The symbol table is extended every 10000 addition by using realloc(),
where data copy might occur to the new buffer.

To decrease the amount of possible data copy, let's change the table
to store the pointer.

The symbol type + symbol name part is appended at the end of
(struct sym_entry), and allocated together with the struct body.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>

I will use 'sym' for the point to struce sym_entry in the next commit.
Rename 'sym', 'stype' to 'name', 'type', which are more intuitive.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>

Since commit 5e5c4fa7 ("scripts/kallsyms: shrink table before
sorting it"), kallsyms_relative_base can be larger than _text, which
causes overflow when building the 32-bit kernel.

https://lkml.org/lkml/2019/12/7/156

This is because _text is, unless --all-symbols is specified, now
trimmed from the symbol table before record_relative_base() is called.

Handle the offset signedness also for kallsyms_relative_base. Introduce
a new helper, output_address(), to reduce the code duplication.

Fixes: 5e5c4fa7 ("scripts/kallsyms: shrink table before sorting it")
Reported-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>

These are set to zero without the explicit initializers.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Put the relevant code close together.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

There is no more reason to check the return value of
check_symbol_range().
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Collect the ignored patterns to is_ignored_symbol().
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Refactoring for shortening the code.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Unless the address range matters, symbols can be ignored earlier,
which avoids unneeded memory allocation.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Add 'const' where a function does not write to the pointer dereferenes.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

The callers of this function expect (unsigned char *). I do not see
a good reason to make this function return (void *).
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

You can do equivalent things with strspn(). I do not see noticeable
performance difference.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

sym_entry::sym is (unsigned char *) instead of (char *) because
kallsyms exploits the MSB for compression, and the characters are
used as the index of token_profit array.

However, it requires casting (unsigned char *) to (char *) in some
places since standard library functions such as strcmp(), strlen()
expect (char *).

Introduce a new helper, sym_name(), which advances the given pointer
by 1 and casts it to (char *).
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

l <= strlen(sym_name) is unnecessary for prefix matching.
strncmp() will do.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Since commit 6f00df24 ("[PATCH] Strip local symbols from kallsyms"),
all symbols starting '$' are ignored.

is_arm_mapping_symbol() particularly ignores $a, $t, etc. but it is
redundant.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Currently, record_relative_base() iterates over the entire table to
find the minimum address, but it is not efficient because we sort
the table anyway.

After sort_symbol(), the table is sorted by address. (kallsyms parses
the 'nm -n' output, so the data is already sorted by address, but this
commit does not rely on it.)

Move record_relative_base() after sort_symbols(), and take the first
non-absolute symbol value.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Currently, build_initial_tok_table() trims unused symbols, but it is
called after sort_symbols().

It is not efficient to sort the huge table that contains unused entries.
Shrink the table before sorting it.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

build_initial_tok_table() overwrites unused sym_entry to shrink the
table size. Before the entry is overwritten, table[i].sym must be freed
since it is malloc'ed data.

This fixes the 'definitely lost' report from valgrind. I ran valgrind
against x86_64_defconfig of v5.4-rc8 kernel, and here is the summary:

[Before the fix]

  LEAK SUMMARY:
     definitely lost: 53,184 bytes in 2,874 blocks

[After the fix]

  LEAK SUMMARY:
     definitely lost: 0 bytes in 0 blocks
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

This is not defined in the standard headers. #ifndef is unneeded.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

gcc asan instrumentation emits the following sequence to store frame pc
when the kernel is built with CONFIG_RELOCATABLE:
debug/vsprintf.s:
        .section        .data.rel.ro.local,"aw"
        .align  8
.LC3:
        .quad   .LASANPC4826@GOTOFF
.text
        .align  8
        .type   number, @function
number:
.LASANPC4826:

and in case reloc is issued for LASANPC label it also gets into .symtab
with the same address as actual function symbol:
$ nm -n vmlinux | grep 0000000001397150
0000000001397150 t .LASANPC4826
0000000001397150 t number

