a conf_fprintf pointer to the chain starting with
function__emit_type_definitions(), i.e. dwarves_emit.c needs to receive
the printing configuration instead of, right at type__emit() synthesize
a conf_fprintf without initializing conf_fprintf->cacheline_size which
ends up in a division by zero.
But to fix this quicker just add a helper that checks if it is zero and
uses the conf_fprintf__defaults.cacheline_size field that is being
initialized by all tools via:
dwarves__resolve_cacheline_size(&conf_load, 0);
Fixes: 772725a77d ("dwarves_fprintf: Move cacheline_size into struct conf_fprintf")
Cc: Douglas Raillard <douglas.raillard@arm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add interfaces to allow users of dwarf_loader to prepare and pass
per-thread data to steal-functions running on worker threads.
Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Link: https://lore.kernel.org/r/20220126192039.2840752-3-kuifeng@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
We use this in both the dwarf_loader.c and in fprintf.c, so define it in
dwarves.h that is included in both.
Reported-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/all/YbkTAPn3EEu6BUYR@archlinux-ax161
Cc: Domenico Andreoli <domenico.andreoli@linux.com>
Cc: Douglas RAILLARD <douglas.raillard@arm.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Jan Engelhardt <jengelh@inai.de>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Matteo Croce <mcroce@microsoft.com>
Cc: Matthias Schwarzott <zzam@gentoo.org>
Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This reverts commit 7c5e35b63b.
Dropped since it could not cope with recursive types. A new attempt will
be made on 1.24.
Signed-off-by: Douglas RAILLARD <douglas.raillard@arm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This reverts commit 005236c3e4.
Dropped since it could not cope with recursive types. A new attempt will
be made on 1.24.
Signed-off-by: Douglas RAILLARD <douglas.raillard@arm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Allow making inner struct enums and union anonymous, so that when using
-E to expand types we don't end up with multiple definitions for
expanded inner structs, allowing the resulting expanded struct to be
compilable.
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
[ Applied it manually to cover some fuzz due to other patches ]
Link: https://lore.kernel.org/all/20211019100724.325570-2-douglas.raillard@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
In the past we saw the value of being able to disable specific features
due to problems in in its implementation, allowing users to use a subset
of functionality, without the problematic one.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
In the past we saw the value of being able to disable specific features
due to problems in in its implementation, allowing users to use a subset
of functionality, without the problematic one.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
LLVM patches ([1] for clang, [2] and [3] for BPF backend)
added support for btf_type_tag attributes. The following is
an example:
[$ ~] cat t.c
#define __tag1 __attribute__((btf_type_tag("tag1")))
#define __tag2 __attribute__((btf_type_tag("tag2")))
int __tag1 * __tag1 __tag2 *g __attribute__((section(".data..percpu")));
[$ ~] clang -O2 -g -c t.c
[$ ~] llvm-dwarfdump --debug-info t.o
t.o: file format elf64-x86-64
...
0x0000001e: DW_TAG_variable
DW_AT_name ("g")
DW_AT_type (0x00000033 "int **")
DW_AT_external (true)
DW_AT_decl_file ("/home/yhs/t.c")
DW_AT_decl_line (3)
DW_AT_location (DW_OP_addr 0x0)
0x00000033: DW_TAG_pointer_type
DW_AT_type (0x0000004b "int *")
0x00000038: DW_TAG_LLVM_annotation
DW_AT_name ("btf_type_tag")
DW_AT_const_value ("tag1")
0x00000041: DW_TAG_LLVM_annotation
DW_AT_name ("btf_type_tag")
DW_AT_const_value ("tag2")
0x0000004a: NULL
0x0000004b: DW_TAG_pointer_type
DW_AT_type (0x0000005a "int")
0x00000050: DW_TAG_LLVM_annotation
DW_AT_name ("btf_type_tag")
DW_AT_const_value ("tag1")
0x00000059: NULL
0x0000005a: DW_TAG_base_type
DW_AT_name ("int")
DW_AT_encoding (DW_ATE_signed)
DW_AT_byte_size (0x04)
0x00000061: NULL
From the above example, you can see that DW_TAG_pointer_type may contain
one or more DW_TAG_LLVM_annotation btf_type_tag tags. If
DW_TAG_LLVM_annotation tags are present inside DW_TAG_pointer_type, for
BTF encoding, pahole will need to follow [3] to generate a type chain
like:
var -> ptr -> tag2 -> tag1 -> ptr -> tag1 -> int
This patch implemented dwarf_loader support. If a pointer type contains
DW_TAG_LLVM_annotation tags, a new type btf_type_tag_ptr_type will be
created which will store the pointer tag itself and all
DW_TAG_LLVM_annotation tags. During recoding stage, the type chain will
be formed properly based on the above example.
