[PATCH 00/12] Sprinkle more __noreturn

[PATCH 00/12] Sprinkle more __noreturn

[Josh Poimboeuf]

Add some more __noreturn annotations.

Many of these have been flushed out by kernel IBT support which made
objtool vmlinux validation much more common.

These annotations are generally a good thing as they improve readability
and code generation.


Guilherme G. Piccoli (1):
  x86/hyperv: Mark hv_ghcb_terminate() as noreturn

Josh Poimboeuf (10):
  init: Mark [arch_call_]rest_init() __noreturn
  init: Mark start_kernel() __noreturn
  x86/head: Mark *_start_kernel() __noreturn
  btrfs: Mark btrfs_assertfail() __noreturn
  arm64/cpu: Mark cpu_park_loop() and friends __noreturn
  cpu: Mark panic_smp_self_stop() __noreturn
  cpu: Mark nmi_panic_self_stop() __noreturn
  x86/cpu: Mark {hlt,resume}_play_dead() __noreturn
  objtool: Include weak functions in global_noreturns check
  scsi: message: fusion: Mark mpt_halt_firmware() __noreturn

 arch/arm/kernel/smp.c              |  2 +-
 arch/arm64/include/asm/exception.h |  2 +-
 arch/arm64/include/asm/smp.h       |  7 +++----
 arch/arm64/kernel/entry-common.c   |  2 +-
 arch/arm64/kernel/smp.c            | 10 ++++++----
 arch/arm64/kernel/traps.c          |  3 +--
 arch/powerpc/kernel/setup_64.c     |  2 +-
 arch/s390/kernel/setup.c           |  2 +-
 arch/x86/hyperv/ivm.c              |  2 +-
 arch/x86/include/asm/mshyperv.h    |  2 +-
 arch/x86/include/asm/reboot.h      |  1 -
 arch/x86/include/asm/setup.h       |  6 +++---
 arch/x86/include/asm/smp.h         |  2 +-
 arch/x86/kernel/head32.c           |  2 +-
 arch/x86/kernel/head64.c           |  4 ++--
 arch/x86/kernel/reboot.c           |  2 +-
 arch/x86/kernel/smpboot.c          |  2 +-
 arch/x86/power/cpu.c               |  2 +-
 drivers/message/fusion/mptbase.c   |  2 +-
 drivers/message/fusion/mptbase.h   |  2 +-
 fs/btrfs/messages.c                |  2 +-
 fs/btrfs/messages.h                |  2 +-
 include/linux/smp.h                |  4 ++--
 include/linux/start_kernel.h       |  6 +++---
 init/main.c                        |  6 +++---
 kernel/panic.c                     |  4 ++--
 tools/objtool/check.c              | 20 ++++++++++++++++----
 27 files changed, 57 insertions(+), 46 deletions(-)

-- 
2.39.2

[PATCH 01/11] init: Mark [arch_call_]rest_init() __noreturn

[Josh Poimboeuf]

Fixes the following warning:

  init/main.o: warning: objtool: start_kernel+0x4ad: unreachable instruction

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/s390/kernel/setup.c     | 2 +-
 include/linux/start_kernel.h | 4 ++--
 init/main.c                  | 4 ++--
 tools/objtool/check.c        | 2 ++
 4 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 8ec5cdf9dadc..4259b6c50516 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -396,7 +396,7 @@ int __init arch_early_irq_init(void)
 	return 0;
 }
 
-void __init arch_call_rest_init(void)
+void __init __noreturn arch_call_rest_init(void)
 {
 	unsigned long stack;
 
diff --git a/include/linux/start_kernel.h b/include/linux/start_kernel.h
index 8b369a41c03c..864921e54c92 100644
--- a/include/linux/start_kernel.h
+++ b/include/linux/start_kernel.h
@@ -9,7 +9,7 @@
    up something else. */
 
 extern asmlinkage void __init start_kernel(void);
-extern void __init arch_call_rest_init(void);
-extern void __ref rest_init(void);
+extern void __init __noreturn arch_call_rest_init(void);
+extern void __ref __noreturn rest_init(void);
 
 #endif /* _LINUX_START_KERNEL_H */
diff --git a/init/main.c b/init/main.c
index 4425d1783d5c..161ed956d738 100644
--- a/init/main.c
+++ b/init/main.c
@@ -683,7 +683,7 @@ static void __init setup_command_line(char *command_line)
 
 static __initdata DECLARE_COMPLETION(kthreadd_done);
 
