Add new folders arch/arm64/kvm/hyp/{vhe,nvhe} and Makefiles for building code
that runs in EL2 under VHE/nVHE KVM, repsectivelly. Add an include folder for
hyp-specific header files which will include code common to VHE/nVHE.
Build nVHE code with -D__KVM_NVHE_HYPERVISOR__, VHE code with
-D__KVM_VHE_HYPERVISOR__.
Under nVHE compile each source file into a `.hyp.tmp.o` object first, then
prefix all its symbols with "__kvm_nvhe_" using `objcopy` and produce
a `.hyp.o`. Suffixes were chosen so that it would be possible for VHE and nVHE
to share some source files, but compiled with different CFLAGS.
The nVHE ELF symbol prefix is added to kallsyms.c as ignored. EL2-only symbols
will never appear in EL1 stack traces.
Due to symbol prefixing, add a section in image-vars.h for aliases of symbols
that are defined in nVHE EL2 and accessed by kernel in EL1 or vice versa.
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-4-dbrazdil@google.com
Due to a bug-report that was compiler-dependent, I updated one of my
machines to gcc-10. That shows a lot of new warnings. Happily they
seem to be mostly the valid kind, but it's going to cause a round of
churn for getting rid of them..
This is the really low-hanging fruit of removing a couple of zero-sized
arrays in some core code. We have had a round of these patches before,
and we'll have many more coming, and there is nothing special about
these except that they were particularly trivial, and triggered more
warnings than most.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is the code in the read_symbol function in 'scripts/kallsyms.c':
if (is_ignored_symbol(name, type))
return NULL;
/* Ignore most absolute/undefined (?) symbols. */
if (strcmp(name, "_text") == 0)
_text = addr;
But the is_ignored_symbol function returns true for name="_text" and
type='A'. So the next condition is not executed and the _text variable
is always zero.
It makes the wrong kallsyms_relative_base symbol as a result of the code
(CONFIG_KALLSYMS_BASE_RELATIVE is defined):
if (base_relative) {
output_label("kallsyms_relative_base");
output_address(relative_base);
printf("\n");
}
Because the output_address function uses the _text variable.
So the kallsyms_lookup function and all related functions in the kernel
do not work properly. For example, the stack trace in oops:
Call Trace:
[aa095e58] [809feab8] kobj_ns_ops_tbl+0x7ff09ac8/0x7ff1c1c4 (unreliable)
[aa095e98] [80002b64] kobj_ns_ops_tbl+0x7f50db74/0x80000010
[aa095ef8] [809c3d24] kobj_ns_ops_tbl+0x7feced34/0x7ff1c1c4
[aa095f28] [80002ed0] kobj_ns_ops_tbl+0x7f50dee0/0x80000010
[aa095f38] [8000f238] kobj_ns_ops_tbl+0x7f51a248/0x80000010
The right stack trace:
Call Trace:
[aa095e58] [809feab8] module_vdu_video_init+0x2fc/0x3bc (unreliable)
[aa095e98] [80002b64] do_one_initcall+0x40/0x1f0
[aa095ef8] [809c3d24] kernel_init_freeable+0x164/0x1d8
[aa095f28] [80002ed0] kernel_init+0x14/0x124
[aa095f38] [8000f238] ret_from_kernel_thread+0x14/0x1c
[masahiroy@kernel.org:
This issue happens on binutils <= 2.22
The following commit fixed it:
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d2667025dd30611514810c28bee9709e4623012a
The symbol type of _text is 'T' on binutils >= 2.23
The minimal supported binutils version for the kernel build is 2.21
]
Signed-off-by: Mikhail Petrov <Mikhail.Petrov@mir.dev>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
memcpy() writes one more byte than allocated.
Fixes: 8d60526999 ("scripts/kallsyms: change table to store (strcut sym_entry *)")
Reported-by: youling257 <youling257@gmail.com>
Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Pavel Machek <pavel@ucw.cz>
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: Masahiro 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: Masahiro Yamada <masahiroy@kernel.org>
Since commit 5e5c4fa787 ("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: 5e5c4fa787 ("scripts/kallsyms: shrink table before sorting it")
Reported-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Unless the address range matters, symbols can be ignored earlier,
which avoids unneeded memory allocation.
Signed-off-by: Masahiro 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: Masahiro Yamada <yamada.masahiro@socionext.com>
You can do equivalent things with strspn(). I do not see noticeable
performance difference.
Signed-off-by: Masahiro 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: Masahiro Yamada <yamada.masahiro@socionext.com>
Since commit 6f00df24ee ("[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: Masahiro 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: Masahiro 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: Masahiro 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: Masahiro 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: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Pull Kbuild updates from Masahiro Yamada:
- do not generate unneeded top-level built-in.a
- let git ignore O= directory entirely
- optimize scripts/kallsyms slightly
- exclude DWARF info from *.s regardless of config options
- fix GCC toolchain search path for Clang to prepare ld.lld support
- do not generate modules.order when CONFIG_MODULES is disabled
- simplify single target rules and remove VPATH for external module
build
- allow to add optional flags to dpkg-buildpackage when building
deb-pkg
- move some compiler option tests from Makefile to Kconfig
- various Makefile cleanups
* tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits)
kbuild: remove scripts/basic/% build target
kbuild: use -Werror=implicit-... instead of -Werror-implicit-...
kbuild: clean up scripts/gcc-version.sh
kbuild: remove cc-version macro
kbuild: update comment block of scripts/clang-version.sh
kbuild: remove commented-out INITRD_COMPRESS
kbuild: move -gsplit-dwarf, -gdwarf-4 option tests to Kconfig
kbuild: [bin]deb-pkg: add DPKG_FLAGS variable
kbuild: move ".config not found!" message from Kconfig to Makefile
kbuild: invoke syncconfig if include/config/auto.conf.cmd is missing
kbuild: simplify single target rules
kbuild: remove empty rules for makefiles
kbuild: make -r/-R effective in top Makefile for old Make versions
kbuild: move tools_silent to a more relevant place
kbuild: compute false-positive -Wmaybe-uninitialized cases in Kconfig
kbuild: refactor cc-cross-prefix implementation
kbuild: hardcode genksyms path and remove GENKSYMS variable
scripts/gdb: refactor rules for symlink creation
kbuild: create symlink to vmlinux-gdb.py in scripts_gdb target
scripts/gdb: do not descend into scripts/gdb from scripts
...