An option "--skip_encoding_btf_type_tag" is added to disable
this new functionality.
[1] https://reviews.llvm.org/D111199
[2] https://reviews.llvm.org/D113222
[3] https://reviews.llvm.org/D113496
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: kernel-team@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Move DW_TAG_LLVM_annotation definition from dwarf_load.c to dutil.h as
it will be used later for btf_encoder.c. There is no functionality
change for this patch.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: kernel-team@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Sync up to commit 94a49850c5ee61ea ("Makefile: enforce gnu89 standard").
This is needed to support BTF_KIND_TYPE_TAG.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: kernel-team@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
$ pahole ~/c/split/foo.o
WARNING: DW_TAG_skeleton_unit used, please look for a .dwo file and use it instead.
A future version of pahole will support do this automagically.
$
Reported-by: https://twitter.com/trass3r
Link: https://github.com/acmel/dwarves/issues/23
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Now we know what that 0x4a thing is:
$ pahole ~/c/split/foo.o
die__process: DW_TAG_compile_unit, DW_TAG_type_unit or DW_TAG_partial_unit expected got skeleton_unit (0x4a)!
$
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
So that we can get it from user reports, i.e. instead of:
die__process: DW_TAG_compile_unit, DW_TAG_type_unit or DW_TAG_partial_unit expected got INVALID
We now get:
die__process: DW_TAG_compile_unit, DW_TAG_type_unit or DW_TAG_partial_unit expected got INVALID (0x4a)
That we can then look in dwarf.h and notice that there is this new:
DW_TAG_skeleton_unit = 0x4a,
Now lets go support it...
Reported-by: https://twitter.com/trass3r
Link: https://github.com/acmel/dwarves/issues/23
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
llvm commit ([1]) added support for btf_decl_tag attribute
with typedef declaration. Eventually, DW_TAG_LLVM_annotation
tag may appear inside dwarf typedef declaration tag.
kernel support for typedef BTF_KIND_DECL_TAG support
is introduced in [2]. There is no additional libbpf
change needed as the previous libbpf BTF_KIND_DECL_TAG
support is generic enough to cover new typedef use
cases.
This patch added parsing of DW_TAG_LLVM_annotation
for dwarf typedef decl.
$ cat t.c
$ clang -O2 -g -c t.c
$ llvm-dwarfdump --debug-info t.o
......
0x00000033: DW_TAG_typedef
DW_AT_type (0x00000051 "structure ")
DW_AT_name ("__t")
DW_AT_decl_file ("/home/yhs/t.c")
DW_AT_decl_line (3)
0x0000003e: DW_TAG_LLVM_annotation
DW_AT_name ("btf_decl_tag")
DW_AT_const_value ("tag1")
0x00000047: DW_TAG_LLVM_annotation
DW_AT_name ("btf_decl_tag")
DW_AT_const_value ("tag2")
0x00000050: NULL
Previously, pahole will issue a warning if typedef tag
contains any child tag. I removed this warning since
it is not true any more. Note that dwarf standard doesn't
prevent typedef decl tag from having nested tags.
In the future if we need to process any tag inside
typedef tag, we can just add code to process it.