In the end kernel backtraces are almost unreadable:
[  143.748476] Call Trace:
[  143.748484] ([<000000002da3e62c>] .LASANPC2671+0x114/0x190)
[  143.748492]  [<000000002eca1a58>] .LASANPC2612+0x110/0x160
[  143.748502]  [<000000002de9d830>] print_address_description+0x80/0x3b0
[  143.748511]  [<000000002de9dd64>] __kasan_report+0x15c/0x1c8
[  143.748521]  [<000000002ecb56d4>] strrchr+0x34/0x60
[  143.748534]  [<000003ff800a9a40>] kasan_strings+0xb0/0x148 [test_kasan]
[  143.748547]  [<000003ff800a9bba>] kmalloc_tests_init+0xe2/0x528 [test_kasan]
[  143.748555]  [<000000002da2117c>] .LASANPC4069+0x354/0x748
[  143.748563]  [<000000002dbfbb16>] do_init_module+0x136/0x3b0
[  143.748571]  [<000000002dbff3f4>] .LASANPC3191+0x2164/0x25d0
[  143.748580]  [<000000002dbffc4c>] .LASANPC3196+0x184/0x1b8
[  143.748587]  [<000000002ecdf2ec>] system_call+0xd8/0x2d8

Since LASANPC labels are not even unique and get into .symtab only due
to relocs filter them out in kallsyms.
Signed-off-by: NVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

<asm/bitsperlong.h> is enough to include the definition of
BITS_PER_LONG.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Global variables in the .bss section are zeroed out before the program
starts to run.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Fix the following sparse warnings:

scripts/kallsyms.c:65:5: warning: symbol 'token_profit' was not declared. Should it be static?
scripts/kallsyms.c:68:15: warning: symbol 'best_table' was not declared. Should it be static?
scripts/kallsyms.c:69:15: warning: symbol 'best_table_len' was not declared. Should it be static?

Also, remove 'inline' from is_arm_mapping_symbol(). The compiler
will inline it anyway when it is appropriate to do so.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

When checking for symbols with excessively long names,
account for null terminating character.

Fixes: f3462aa9 ("Kbuild: Handle longer symbols in kallsyms.c")
Signed-off-by: NEugene Loh <eugene.loh@oracle.com>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

As mentioned in the info pages of gas, the '.align' pseudo op's
interpretation of the alignment value is architecture specific.
It might either be a byte value or taken to the power of two.

On ARM it's actually the latter which leads to unnecessary large
alignments of 16 bytes for 32 bit builds or 256 bytes for 64 bit
builds.

Fix this by switching to '.balign' instead which is consistent
across all architectures.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

These symbols were added by commit 028f0426 ("kallsyms: support
kernel symbols in Blackfin on-chip memory") for Blackfin.

The Blackfin support was removed by commit 4ba66a97 ("arch: remove
blackfin port").
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Both kallsyms_num_syms and kallsyms_markers[] don't really need to use
unsigned long as their (base) types; unsigned int fully suffices.
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

scripts/kallsyms.c: function write_src:
"printf", the #1 format specifier "d" need arg type "int",
but the according arg "table_cnt" has type "unsigned int"

scripts/recordmcount.c: function do_file:
"fprintf", the #1 format specifier "d" need arg type "int",
but the according arg "(*w2)(ehdr->e_machine)" has type "unsigned int"

scripts/recordmcount.h: function find_secsym_ndx:
"fprintf", the #1 format specifier "d" need arg type "int",
but the according arg "txtndx" has type "unsigned int"
Signed-off-by: Nnixiaoming <nixiaoming@huawei.com>
Acked-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX was selected by BLACKFIN, METAG.
They were removed by commit 4ba66a97 ("arch: remove blackfin port"),
commit bb6fb6df ("metag: Remove arch/metag/"), respectively.

