[PATCH v2 0/3] Fix objtool warning about do_syscall() on LoongArch

[PATCH v2 0/3] Fix objtool warning about do_syscall() on LoongArch

[Tiezhu Yang]

With this series, there is no objtool warning about do_syscall() and
there is handle_syscall() which is the previous frame of do_syscall()
in the call trace when running "echo l > /proc/sysrq-trigger", tested
with the following two configs:

(1) CONFIG_RANDOMIZE_KSTACK_OFFSET=y &&
    CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=n
(2) CONFIG_RANDOMIZE_KSTACK_OFFSET=y &&
    CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y

Tiezhu Yang (3):
  objtool/LoongArch: Decode secondary stack instruction
  objtool: Handle secondary stack related instructions
  LoongArch: Remove STACK_FRAME_NON_STANDARD(do_syscall)

 arch/loongarch/kernel/syscall.c         |  4 ----
 tools/arch/loongarch/include/asm/inst.h | 12 ++++++++++
 tools/objtool/arch/loongarch/decode.c   | 29 ++++++++++++++++++++++++-
 tools/objtool/check.c                   | 22 +++++++++++++++++++
 tools/objtool/include/objtool/elf.h     |  1 +
 5 files changed, 63 insertions(+), 5 deletions(-)

-- 
2.42.0

[PATCH v2 1/3] objtool/LoongArch: Decode secondary stack instruction

[Tiezhu Yang]

After commit a0f7085f6a63 ("LoongArch: Add RANDOMIZE_KSTACK_OFFSET
support"), there is a new instruction "sub.d $sp, $sp, $t0" for the
secondary stack in do_syscall(), then there exists a objtool warning
"do_syscall+0x11c: return with modified stack frame" and there is no
handle_syscall() which is the previous frame of do_syscall() in the
call trace when executing the command "echo l > /proc/sysrq-trigger".

In order to solve the above issues, the first step is to decode the
secondary stack instruction "sub.d $sp, $sp, $t0".

Cc: stable@vger.kernel.org # 6.9+
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 tools/arch/loongarch/include/asm/inst.h | 12 ++++++++++++
 tools/objtool/arch/loongarch/decode.c   | 21 +++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/tools/arch/loongarch/include/asm/inst.h b/tools/arch/loongarch/include/asm/inst.h
index c25b5853181d..935b596642e2 100644
--- a/tools/arch/loongarch/include/asm/inst.h
+++ b/tools/arch/loongarch/include/asm/inst.h
@@ -51,6 +51,10 @@ enum reg2i16_op {
 	bgeu_op		= 0x1b,
 };
 
+enum reg3_op {
+	subd_op		= 0x23,
+};
+
 struct reg0i15_format {
 	unsigned int immediate : 15;
 	unsigned int opcode : 17;
@@ -96,6 +100,13 @@ struct reg2i16_format {
 	unsigned int opcode : 6;
 };
 
+struct reg3_format {
+	unsigned int rd : 5;
+	unsigned int rj : 5;
+	unsigned int rk : 5;
+	unsigned int opcode : 17;
+};
+
 union loongarch_instruction {
 	unsigned int word;
 	struct reg0i15_format	reg0i15_format;
@@ -105,6 +116,7 @@ union loongarch_instruction {
 	struct reg2i12_format	reg2i12_format;
 	struct reg2i14_format	reg2i14_format;
 	struct reg2i16_format	reg2i16_format;
+	struct reg3_format	reg3_format;
 };
 
 #define LOONGARCH_INSN_SIZE	sizeof(union loongarch_instruction)
diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index aee479d2191c..db4dd05cdb49 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -272,6 +272,25 @@ static bool decode_insn_reg2i16_fomat(union loongarch_instruction inst,
 	return true;
 }
 
+static bool decode_insn_reg3_fomat(union loongarch_instruction inst,
+				   struct instruction *insn)
+{
+	switch (inst.reg3_format.opcode) {
+	case subd_op:
+		if ((inst.reg3_format.rd == CFI_SP) && (inst.reg3_format.rj == CFI_SP)) {
+			/*
+			 * sub.d sp,sp,t0
+			 * this is a rare case for the secondary stack.
+			 */
+		}
+		break;
+	default:
+		return false;
+	}
+
+	return true;
+}
+
 int arch_decode_instruction(struct objtool_file *file, const struct section *sec,
 			    unsigned long offset, unsigned int maxlen,
 			    struct instruction *insn)
@@ -303,6 +322,8 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 		return 0;
 	if (decode_insn_reg2i16_fomat(inst, insn))
 		return 0;
+	if (decode_insn_reg3_fomat(inst, insn))
+		return 0;
 
 	if (inst.word == 0)
 		insn->type = INSN_NOP;
-- 
2.42.0

[PATCH v2 2/3] objtool: Handle secondary stack related instructions

[Tiezhu Yang]