[1] https://reviews.llvm.org/D110127
[2] https://lore.kernel.org/bpf/20211021195628.4018847-1-yhs@fb.com
Signed-off-by: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: kernel-team@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When the alignment is larger than natural, it is very likely that the
source code was using the cacheline size. Therefore, use the cacheline
size when it would only result in increasing the alignment.
Committer tests:
This is one of the cases that this heuristic works well, 'struct Qdisc'
in the Linux kernel:
--- /tmp/btfdiff.dwarf.pXdgRU 2021-10-28 10:22:11.738200232 -0300
+++ /tmp/btfdiff.btf.bkDkdf 2021-10-28 10:22:11.925205061 -0300
@@ -107,7 +107,7 @@ struct Qdisc {
/* XXX 24 bytes hole, try to pack */
/* --- cacheline 2 boundary (128 bytes) --- */
- struct sk_buff_head gso_skb __attribute__((__aligned__(64))); /* 128 24 */
+ struct sk_buff_head gso_skb __attribute__((__aligned__(32))); /* 128 24 */
struct qdisc_skb_head q; /* 152 24 */
struct gnet_stats_basic_packed bstats; /* 176 16 */
/* --- cacheline 3 boundary (192 bytes) --- */
With this patch both DWARF and BTF generated output have the same
alignment.
Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Give access to struct conf_load in class__infer_alignment.
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Remove the global variable and turn it into a member in struct
conf_fprintf, so that it can be used by other parts of the code.
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Now that the alignment attributes are being inferred from BTF we need to
suppress it in btfdiff, as we can't infer for some cases, like when the
field is naturally aligned.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
BTF does not carry alignment information, but it carries the offset in
structs. This allows inferring the original alignment, yielding a C
header dump that is not identical to the original C code, but is
guaranteed to lead to the same memory layout.
This allows using the output of pahole in another program to poke at
memory, with the assurance that we will not read garbage.
Note: Since the alignment is inferred from the offset, it sometimes
happens that the offset was already correctly aligned, which means the
inferred alignment will be smaller than in the original source. This
does not impact the ability to read existing structs, but it could
impact creating such struct if other client code expects higher
alignment than the one exposed in the generated header.
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Cc: dwarves@vger.kernel.org
[ Split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
We'll use it in the BTF loader.
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
[ Split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
We just need to record if we printed it for a member and if so, deduce
that from the number of spaces left to print before the end of line
comment (offset, size).
Fixes: a59459bb80 ("fprintf: Account inline type __aligned__ member types for spacing")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Kernel commit ([1]) renamed btf_tag to btf_decl_tag for uapi btf.h and
libbpf api's. The reason is a new clang attribute, btf_type_tag, is
introduced ([2]). Renaming btf_tag to btf_decl_tag makes it easier to
distinghish from btf_type_tag.
I also pulled in latest libbpf repo since it contains renamed libbpf api
function btf__add_decl_tag().
[1] https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com/
[2] https://reviews.llvm.org/D111199
Signed-off-by: Yonghong Song <yhs@fb.com>
[ Minor fixups to cope with --skip_missing ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
A typo, some escaping for paths and the header for an option.
Signed-off-by: Domenico Andreoli <domenico.andreoli@linux.com>
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Refactor class__fixup_btf_bitfields to remove a "continue" statement, to
prepare the ground for alignment fixup that is relevant for some types
matching:
type->tag != DW_TAG_base_type && type->tag != DW_TAG_enumeration_type
Committer testing:
btfdiff passes for a x86_64 kernel built with gcc and for a clang
thin-LTO vmlinux build.
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add a --skip_missing option that allows pahole to keep going in case one
of the type passed to -C (e.g. via a file) does not exist.
This is useful for intropsection software such as debugging kernel
modules that can handle various kernel configurations and versions for
which some recently added types are missing. The consumer of the header
becomes responsible of gating the uses of the type with #ifdef
CONFIG_XXX, rather than pahole bailing out on the first unknown type.