-noinline void __ref rest_init(void)
+noinline void __ref __noreturn rest_init(void)
 {
 	struct task_struct *tsk;
 	int pid;
@@ -889,7 +889,7 @@ static int __init early_randomize_kstack_offset(char *buf)
 early_param("randomize_kstack_offset", early_randomize_kstack_offset);
 #endif
 
-void __init __weak arch_call_rest_init(void)
+void __init __weak __noreturn arch_call_rest_init(void)
 {
 	rest_init();
 }
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index cae6ac6ff246..e7442e7ad676 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -202,6 +202,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"__reiserfs_panic",
 		"__stack_chk_fail",
 		"__ubsan_handle_builtin_unreachable",
+		"arch_call_rest_init",
 		"arch_cpu_idle_dead",
 		"cpu_bringup_and_idle",
 		"cpu_startup_entry",
@@ -217,6 +218,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"machine_real_restart",
 		"make_task_dead",
 		"panic",
+		"rest_init",
 		"rewind_stack_and_make_dead",
 		"sev_es_terminate",
 		"snp_abort",
-- 
2.39.2

Re: [PATCH 01/11] init: Mark [arch_call_]rest_init() __noreturn

[Nick Desaulniers]

On Fri, Apr 07, 2023 at 05:09:54PM -0700, Josh Poimboeuf wrote:
> Fixes the following warning:
> 
>   init/main.o: warning: objtool: start_kernel+0x4ad: unreachable instruction
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

Ha! I was just looking into this, by coincidence.
https://github.com/ClangBuiltLinux/linux/issues/1815#issuecomment-1489113303

Generally, the compiler can infer when a function does not return, but
it's not safe to do so when the definition is weak, since the strong
definition may not be, so the caller must not make optimizations based
on such an assumption.

https://reviews.llvm.org/D147177 (abandoned, but has more info)

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

(I agree with the first two patches, since those are ones I was just
looking at.  Unfortunately, some security embargo just lifted on
https://bugs.chromium.org/p/llvm/issues/detail?id=30 which a clang-16
change is causing the stack canaries to be set+checked again in
start_kernel. I'm about to meet with LLVM folks at Intel in 30 minutes
to discuss walking back some of the changes since I strongly disagree
with them.  But merging this series will cause boot failures with
clang-16, and I would appreciate some time to sort this out before this
series is merged. It's my top priority.)

> ---
>  arch/s390/kernel/setup.c     | 2 +-
>  include/linux/start_kernel.h | 4 ++--
>  init/main.c                  | 4 ++--
>  tools/objtool/check.c        | 2 ++
>  4 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
> index 8ec5cdf9dadc..4259b6c50516 100644
> --- a/arch/s390/kernel/setup.c
> +++ b/arch/s390/kernel/setup.c
> @@ -396,7 +396,7 @@ int __init arch_early_irq_init(void)
>  	return 0;
>  }
>  
> -void __init arch_call_rest_init(void)
> +void __init __noreturn arch_call_rest_init(void)
>  {
>  	unsigned long stack;
>  
> diff --git a/include/linux/start_kernel.h b/include/linux/start_kernel.h
> index 8b369a41c03c..864921e54c92 100644
> --- a/include/linux/start_kernel.h
> +++ b/include/linux/start_kernel.h
> @@ -9,7 +9,7 @@
>     up something else. */
>  
>  extern asmlinkage void __init start_kernel(void);
> -extern void __init arch_call_rest_init(void);
> -extern void __ref rest_init(void);
> +extern void __init __noreturn arch_call_rest_init(void);
> +extern void __ref __noreturn rest_init(void);
>  
>  #endif /* _LINUX_START_KERNEL_H */
> diff --git a/init/main.c b/init/main.c
> index 4425d1783d5c..161ed956d738 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -683,7 +683,7 @@ static void __init setup_command_line(char *command_line)
>  
>  static __initdata DECLARE_COMPLETION(kthreadd_done);
>  
> -noinline void __ref rest_init(void)
> +noinline void __ref __noreturn rest_init(void)
>  {
>  	struct task_struct *tsk;
>  	int pid;
> @@ -889,7 +889,7 @@ static int __init early_randomize_kstack_offset(char *buf)
>  early_param("randomize_kstack_offset", early_randomize_kstack_offset);
>  #endif
>  
> -void __init __weak arch_call_rest_init(void)
> +void __init __weak __noreturn arch_call_rest_init(void)
>  {
>  	rest_init();
>  }
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index cae6ac6ff246..e7442e7ad676 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -202,6 +202,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
>  		"__reiserfs_panic",
>  		"__stack_chk_fail",
>  		"__ubsan_handle_builtin_unreachable",
> +		"arch_call_rest_init",
>  		"arch_cpu_idle_dead",
>  		"cpu_bringup_and_idle",
>  		"cpu_startup_entry",
> @@ -217,6 +218,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
>  		"machine_real_restart",
>  		"make_task_dead",
>  		"panic",
> +		"rest_init",
>  		"rewind_stack_and_make_dead",
>  		"sev_es_terminate",
>  		"snp_abort",
> -- 
> 2.39.2
> 
> 

