[PATCH v3 0/4] Fix objtool issues about do_syscall() and Clang 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".

Compiled with GCC and Clang, 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 (4):
  objtool: Handle frame pointer related instructions
  LoongArch: Remove STACK_FRAME_NON_STANDARD(do_syscall)
  LoongArch: Set AS_HAS_THIN_ADD_SUB as y if AS_IS_LLVM
  LoongArch: Enable objtool for Clang

 arch/loongarch/Kconfig                |  4 ++--
 arch/loongarch/kernel/syscall.c       |  4 ----
 tools/objtool/arch/loongarch/decode.c | 11 ++++++++++-
 tools/objtool/check.c                 | 23 ++++++++++++++++++++---
 tools/objtool/include/objtool/elf.h   |  1 +
 5 files changed, 33 insertions(+), 10 deletions(-)

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2.42.0