Committer testing:
Before:
$ pahole tcp_splice_state,xxfrm_policy_queue,list_head tcp.o
struct tcp_splice_state {
struct pipe_inode_info * pipe; /* 0 8 */
size_t len; /* 8 8 */
unsigned int flags; /* 16 4 */
/* size: 24, cachelines: 1, members: 3 */
/* padding: 4 */
/* last cacheline: 24 bytes */
};
pahole: type 'xxfrm_policy_queue' not found
$
After:
$ pahole --help |& grep skip
--skip=COUNT Skip COUNT input records
--skip_encoding_btf_tag Do not encode TAGs in BTF.
--skip_encoding_btf_vars Do not encode VARs in BTF.
--skip_missing skip missing types passed to -C rather than stop
$ pahole --skip_missing tcp_splice_state,xxfrm_policy_queue,list_head tcp.o
struct tcp_splice_state {
struct pipe_inode_info * pipe; /* 0 8 */
size_t len; /* 8 8 */
unsigned int flags; /* 16 4 */
/* size: 24, cachelines: 1, members: 3 */
/* padding: 4 */
/* last cacheline: 24 bytes */
};
struct list_head {
struct list_head * next; /* 0 8 */
struct list_head * prev; /* 8 8 */
/* size: 16, cachelines: 1, members: 2 */
/* last cacheline: 16 bytes */
};
pahole: type 'xxfrm_policy_queue' not found
$
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This code:
struct X {
struct {
} __attribute__((foo)) x __attribute__((bar));
}
Was wrongly printed as:
struct X {
struct {
} x __attribute__((foo)) __attribute__((bar));
}
This unfortunately matters a lot, since "bar" is suppose to apply to
"x", but "foo" to typeof(x). In the wrong form, both apply to "x",
leading to e.g. incorrect layout for __aligned__ attribute.
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
pahole does not generate VARs for percpu symbols on s390. A percpu
symbol definition on a typical x86_64 kernel looks like this:
[33] .data..percpu PROGBITS 0000000000000000 01c00000
^^^^^^^^^^^^^^^^ sh_addr
LOAD 0x0000000001c00000 0x0000000000000000 0x000000000286f000
^^^^^^^^^^^^^^^^^^ p_vaddr
13559: 000000000001ba50 4 OBJECT LOCAL DEFAULT 33 cpu_profile_flip
^^^^^^^^^^^^^^^^ st_value
Most importantly, .data..percpu's sh_addr is 0, and this is what pahole
is currently assuming. However, on s390 this is different:
[37] .data..percpu PROGBITS 00000000019cd000 018ce000
^^^^^^^^^^^^^^^^ sh_addr
LOAD 0x000000000136e000 0x000000000146d000 0x000000000146d000
^^^^^^^^^^^^^^^^^^ p_vaddr
80377: 0000000001ba1440 4 OBJECT WEAK DEFAULT 37 cpu_profile_flip
^^^^^^^^^^^^^^^^ st_value
Fix by restructuring the code to always use section-relative offsets for
symbols. Change the comment to focus on this invariant.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Variables can be allocated with or without specification, however,
tag__recode_dwarf_type() always tries accessing it, leading to heap read
overflows and subsequent logic bugs.
Fix by introducing a bit that tracks whether or not specification is
present.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Will be called when a thread exits, initially only in the DWARF loader,
so that pahole can call the btf_encoder associated with the exiting
thread to do the dedup as the last step done in parallel.
Then we'll iterate the btf_encoders list and combine everything into the
first btf_encoder instance that gets then written to disk.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
I.e. the one in:
13ebb60ab66799ab libbpf: Add API that copies all BTF types from one BTF object to another
This will be used to paralellize the BTF encoding phase.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The following is an example with latest upstream clang:
$ cat t.c
#define __tag1 __attribute__((btf_tag("tag1")))
#define __tag2 __attribute__((btf_tag("tag2")))
struct t {
int a:1 __tag1;
int b __tag2;
} __tag1 __tag2;
int g __tag1 __attribute__((section(".data..percpu")));
int __tag1 foo(struct t *a1, int a2 __tag2) {
return a1->b + a2 + g;
}
$ clang -O2 -g -c t.c
$ pahole -JV t.o
Found per-CPU symbol 'g' at address 0x0
Found 1 per-CPU variables!