[PATCH 02/11] init: Mark start_kernel() __noreturn

[Josh Poimboeuf]

Fixes the following warning:

  vmlinux.o: warning: objtool: x86_64_start_reservations+0x28: unreachable instruction

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/202302161142.K3ziREaj-lkp@intel.com/
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 include/linux/start_kernel.h | 2 +-
 init/main.c                  | 2 +-
 tools/objtool/check.c        | 1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/start_kernel.h b/include/linux/start_kernel.h
index 864921e54c92..a9806a44a605 100644
--- a/include/linux/start_kernel.h
+++ b/include/linux/start_kernel.h
@@ -8,7 +8,7 @@
 /* Define the prototype for start_kernel here, rather than cluttering
    up something else. */
 
-extern asmlinkage void __init start_kernel(void);
+extern asmlinkage void __init __noreturn start_kernel(void);
 extern void __init __noreturn arch_call_rest_init(void);
 extern void __ref __noreturn rest_init(void);
 
diff --git a/init/main.c b/init/main.c
index 161ed956d738..65aab4e9bb49 100644
--- a/init/main.c
+++ b/init/main.c
@@ -937,7 +937,7 @@ static void __init print_unknown_bootoptions(void)
 	memblock_free(unknown_options, len);
 }
 
-asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
+asmlinkage __visible void __init __no_sanitize_address __noreturn start_kernel(void)
 {
 	char *command_line;
 	char *after_dashes;
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index e7442e7ad676..a6f9a4aeb77b 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -222,6 +222,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"rewind_stack_and_make_dead",
 		"sev_es_terminate",
 		"snp_abort",
+		"start_kernel",
 		"stop_this_cpu",
 		"usercopy_abort",
 		"xen_cpu_bringup_again",
-- 
2.39.2

Re: [PATCH 02/11] init: Mark start_kernel() __noreturn

[Nick Desaulniers]

On Fri, Apr 07, 2023 at 05:09:55PM -0700, Josh Poimboeuf wrote:
> Fixes the following warning:
> 
>   vmlinux.o: warning: objtool: x86_64_start_reservations+0x28: unreachable instruction
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Link: https://lore.kernel.org/r/202302161142.K3ziREaj-lkp@intel.com/
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

Ah, I just realized that my series will conflict with this.
https://lore.kernel.org/llvm/20230412-no_stackp-v1-1-46a69b507a4b@google.com/
Perhaps if my series gets positive feedback; I can rebase it on top of
this and it can become part of your series?

For this patch,
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

Though I'm curious, it does look like it's necessary because of 01/11 in
the series? Any idea how the 0day bot report happened before 1/11
existed?

(Surely gcc isn't assuming a weak function is implicitly noreturn and
make optimizations based on that (that's one hazard I'm worried about)?)

It looks like perhaps the link to
https://lore.kernel.org/all/202302161142.K3ziREaj-lkp@intel.com/
on 2/11 was 0day testing the arch-cpu-idle-dead-noreturn branch of your
kernel tree
https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/log/?h=arch-cpu-idle-dead-noreturn
, which had 1/11 in it, IIUC?  Perhaps this link should go on 1/11
rather than 2/11?

Looking back at 1/11, 3/11, 8/11 I noticed not all patches have links to 0day
reports.  Are you able to flesh out more info how/what/when such objtool
warnings are observed?  Are the warnings ever results of patches earlier
in the series?