After commit a0f7085f6a63 ("LoongArch: Add RANDOMIZE_KSTACK_OFFSET
support"), there is a new instruction "sub.d $sp, $sp, $t0" for the
secondary stack in do_syscall(), then there exists a objtool warning
"do_syscall+0x11c: return with modified stack frame" and there is no
handle_syscall() which is the previous frame of do_syscall() in the
call trace when executing the command "echo l > /proc/sysrq-trigger".

objdump shows something like this:

0000000000000000 <do_syscall>:
   0:   02ff8063        addi.d          $sp, $sp, -32
   4:   29c04076        st.d            $fp, $sp, 16
   8:   29c02077        st.d            $s0, $sp, 8
   c:   29c06061        st.d            $ra, $sp, 24
  10:   02c08076        addi.d          $fp, $sp, 32
  ...
  74:   0011b063        sub.d           $sp, $sp, $t0
  ...
  a8:   4c000181        jirl            $ra, $t0, 0
  ...
  dc:   02ff82c3        addi.d          $sp, $fp, -32
  e0:   28c06061        ld.d            $ra, $sp, 24
  e4:   28c04076        ld.d            $fp, $sp, 16
  e8:   28c02077        ld.d            $s0, $sp, 8
  ec:   02c08063        addi.d          $sp, $sp, 32
  f0:   4c000020        jirl            $zero, $ra, 0

The instruction "sub.d $sp, $sp, $t0" changes the stack bottom
and the new stack size is a random value, in order to find the
return address of do_syscall() which is stored in the original
stack frame after executing "jirl $ra, $t0, 0", it should use
fp which points to the original stack top.

This is a rare case, add a member "secondary_stack" in the struct
symbol as a label to avoid affecting the current normal case, then
set it as true only if there exists the secondary stack instruction
"sub.d $sp, $sp, $t0", at last check this label for the other special
secondary stack instructions about fp to change the cfa base and cfa
offset during the period of secondary stack in update_cfi_state().

Tested with the following two configs:
(1) CONFIG_RANDOMIZE_KSTACK_OFFSET=y &&
    CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=n
(2) CONFIG_RANDOMIZE_KSTACK_OFFSET=y &&
    CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y

Cc: stable@vger.kernel.org # 6.9+
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 tools/objtool/arch/loongarch/decode.c |  8 +++++++-
 tools/objtool/check.c                 | 22 ++++++++++++++++++++++
 tools/objtool/include/objtool/elf.h   |  1 +
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index db4dd05cdb49..4085714ffd18 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -122,7 +122,7 @@ static bool decode_insn_reg2i12_fomat(union loongarch_instruction inst,
 	switch (inst.reg2i12_format.opcode) {
 	case addid_op:
 		if ((inst.reg2i12_format.rd == CFI_SP) || (inst.reg2i12_format.rj == CFI_SP)) {
-			/* addi.d sp,sp,si12 or addi.d fp,sp,si12 */
+			/* addi.d sp,sp,si12 or addi.d fp,sp,si12 or addi.d sp,fp,si12 */
 			insn->immediate = sign_extend64(inst.reg2i12_format.immediate, 11);
 			ADD_OP(op) {
 				op->src.type = OP_SRC_ADD;
@@ -275,6 +275,8 @@ static bool decode_insn_reg2i16_fomat(union loongarch_instruction inst,
 static bool decode_insn_reg3_fomat(union loongarch_instruction inst,
 				   struct instruction *insn)
 {
+	struct symbol *func;
+
 	switch (inst.reg3_format.opcode) {
 	case subd_op:
 		if ((inst.reg3_format.rd == CFI_SP) && (inst.reg3_format.rj == CFI_SP)) {
@@ -282,6 +284,10 @@ static bool decode_insn_reg3_fomat(union loongarch_instruction inst,
 			 * sub.d sp,sp,t0
 			 * this is a rare case for the secondary stack.
 			 */
+			func = find_func_containing(insn->sec, insn->offset);
+			if (!func)
+				return false;
+			func->secondary_stack = true;
 		}
 		break;
 	default:
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 01237d167223..c7b9942fee29 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2993,6 +2993,28 @@ static int update_cfi_state(struct instruction *insn,
 				break;
 			}
 