Found 1 functions!
File t.o:
[1] INT int size=4 nr_bits=32 encoding=SIGNED
[2] PTR (anon) type_id=3
[3] STRUCT t size=8
a type_id=1 bitfield_size=1 bits_offset=0
b type_id=1 bitfield_size=0 bits_offset=32
[4] TAG tag1 type_id=3 component_idx=0
[5] TAG tag2 type_id=3 component_idx=1
[6] TAG tag1 type_id=3 component_idx=-1
[7] TAG tag2 type_id=3 component_idx=-1
[8] FUNC_PROTO (anon) return=1 args=(2 a1, 1 a2)
[9] FUNC foo type_id=8
[10] TAG tag2 type_id=9 component_idx=1
[11] TAG tag1 type_id=9 component_idx=-1
search cu 't.c' for percpu global variables.
Variable 'g' from CU 't.c' at address 0x0 encoded
[12] VAR g type=1 linkage=1
[13] TAG tag1 type_id=12 component_idx=-1
[14] DATASEC .data..percpu size=4 vlen=1
type=12 offset=0 size=4
$ ...
With additional option --skip_encoding_btf_tag, pahole doesn't
generate BTF_KIND_TAGs any more.
$ pahole -JV --skip_encoding_btf_tag t.o
Found per-CPU symbol 'g' at address 0x0
Found 1 per-CPU variables!
Found 1 functions!
File t.o:
[1] INT int size=4 nr_bits=32 encoding=SIGNED
[2] PTR (anon) type_id=3
[3] STRUCT t size=8
a type_id=1 bitfield_size=1 bits_offset=0
b type_id=1 bitfield_size=0 bits_offset=32
[4] FUNC_PROTO (anon) return=1 args=(2 a1, 1 a2)
[5] FUNC foo type_id=4
search cu 't.c' for percpu global variables.
Variable 'g' from CU 't.c' at address 0x0 encoded
[6] VAR g type=1 linkage=1
[7] DATASEC .data..percpu size=4 vlen=1
type=6 offset=0 size=4
$ ...
Signed-off-by: Yonghong Song <yhs@fb.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: kernel-team@fb.com
Link: https://lore.kernel.org/r/20210922021332.2287418-1-yhs@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Parse the DWARF tag DW_TAG_LLVM_annotation. Only record annotations with
btf_tag name which corresponds to btf_tag attributes in C code. Such
information will be used later by the btf_encoder for BTF conversion.
The LLVM implementation only supports btf_tag annotations on
struct/union, func, func parameter and variable ([1]). So we only check
existence of corresponding DW tags in these places.
A flag "--skip_encoding_btf_tag" is introduced if for whatever reason
this feature needs to be disabled.
[1] https://reviews.llvm.org/D106614
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: kernel-team@fb.com
Link: https://lore.kernel.org/r/20210922021326.2287095-1-yhs@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The build system always download the libbpf submodule, regardless if
we're using the embedded or the system version.
Download the libbpf source only if we're using the embedded one.
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Latest upstream LLVM now supports to emit btf_tag to dwarf ([1]) and the
kernel support for btf_tag is also landed ([2]). Sync with latest libbpf
which has btf_tag support. Next step will be to implement dwarf -> btf
conversion for btf_tag.
[1] https://reviews.llvm.org/D106621
[2] https://lore.kernel.org/bpf/20210914223015.245546-1-yhs@fb.com
Signed-off-by: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: kernel-team@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
ostra-cg, which requires python, is installed in the destination dir.
Make it optional for embedded distributions which doesn't have the
python interpreter available.
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Useful while developing to help in tuning the ptr tables (types, tags,
functions, maybe some more in the future).
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Arnaldo Carvalho de Melo
Kui-Feng Lee
Douglas RAILLARD
Yonghong Song
Domenico Andreoli
Ilya Leoshkevich
Matteo Croce