Re: [PATCH 02/11] init: Mark start_kernel() __noreturn

[Josh Poimboeuf]

On Wed, Apr 12, 2023 at 01:29:49PM -0700, Nick Desaulniers wrote:
> On Fri, Apr 07, 2023 at 05:09:55PM -0700, Josh Poimboeuf wrote:
> > Fixes the following warning:
> > 
> >   vmlinux.o: warning: objtool: x86_64_start_reservations+0x28: unreachable instruction
> > 
> > Reported-by: kernel test robot <lkp@intel.com>
> > Link: https://lore.kernel.org/r/202302161142.K3ziREaj-lkp@intel.com/
> > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> 
> Ah, I just realized that my series will conflict with this.
> https://lore.kernel.org/llvm/20230412-no_stackp-v1-1-46a69b507a4b@google.com/
> Perhaps if my series gets positive feedback; I can rebase it on top of
> this and it can become part of your series?

Sure, I can take these on top.

> For this patch,
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

Thanks!

> Though I'm curious, it does look like it's necessary because of 01/11 in
> the series? Any idea how the 0day bot report happened before 1/11
> existed?
>
> 
> (Surely gcc isn't assuming a weak function is implicitly noreturn and
> make optimizations based on that (that's one hazard I'm worried about)?)

As far as I can tell, GCC has been doing the right thing here, and it's
instead been objtool getting confused by weak noreturns.  That gets
fixed later in patch 9.

> It looks like perhaps the link to
> https://lore.kernel.org/all/202302161142.K3ziREaj-lkp@intel.com/
> on 2/11 was 0day testing the arch-cpu-idle-dead-noreturn branch of your
> kernel tree
> https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/log/?h=arch-cpu-idle-dead-noreturn
> , which had 1/11 in it, IIUC?  Perhaps this link should go on 1/11
> rather than 2/11?

Good catch, patch 1 does introduce the warning.  I think I'll just
squash patches 1 and 2 so as not to break bisection.

> Looking back at 1/11, 3/11, 8/11 I noticed not all patches have links to 0day
> reports.  Are you able to flesh out more info how/what/when such objtool
> warnings are observed?  Are the warnings ever results of patches earlier
> in the series?

Hopefully not, it's best to not introduce warnings even temporarily.  I
was doing a lot of build testing at the time with various branches, so
it's possible.  I'll see if I can figure out how I triggered those
warnings and document that in the commit logs if possible.

-- 
Josh

Re: [PATCH 02/11] init: Mark start_kernel() __noreturn

[Josh Poimboeuf]

On Wed, Apr 12, 2023 at 02:57:57PM -0700, Josh Poimboeuf wrote:
> > It looks like perhaps the link to
> > https://lore.kernel.org/all/202302161142.K3ziREaj-lkp@intel.com/
> > on 2/11 was 0day testing the arch-cpu-idle-dead-noreturn branch of your
> > kernel tree
> > https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/log/?h=arch-cpu-idle-dead-noreturn
> > , which had 1/11 in it, IIUC?  Perhaps this link should go on 1/11
> > rather than 2/11?
> 
> Good catch, patch 1 does introduce the warning.  I think I'll just
> squash patches 1 and 2 so as not to break bisection.
> 
> > Looking back at 1/11, 3/11, 8/11 I noticed not all patches have links to 0day
> > reports.  Are you able to flesh out more info how/what/when such objtool
> > warnings are observed?  Are the warnings ever results of patches earlier
> > in the series?
> 
> Hopefully not, it's best to not introduce warnings even temporarily.  I
> was doing a lot of build testing at the time with various branches, so
> it's possible.  I'll see if I can figure out how I triggered those
> warnings and document that in the commit logs if possible.

On second thought I won't squash, keeping them separate is useful for
both patches 1 & 2 and patches 5-7.  The patch order goes up the call
stack, i.e. fix callees before callers.  The opposite order would
trigger actual compiler warnings rather than measly objtool warnings :-)

I agree some of the commit logs are indeed confusing and sometimes even
wrong.  I'll clarify the justifications, and remove references to build
bot warnings if they apply to previous patches in the set.

