Add support for the stackleak feature. It initializes the stack with the
poison value before returning from system calls which improves the kernel
security.
At the same time, disables the plugin in EFI stub code because EFI stub
is out of scope for the protection.
Tested on Loongson-3A5000 (enable GCC_PLUGIN_STACKLEAK and LKDTM):
# echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT
# dmesg
lkdtm: Performing direct entry STACKLEAK_ERASING
lkdtm: stackleak stack usage:
high offset: 320 bytes
current: 448 bytes
lowest: 1264 bytes
tracked: 1264 bytes
untracked: 208 bytes
poisoned: 14528 bytes
low offset: 64 bytes
lkdtm: OK: the rest of the thread stack is properly erased
Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
If 'regs' points to a local stack variable, prepare_frametrace() stores
all registers to the stack. This confuses objtool as it expects them to
be restored from the stack later.
The stores don't affect stack tracing, so use unwind hints to hide them
from objtool.
Fixes the following warnings:
arch/loongarch/kernel/traps.o: warning: objtool: show_stack+0xe0: stack state mismatch: reg1[22]=-1+0 reg2[22]=-2-160
arch/loongarch/kernel/traps.o: warning: objtool: show_stack+0xe0: stack state mismatch: reg1[23]=-1+0 reg2[23]=-2-152
Fixes: cb8a2ef084 ("LoongArch: Add ORC stack unwinder support")
Reported-by: kernel test robot <lkp@intel.com>
Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/270cadd8040dda74db2307f23497bb68e65db98d.1743481539.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202503280703.OARM8SrY-lkp@intel.com/
To get the best stacktrace output, you can compile your userspace
programs with frame pointers (at least glibc + the app you are tracing).
1, export "CC = gcc -fno-omit-frame-pointer";
2, compile your programs with "CC";
3, use uprobe to get stacktrace output.
...
echo 'p:malloc /usr/lib64/libc.so.6:0x0a4704 size=%r4:u64' > uprobe_events
echo 'p:free /usr/lib64/libc.so.6:0x0a4d50 ptr=%r4:x64' >> uprobe_events
echo 'comm == "demo"' > ./events/uprobes/malloc/filter
echo 'comm == "demo"' > ./events/uprobes/free/filter
echo 1 > ./options/userstacktrace
echo 1 > ./options/sym-userobj
...
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Name "guess unwinder" comes from x86, it scans the stack and reports
every kernel text address it finds.
Unwinders can be used by dump_stack() and other stacktrace functions.
Three stages when we do unwind,
1) unwind_start(), the prapare of unwinding, fill unwind_state.
2) unwind_done(), judge whether the unwind process is finished or not.
3) unwind_next_frame(), unwind the next frame.
Add get_stack_info() to get stack info. At present we have irq stack and
task stack. The next_sp is the key info between two types of stacks.
Dividing unwinder helps to add new unwinders in the future.
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Some of the assembly in the LoongArch port seem to come from a
prehistoric time, when the assembler didn't even have support for the
ABI names we all come to know and love, thus used raw register numbers
which hampered readability.
The usages are found with a regex match inside arch/loongarch, then
manually adjusted for those non-definitions.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Add the exception and interrupt handling machanism for basic LoongArch
support.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