+			if (op->dest.reg == CFI_BP && op->src.reg == CFI_SP) {
+				/* addi.d fp,sp,imm for the secondary stack on LoongArch */
+				if (cfa->base == CFI_SP && cfa->offset == op->src.offset) {
+					if (insn->sym->secondary_stack) {
+						cfa->base = CFI_BP;
+						cfa->offset = 0;
+					}
+				}
+				break;
+			}
+
+			if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
+				/* addi.d sp,fp,imm for the secondary stack on LoongArch */
+				if (cfa->base == CFI_FP && cfa->offset == 0) {
+					if (insn->sym->secondary_stack) {
+						cfa->base = CFI_SP;
+						cfa->offset = -op->src.offset;
+					}
+				}
+				break;
+			}
+
 			if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
 
 				/* lea disp(%rbp), %rsp */
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 2b8a69de4db8..586916e0d441 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -68,6 +68,7 @@ struct symbol {
 	u8 warned	     : 1;
 	u8 embedded_insn     : 1;
 	u8 local_label       : 1;
+	u8 secondary_stack   : 1;
 	struct list_head pv_target;
 	struct reloc *relocs;
 };
-- 
2.42.0

Re: [PATCH v2 2/3] objtool: Handle secondary stack related instructions

[Tiezhu Yang]

On 08/05/2024 11:26 AM, Tiezhu Yang wrote:
> After commit a0f7085f6a63 ("LoongArch: Add RANDOMIZE_KSTACK_OFFSET
> support"), there is a new instruction "sub.d $sp, $sp, $t0" for the
> secondary stack in do_syscall(), then there exists a objtool warning
> "do_syscall+0x11c: return with modified stack frame" and there is no
> handle_syscall() which is the previous frame of do_syscall() in the
> call trace when executing the command "echo l > /proc/sysrq-trigger".

...

> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 01237d167223..c7b9942fee29 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -2993,6 +2993,28 @@ static int update_cfi_state(struct instruction *insn,
>  				break;
>  			}
>
> +			if (op->dest.reg == CFI_BP && op->src.reg == CFI_SP) {
> +				/* addi.d fp,sp,imm for the secondary stack on LoongArch */
> +				if (cfa->base == CFI_SP && cfa->offset == op->src.offset) {
> +					if (insn->sym->secondary_stack) {
> +						cfa->base = CFI_BP;
> +						cfa->offset = 0;
> +					}
> +				}
> +				break;
> +			}
> +
> +			if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
> +				/* addi.d sp,fp,imm for the secondary stack on LoongArch */
> +				if (cfa->base == CFI_FP && cfa->offset == 0) {

Here should be CFI_BP instead of CFI_FP which is only defined
for LoongArch.

> +					if (insn->sym->secondary_stack) {
> +						cfa->base = CFI_SP;
> +						cfa->offset = -op->src.offset;
> +					}
> +				}
> +				break;
> +			}
> +
>  			if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
>
>  				/* lea disp(%rbp), %rsp */

Oh, sorry, I forgot to test this change on x86.

Here is the test info on x86: the cfa->base is CFI_BP
or CFI_BP_INDIRECT and the cfa->offset is not 0
if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP),
thus it can check the following condition
if(cfa->base == CFI_BP && cfa->offset == 0)
to distinguish x86 and LoongArch.

So the correct change should be something like this
to make sure it works well for both x86 and LoongArch:

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 01237d167223..0832d20c95d2 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2993,10 +2993,28 @@ static int update_cfi_state(struct instruction 
*insn,
                                 break;
                         }

-                       if (op->dest.reg == CFI_SP && op->src.reg == 
CFI_BP) {
+                       if (op->dest.reg == CFI_BP && op->src.reg == 
CFI_SP) {
+                               /* addi.d fp,sp,imm for the secondary 
stack on LoongArch */
+                               if (cfa->base == CFI_SP && cfa->offset 
== op->src.offset) {
+                                       if (insn->sym->secondary_stack) {
+                                               cfa->base = CFI_BP;
+                                               cfa->offset = 0;
+                                       }
+                               }
+                               break;
+                       }

-                               /* lea disp(%rbp), %rsp */
-                               cfi->stack_size = -(op->src.offset + 
regs[CFI_BP].offset);
+                       if (op->dest.reg == CFI_SP && op->src.reg == 
CFI_BP) {
+                               /* addi.d sp,fp,imm for the secondary 
stack on LoongArch */
+                               if (cfa->base == CFI_BP && cfa->offset 
== 0) {
+                                       if (insn->sym->secondary_stack) {
+                                               cfa->base = CFI_SP;
+                                               cfa->offset = 
-op->src.offset;
+                                       }
+                               } else {
+                                       /* lea disp(%rbp), %rsp */
+                                       cfi->stack_size = 
-(op->src.offset + regs[CFI_BP].offset);
+                               }
                                 break;
                         }

I will wait for some days to get more review comments
and then send v3 later.