No more architecture enables CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX,
hence the --symbol-prefix option is unnecessary.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NSam Ravnborg <sam@ravnborg.org>

On arm64, the EFI stub and the kernel proper are essentially the same
binary, although the EFI stub executes at a different virtual address
as the kernel. For this reason, the EFI stub is restricted in the
symbols it can link to, which is ensured by prefixing all EFI stub
symbols with __efistub_ (and emitting __efistub_ prefixed aliases for
routines that may be shared between the core kernel and the stub)

These symbols are leaking into kallsyms, polluting the namespace, so
let's filter them explicitly.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Signed-off-by: NCao jin <caoj.fnst@cn.fujitsu.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

gcc on aarch64 may emit synbols of type 'n' if the kernel is built with
'-frecord-gcc-switches'.  In most cases, those symbols are reported with
nm as

	000000000000000e n $d

and with objdump as

	0000000000000000 l    d  .GCC.command.line	0000000000000000 .GCC.command.line
	000000000000000e l       .GCC.command.line	0000000000000000 $d

Those symbols are detected in is_arm_mapping_symbol() and ignored.
However, if "--prefix-symbols=<prefix>" is configured as well, the
situation is different.  For example, in efi/libstub, arm64 images are
built with

	'--prefix-alloc-sections=.init --prefix-symbols=__efistub_'.

In combination with '-frecord-gcc-switches', the symbols are now reported
by nm as:

	000000000000000e n __efistub_$d
and by objdump as:
	0000000000000000 l    d  .GCC.command.line	0000000000000000 .GCC.command.line
	000000000000000e l       .GCC.command.line	0000000000000000 __efistub_$d

Those symbols are no longer ignored and included in the base address
calculation.  This results in a base address of 000000000000000e, which
in turn causes kallsyms to abort with

    kallsyms failure:
	relative symbol value 0xffffff900800a000 out of range in relative mode

The problem is seen in little endian arm64 builds with CONFIG_EFI
enabled and with '-frecord-gcc-switches' set in KCFLAGS.

Explicitly ignore symbols of type 'n' since those are clearly debug
symbols.

Link: http://lkml.kernel.org/r/1507136063-3139-1-git-send-email-linux@roeck-us.netSigned-off-by: NGuenter Roeck <linux@roeck-us.net>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This add the kbuild infrastructure that will allow architectures to emit
vmlinux symbol CRCs as 32-bit offsets to another location in the kernel
where the actual value is stored. This works around problems with CRCs
being mistaken for relocatable symbols on kernels that self relocate at
runtime (i.e., powerpc with CONFIG_RELOCATABLE=y)

For the kbuild side of things, this comes down to the following:

 - introducing a Kconfig symbol MODULE_REL_CRCS

 - adding a -R switch to genksyms to instruct it to emit the CRC symbols
   as references into the .rodata section

 - making modpost distinguish such references from absolute CRC symbols
   by the section index (SHN_ABS)

 - making kallsyms disregard non-absolute symbols with a __crc_ prefix
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The implementation of the --page-offset kallsyms command line option has
been removed, so remove it from the usage string as well.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NMichal Marek <mmarek@suse.com>

The --page-offset command line option was only used for ARM, to filter
symbol addresses below CONFIG_PAGE_OFFSET. This is no longer needed, so
remove the functionality altogether.
Acked-by: NNicolas Pitre <nico@linaro.org>
Acked-by: NChris Brandt <chris.brandt@renesas.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

On ARM, the linker may emit veneers to deal with relative branch
instructions that appear too far away from their targets. Since the
second kallsyms pass results in an increase of the kernel size, it may
result in additional veneers to be emitted, potentially affecting the
output of kallsyms itself if these symbols are visible to it, and for
that reason, symbols whose names end in '_veneer' are ignored explicitly.

However, when building Thumb2 kernels, such veneers are named differently
if they also incur a mode switch, and since they are not filtered by
kallsyms, they may cause the build to fail. So filter symbols whose names
end in '_from_arm' or '_from_thumb' as well.
Tested-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Similar to how relative extables are implemented, it is possible to emit
the kallsyms table in such a way that it contains offsets relative to
some anchor point in the kernel image rather than absolute addresses.

