objtool errors and warnings with clang-21

["Arnd Bergmann" <arnd@arndb.de>]

Here is a list of issues I currently see with linux-next and llvm-21 from
https://apt.llvm.org/bookworm, along with the .config files:

https://pastebin.com/mRxkgudJ 
drivers/gpu/drm/vmwgfx/vmwgfx_msg.o: warning: objtool: vmw_host_printf+0xe: unknown CFA base reg 0
make[8]: *** [/home/arnd/arm-soc/scripts/Makefile.build:195: drivers/gpu/drm/vmwgfx/vmwgfx_msg.o] Error 255

https://pastebin.com/7XEcstHP
drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x17f: undefined stack state
drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x17c: unknown CFA base reg -1
make[7]: *** [/home/arnd/arm-soc/scripts/Makefile.build:195: drivers/input/misc/uinput.o] Error 255

https://pastebin.com/6wAzkUL5
vmlinux.o: warning: objtool: ___bpf_prog_run+0x208: sibling call from callable instruction with modified stack frame
vmlinux.o: warning: objtool: __ubsan_handle_type_mismatch+0xdb: call to __msan_memset() with UACCESS enabled
vmlinux.o: warning: objtool: __ubsan_handle_type_mismatch_v1+0xf8: call to __msan_memset() with UACCESS enabled

https://pastebin.com/PQZDZV18
fs/fat/dir.o: warning: objtool: fat_ioctl_filldir+0x717: stack state mismatch: cfa1=4+168 cfa2=4+160

https://pastebin.com/StQRVCfQ
sound/soc/codecs/snd-soc-wcd9335.o: warning: objtool: wcd9335_slimbus_irq() falls through to next function __cfi_wcd9335_set_channel_map()

and a bunch more fallthrough warnings that are likely all related to that one:

drivers/gpu/drm/amd/amdgpu/../display/dc/basics/fixpt31_32.o: warning: objtool: dc_fixpt_recip() falls through to next function __cfi_dc_fixpt_sinc()
drivers/gpu/drm/msm/msm.o: warning: objtool: msm_dp_catalog_ctrl_config_msa() falls through to next function msm_dp_catalog_ctrl_set_pattern_state_bit()
drivers/iio/imu/bmi160/bmi160_core.o: warning: objtool: bmi160_setup_irq() falls through to next function bmi160_data_rdy_trigger_set_state()
drivers/media/i2c/ccs/ccs-core.o: warning: objtool: ccs_set_selection() falls through to next function ccs_propagate()
sound/soc/codecs/aw88399.o: warning: objtool: aw_dev_dsp_update_cfg() falls through to next function aw_dev_get_int_status()

     Arnd