Thanks,
Tiezhu

Re: [PATCH v2 2/3] objtool: Handle secondary stack related instructions

[kernel test robot]

Hi Tiezhu,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.11-rc2 next-20240802]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Tiezhu-Yang/objtool-LoongArch-Decode-secondary-stack-instruction/20240805-113316
base:   linus/master
patch link:    https://lore.kernel.org/r/20240805032700.16038-3-yangtiezhu%40loongson.cn
patch subject: [PATCH v2 2/3] objtool: Handle secondary stack related instructions
config: x86_64-allmodconfig (https://download.01.org/0day-ci/archive/20240805/202408051602.NqvBpTsv-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240805/202408051602.NqvBpTsv-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408051602.NqvBpTsv-lkp@intel.com/

All errors (new ones prefixed by >>):

   scripts/genksyms/parse.y: warning: 9 shift/reduce conflicts [-Wconflicts-sr]
   scripts/genksyms/parse.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
   scripts/genksyms/parse.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
>> check.c:3009:22: error: use of undeclared identifier 'CFI_FP'
    3009 |                                 if (cfa->base == CFI_FP && cfa->offset == 0) {
         |                                                  ^
   1 error generated.
   make[5]: *** [tools/build/Makefile.build:105: tools/objtool/check.o] Error 1
   make[5]: *** Waiting for unfinished jobs....
   make[4]: *** [Makefile:70: tools/objtool/objtool-in.o] Error 2
   make[3]: *** [Makefile:72: objtool] Error 2
   make[2]: *** [Makefile:1360: tools/objtool] Error 2
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:224: __sub-make] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:224: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v2 2/3] objtool: Handle secondary stack related instructions

[Jinyang He]

On 2024-08-05 11:26, Tiezhu Yang wrote:

> After commit a0f7085f6a63 ("LoongArch: Add RANDOMIZE_KSTACK_OFFSET
> support"), there is a new instruction "sub.d $sp, $sp, $t0" for the
> secondary stack in do_syscall(), then there exists a objtool warning
> "do_syscall+0x11c: return with modified stack frame" and there is no
> handle_syscall() which is the previous frame of do_syscall() in the
> call trace when executing the command "echo l > /proc/sysrq-trigger".
>
> objdump shows something like this:
>
> 0000000000000000 <do_syscall>:
>     0:   02ff8063        addi.d          $sp, $sp, -32
>     4:   29c04076        st.d            $fp, $sp, 16
>     8:   29c02077        st.d            $s0, $sp, 8
>     c:   29c06061        st.d            $ra, $sp, 24
>    10:   02c08076        addi.d          $fp, $sp, 32
>    ...
>    74:   0011b063        sub.d           $sp, $sp, $t0
>    ...
>    a8:   4c000181        jirl            $ra, $t0, 0
>    ...
>    dc:   02ff82c3        addi.d          $sp, $fp, -32
>    e0:   28c06061        ld.d            $ra, $sp, 24
>    e4:   28c04076        ld.d            $fp, $sp, 16
>    e8:   28c02077        ld.d            $s0, $sp, 8
>    ec:   02c08063        addi.d          $sp, $sp, 32
>    f0:   4c000020        jirl            $zero, $ra, 0
>
> The instruction "sub.d $sp, $sp, $t0" changes the stack bottom
> and the new stack size is a random value, in order to find the
> return address of do_syscall() which is stored in the original
> stack frame after executing "jirl $ra, $t0, 0", it should use
> fp which points to the original stack top.
>
> This is a rare case, add a member "secondary_stack" in the struct
> symbol as a label to avoid affecting the current normal case, then
> set it as true only if there exists the secondary stack instruction
> "sub.d $sp, $sp, $t0", at last check this label for the other special
> secondary stack instructions about fp to change the cfa base and cfa
> offset during the period of secondary stack in update_cfi_state().
>
> Tested with the following two configs:
> (1) CONFIG_RANDOMIZE_KSTACK_OFFSET=y &&
>      CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=n
> (2) CONFIG_RANDOMIZE_KSTACK_OFFSET=y &&
>      CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y
>
> Cc: stable@vger.kernel.org # 6.9+
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>   tools/objtool/arch/loongarch/decode.c |  8 +++++++-
>   tools/objtool/check.c                 | 22 ++++++++++++++++++++++
>   tools/objtool/include/objtool/elf.h   |  1 +
>   3 files changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
> index db4dd05cdb49..4085714ffd18 100644
> --- a/tools/objtool/arch/loongarch/decode.c
> +++ b/tools/objtool/arch/loongarch/decode.c
> @@ -122,7 +122,7 @@ static bool decode_insn_reg2i12_fomat(union loongarch_instruction inst,
>   	switch (inst.reg2i12_format.opcode) {
>   	case addid_op:
>   		if ((inst.reg2i12_format.rd == CFI_SP) || (inst.reg2i12_format.rj == CFI_SP)) {
> -			/* addi.d sp,sp,si12 or addi.d fp,sp,si12 */
> +			/* addi.d sp,sp,si12 or addi.d fp,sp,si12 or addi.d sp,fp,si12 */
>   			insn->immediate = sign_extend64(inst.reg2i12_format.immediate, 11);
>   			ADD_OP(op) {
>   				op->src.type = OP_SRC_ADD;
> @@ -275,6 +275,8 @@ static bool decode_insn_reg2i16_fomat(union loongarch_instruction inst,
>   static bool decode_insn_reg3_fomat(union loongarch_instruction inst,
>   				   struct instruction *insn)
>   {
> +	struct symbol *func;
> +
>   	switch (inst.reg3_format.opcode) {
>   	case subd_op:
>   		if ((inst.reg3_format.rd == CFI_SP) && (inst.reg3_format.rj == CFI_SP)) {
> @@ -282,6 +284,10 @@ static bool decode_insn_reg3_fomat(union loongarch_instruction inst,
>   			 * sub.d sp,sp,t0
>   			 * this is a rare case for the secondary stack.
>   			 */
> +			func = find_func_containing(insn->sec, insn->offset);
> +			if (!func)
> +				return false;
> +			func->secondary_stack = true;
>   		}
>   		break;
>   	default:
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 01237d167223..c7b9942fee29 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -2993,6 +2993,28 @@ static int update_cfi_state(struct instruction *insn,
>   				break;
>   			}
>   
> +			if (op->dest.reg == CFI_BP && op->src.reg == CFI_SP) {
> +				/* addi.d fp,sp,imm for the secondary stack on LoongArch */
> +				if (cfa->base == CFI_SP && cfa->offset == op->src.offset) {
> +					if (insn->sym->secondary_stack) {
> +						cfa->base = CFI_BP;
> +						cfa->offset = 0;
> +					}
> +				}
> +				break;
> +			}
> +
> +			if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
> +				/* addi.d sp,fp,imm for the secondary stack on LoongArch */
> +				if (cfa->base == CFI_FP && cfa->offset == 0) {
> +					if (insn->sym->secondary_stack) {
> +						cfa->base = CFI_SP;
> +						cfa->offset = -op->src.offset;
> +					}
> +				}
> +				break;
> +			}
> +
>   			if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
>   
>   				/* lea disp(%rbp), %rsp */
> diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
> index 2b8a69de4db8..586916e0d441 100644
> --- a/tools/objtool/include/objtool/elf.h
> +++ b/tools/objtool/include/objtool/elf.h
> @@ -68,6 +68,7 @@ struct symbol {
>   	u8 warned	     : 1;
>   	u8 embedded_insn     : 1;
>   	u8 local_label       : 1;
> +	u8 secondary_stack   : 1;
>   	struct list_head pv_target;
>   	struct reloc *relocs;
>   };

LGTM although I think we should make update_cfi_state() arch-specific.
It also fix many warning when use Clang, thanks.

Jinyang

[PATCH v2 3/3] LoongArch: Remove STACK_FRAME_NON_STANDARD(do_syscall)

[Tiezhu Yang]

For now, it can remove STACK_FRAME_NON_STANDARD(do_syscall) because
there is no objtool warning "do_syscall+0x11c: return with modified
stack frame", then there is handle_syscall() which is the previous
frame of do_syscall() in the call trace when executing the command
"echo l > /proc/sysrq-trigger".

Fixes: a0f7085f6a63 ("LoongArch: Add RANDOMIZE_KSTACK_OFFSET support")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 arch/loongarch/kernel/syscall.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/loongarch/kernel/syscall.c b/arch/loongarch/kernel/syscall.c
index ba5d0930a74f..168bd97540f8 100644
--- a/arch/loongarch/kernel/syscall.c
+++ b/arch/loongarch/kernel/syscall.c
@@ -79,7 +79,3 @@ void noinstr __no_stack_protector do_syscall(struct pt_regs *regs)
 
 	syscall_exit_to_user_mode(regs);
 }
-
-#ifdef CONFIG_RANDOMIZE_KSTACK_OFFSET
-STACK_FRAME_NON_STANDARD(do_syscall);
-#endif
-- 
2.42.0