On 64-bit architectures, it cuts the size of the kallsyms address table
in half, since offsets between kernel symbols can typically be expressed
in 32 bits.  This saves several hundreds of kilobytes of permanent
.rodata on average.  In addition, the kallsyms address table is no
longer subject to dynamic relocation when CONFIG_RELOCATABLE is in
effect, so the relocation work done after decompression now doesn't have
to do relocation updates for all these values.  This saves up to 24
bytes (i.e., the size of a ELF64 RELA relocation table entry) per value,
which easily adds up to a couple of megabytes of uncompressed __init
data on ppc64 or arm64.  Even if these relocation entries typically
compress well, the combined size reduction of 2.8 MB uncompressed for a
ppc64_defconfig build (of which 2.4 MB is __init data) results in a ~500
KB space saving in the compressed image.

Since it is useful for some architectures (like x86) to retain the
ability to emit absolute values as well, this patch also adds support
for capturing both absolute and relative values when
KALLSYMS_ABSOLUTE_PERCPU is in effect, by emitting absolute per-cpu
addresses as positive 32-bit values, and addresses relative to the
lowest encountered relative symbol as negative values, which are
subtracted from the runtime address of this base symbol to produce the
actual address.

Support for the above is enabled by default for all architectures except
IA-64 and Tile-GX, whose symbols are too far apart to capture in this
manner.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Reviewed-by: NKees Cook <keescook@chromium.org>
Tested-by: NKees Cook <keescook@chromium.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit c6bda7c9 ("kallsyms: fix percpu vars on x86-64 with
relocation") overloaded the 'A' (absolute) symbol type to signify that a
symbol is not subject to dynamic relocation.  However, the original A
type does not imply that at all, and depending on the version of the
toolchain, many A type symbols are emitted that are in fact relative to
the kernel text, i.e., if the kernel is relocated at runtime, these
symbols should be updated as well.

For instance, on sparc32, the following symbols are emitted as absolute
(kindly provided by Guenter Roeck):

  f035a420 A _etext
  f03d9000 A _sdata
  f03de8c4 A jiffies
  f03f8860 A _edata
  f03fc000 A __init_begin
  f041bdc8 A __init_text_end
  f0423000 A __bss_start
  f0423000 A __init_end
  f044457d A __bss_stop
  f044457d A _end

On x86_64, similar behavior can be observed:

  ffffffff81a00000 A __end_rodata_hpage_align
  ffffffff81b19000 A __vvar_page
  ffffffff81d3d000 A _end

Even if only a couple of them pass the symbol range check that results
in them to be taken into account for the final kallsyms symbol table, it
is obvious that 'A' does not mean the symbol does not need to be updated
at relocation time, and overloading its meaning to signify that is
perhaps not a good idea.

So instead, add a new percpu_absolute member to struct sym_entry, and
when --absolute-percpu is in effect, use it to record symbols whose
addresses should be emitted as final values rather than values that
still require relocation at runtime.  That way, we can drop the check
against the 'A' type.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Reviewed-by: NKees Cook <keescook@chromium.org>
Tested-by: NKees Cook <keescook@chromium.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michal Marek <mmarek@suse.cz>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since we have required at least GCC v3.2 for some time now, we
can drop the special handling of the 'gcc[0-9]_compiled.' label
which is not emitted anymore since GCC v3.0.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

When linking large kernels on ARM, the linker will insert veneers
(i.e., PLT like stubs) when function symbols are out of reach for
the ordinary relative branch/branch-and-link instructions.

However, due to the fact that the kallsyms region sits in .rodata,
which is between .text and .init.text, additional veneers may be
emitted in the second pass due to the fact that the size of the
kallsyms region itself has pushed the .init.text section further
apart, requiring even more veneers.

So ignore the veneers when generating the symbol table. Veneers
have no corresponding source code, and they will not turn up in
backtraces anyway.

This patch also lightly refactors the symbol_valid() function
to use a local 'sym_name' rather than the obfuscated 'sym + 1'
and 'sym + offset'
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>