-- 
Josh

[PATCH 03/11] x86/head: Mark *_start_kernel() __noreturn

[Josh Poimboeuf]

Fixes the following warning:

  vmlinux.o: warning: objtool: resume_play_dead+0x21: unreachable instruction

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/x86/include/asm/setup.h | 6 +++---
 arch/x86/kernel/head32.c     | 2 +-
 arch/x86/kernel/head64.c     | 4 ++--
 tools/objtool/check.c        | 2 ++
 4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index f37cbff7354c..f3495623ac99 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -125,11 +125,11 @@ void clear_bss(void);
 
 #ifdef __i386__
 
-asmlinkage void __init i386_start_kernel(void);
+asmlinkage void __init __noreturn i386_start_kernel(void);
 
 #else
-asmlinkage void __init x86_64_start_kernel(char *real_mode);
-asmlinkage void __init x86_64_start_reservations(char *real_mode_data);
+asmlinkage void __init __noreturn x86_64_start_kernel(char *real_mode);
+asmlinkage void __init __noreturn x86_64_start_reservations(char *real_mode_data);
 
 #endif /* __i386__ */
 #endif /* _SETUP */
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index ec6fefbfd3c0..10c27b4261eb 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -29,7 +29,7 @@ static void __init i386_default_early_setup(void)
 	x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
 }
 
-asmlinkage __visible void __init i386_start_kernel(void)
+asmlinkage __visible void __init __noreturn i386_start_kernel(void)
 {
 	/* Make sure IDT is set up before any exception happens */
 	idt_setup_early_handler();
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 387e4b12e823..49f7629b17f7 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -471,7 +471,7 @@ static void __init copy_bootdata(char *real_mode_data)
 	sme_unmap_bootdata(real_mode_data);
 }
 
-asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
+asmlinkage __visible void __init __noreturn x86_64_start_kernel(char * real_mode_data)
 {
 	/*
 	 * Build-time sanity checks on the kernel image and module
@@ -537,7 +537,7 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 	x86_64_start_reservations(real_mode_data);
 }
 
-void __init x86_64_start_reservations(char *real_mode_data)
+void __init __noreturn x86_64_start_reservations(char *real_mode_data)
 {
 	/* version is always not zero if it is copied */
 	if (!boot_params.hdr.version)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a6f9a4aeb77b..4e89342dd8fb 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -225,6 +225,8 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"start_kernel",
 		"stop_this_cpu",
 		"usercopy_abort",
+		"x86_64_start_kernel",
+		"x86_64_start_reservations",
 		"xen_cpu_bringup_again",
 		"xen_start_kernel",
 	};
-- 
2.39.2

[PATCH 04/11] btrfs: Mark btrfs_assertfail() __noreturn

[Josh Poimboeuf]

Fixes a bunch of warnings including:

  vmlinux.o: warning: objtool: select_reloc_root+0x314: unreachable instruction
  vmlinux.o: warning: objtool: finish_inode_if_needed+0x15b1: unreachable instruction
  vmlinux.o: warning: objtool: get_bio_sector_nr+0x259: unreachable instruction
  vmlinux.o: warning: objtool: raid_wait_read_end_io+0xc26: unreachable instruction
  vmlinux.o: warning: objtool: raid56_parity_alloc_scrub_rbio+0x37b: unreachable instruction
  ...

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202302210709.IlXfgMpX-lkp@intel.com/
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 fs/btrfs/messages.c   | 2 +-
 fs/btrfs/messages.h   | 2 +-
 tools/objtool/check.c | 1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/messages.c b/fs/btrfs/messages.c
index fde5aaa6e7c9..310a05cf95ef 100644
--- a/fs/btrfs/messages.c
+++ b/fs/btrfs/messages.c
@@ -253,7 +253,7 @@ void __cold _btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt,
 #endif
 
 #ifdef CONFIG_BTRFS_ASSERT
-void __cold btrfs_assertfail(const char *expr, const char *file, int line)
+void __cold __noreturn btrfs_assertfail(const char *expr, const char *file, int line)
 {
 	pr_err("assertion failed: %s, in %s:%d\n", expr, file, line);
 	BUG();
diff --git a/fs/btrfs/messages.h b/fs/btrfs/messages.h
index 8c516ee58ff9..ac2d1982ba3d 100644
--- a/fs/btrfs/messages.h
+++ b/fs/btrfs/messages.h
@@ -160,7 +160,7 @@ do {								\
 } while (0)
 
 #ifdef CONFIG_BTRFS_ASSERT
-void __cold btrfs_assertfail(const char *expr, const char *file, int line);
+void __cold __noreturn btrfs_assertfail(const char *expr, const char *file, int line);
 
 #define ASSERT(expr)						\
 	(likely(expr) ? (void)0 : btrfs_assertfail(#expr, __FILE__, __LINE__))
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4e89342dd8fb..a8714d62074e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -204,6 +204,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"__ubsan_handle_builtin_unreachable",
 		"arch_call_rest_init",
 		"arch_cpu_idle_dead",
+		"btrfs_assertfail",
 		"cpu_bringup_and_idle",
 		"cpu_startup_entry",
 		"do_exit",
-- 
2.39.2

[PATCH 05/11] arm64/cpu: Mark cpu_park_loop() and friends __noreturn

[Josh Poimboeuf]

In preparation for marking panic_smp_self_stop() __noreturn across the
kernel, first mark the arm64 implementation of cpu_park_loop() and
related functions __noreturn.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/arm64/include/asm/exception.h | 2 +-
 arch/arm64/include/asm/smp.h       | 6 +++---
 arch/arm64/kernel/entry-common.c   | 2 +-
 arch/arm64/kernel/smp.c            | 8 +++++---
 arch/arm64/kernel/traps.c          | 3 +--
 5 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
index 92963f98afec..01b5b99c6c66 100644
--- a/arch/arm64/include/asm/exception.h
+++ b/arch/arm64/include/asm/exception.h
@@ -80,5 +80,5 @@ void do_el1_fpac(struct pt_regs *regs, unsigned long esr);
 void do_serror(struct pt_regs *regs, unsigned long esr);
 void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags);
 
-void panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far);
+void __noreturn panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far);
 #endif	/* __ASM_EXCEPTION_H */
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 5733a31bab08..07f4ea1490f4 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -101,9 +101,9 @@ extern int __cpu_disable(void);
 
 extern void __cpu_die(unsigned int cpu);
 extern void __noreturn cpu_die(void);
-extern void cpu_die_early(void);
+extern void __noreturn cpu_die_early(void);
 
-static inline void cpu_park_loop(void)
+static inline void __noreturn cpu_park_loop(void)
 {
 	for (;;) {
 		wfe();
@@ -123,7 +123,7 @@ static inline void update_cpu_boot_status(int val)
  * which calls for a kernel panic. Update the boot status and park the calling
  * CPU.
  */
-static inline void cpu_panic_kernel(void)
+static inline void __noreturn cpu_panic_kernel(void)
 {
 	update_cpu_boot_status(CPU_PANIC_KERNEL);
 	cpu_park_loop();
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index cce1167199e3..3af3c01c93a6 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -840,7 +840,7 @@ UNHANDLED(el0t, 32, error)
 #endif /* CONFIG_COMPAT */
 
 #ifdef CONFIG_VMAP_STACK
-asmlinkage void noinstr handle_bad_stack(struct pt_regs *regs)
+asmlinkage void noinstr __noreturn handle_bad_stack(struct pt_regs *regs)
 {
 	unsigned long esr = read_sysreg(esr_el1);
 	unsigned long far = read_sysreg(far_el1);
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index d5d09a18b4f8..07d156fddb5f 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -398,7 +398,7 @@ static void __cpu_try_die(int cpu)
  * Kill the calling secondary CPU, early in bringup before it is turned
  * online.
  */
-void cpu_die_early(void)
+void __noreturn cpu_die_early(void)
 {
 	int cpu = smp_processor_id();
 
@@ -816,7 +816,7 @@ void arch_irq_work_raise(void)
 }
 #endif
 
-static void local_cpu_stop(void)
+static void __noreturn local_cpu_stop(void)
 {
 	set_cpu_online(smp_processor_id(), false);
 
@@ -839,7 +839,7 @@ void panic_smp_self_stop(void)
 static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
 #endif
 
-static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
+static void __noreturn ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
 {
 #ifdef CONFIG_KEXEC_CORE
 	crash_save_cpu(regs, cpu);
@@ -854,6 +854,8 @@ static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
 
 	/* just in case */
 	cpu_park_loop();
+#else
+	BUG();
 #endif
 }
 
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 4a79ba100799..4bb1b8f47298 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -863,7 +863,7 @@ void bad_el0_sync(struct pt_regs *regs, int reason, unsigned long esr)
 DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack)
 	__aligned(16);
 
-void panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far)
+void __noreturn panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far)
 {
 	unsigned long tsk_stk = (unsigned long)current->stack;
 	unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr);
@@ -905,7 +905,6 @@ void __noreturn arm64_serror_panic(struct pt_regs *regs, unsigned long esr)
 	nmi_panic(regs, "Asynchronous SError Interrupt");
 
 	cpu_park_loop();
-	unreachable();
 }
 
 bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned long esr)
-- 
2.39.2

[PATCH 06/11] cpu: Mark panic_smp_self_stop() __noreturn

[Josh Poimboeuf]

panic_smp_self_stop() doesn't return.  Annotate it as such.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/arm/kernel/smp.c          | 2 +-
 arch/arm64/include/asm/smp.h   | 1 -
 arch/arm64/kernel/smp.c        | 2 +-
 arch/powerpc/kernel/setup_64.c | 2 +-
 include/linux/smp.h            | 2 +-
 kernel/panic.c                 | 2 +-
 tools/objtool/check.c          | 1 +
 7 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index d6be4507d22d..f4a4ac028b6b 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -779,7 +779,7 @@ void smp_send_stop(void)
  * kdump fails. So split out the panic_smp_self_stop() and add
  * set_cpu_online(smp_processor_id(), false).
  */
-void panic_smp_self_stop(void)
+void __noreturn panic_smp_self_stop(void)
 {
 	pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 	         smp_processor_id());
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 07f4ea1490f4..f2d26235bfb4 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -143,7 +143,6 @@ bool cpus_are_stuck_in_kernel(void);
 
 extern void crash_smp_send_stop(void);
 extern bool smp_crash_stop_failed(void);
-extern void panic_smp_self_stop(void);
 
 #endif /* ifndef __ASSEMBLY__ */
 
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 07d156fddb5f..05fe797e4203 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -830,7 +830,7 @@ static void __noreturn local_cpu_stop(void)
  * that cpu_online_mask gets correctly updated and smp_send_stop() can skip
  * CPUs that have already stopped themselves.
  */
-void panic_smp_self_stop(void)
+void __noreturn panic_smp_self_stop(void)
 {
 	local_cpu_stop();
 }
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index b2e0d3ce4261..246201d0d879 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -480,7 +480,7 @@ void early_setup_secondary(void)
 
 #endif /* CONFIG_SMP */
 
-void panic_smp_self_stop(void)
+void __noreturn panic_smp_self_stop(void)
 {
 	hard_irq_disable();
 	spin_begin();
diff --git a/include/linux/smp.h b/include/linux/smp.h
index a80ab58ae3f1..2a737b39cf0a 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -59,7 +59,7 @@ int smp_call_function_single_async(int cpu, struct __call_single_data *csd);
  * Cpus stopping functions in panic. All have default weak definitions.
  * Architecture-dependent code may override them.
  */
-void panic_smp_self_stop(void);
+void __noreturn panic_smp_self_stop(void);
 void nmi_panic_self_stop(struct pt_regs *regs);
 void crash_smp_send_stop(void);
 
diff --git a/kernel/panic.c b/kernel/panic.c
index 5cfea8302d23..5e4982db8dc9 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -141,7 +141,7 @@ EXPORT_SYMBOL(panic_blink);
 /*
  * Stop ourself in panic -- architecture code may override this
  */
-void __weak panic_smp_self_stop(void)
+void __weak __noreturn panic_smp_self_stop(void)
 {
 	while (1)
 		cpu_relax();
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a8714d62074e..3d0531f5e491 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -219,6 +219,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"machine_real_restart",
 		"make_task_dead",
 		"panic",
+		"panic_smp_self_stop",
 		"rest_init",
 		"rewind_stack_and_make_dead",
 		"sev_es_terminate",
-- 
2.39.2

[PATCH 07/11] cpu: Mark nmi_panic_self_stop() __noreturn

[Josh Poimboeuf]

nmi_panic_self_stop() doesn't return.  Annotate it as such.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/x86/include/asm/reboot.h | 1 -
 arch/x86/kernel/reboot.c      | 2 +-
 include/linux/smp.h           | 2 +-
 kernel/panic.c                | 2 +-
 tools/objtool/check.c         | 1 +
 5 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/reboot.h b/arch/x86/include/asm/reboot.h
index bc5b4d788c08..9177b4354c3f 100644
--- a/arch/x86/include/asm/reboot.h
+++ b/arch/x86/include/asm/reboot.h
@@ -28,7 +28,6 @@ void __noreturn machine_real_restart(unsigned int type);
 void cpu_emergency_disable_virtualization(void);
 
 typedef void (*nmi_shootdown_cb)(int, struct pt_regs*);
-void nmi_panic_self_stop(struct pt_regs *regs);
 void nmi_shootdown_cpus(nmi_shootdown_cb callback);
 void run_crash_ipi_callback(struct pt_regs *regs);
 
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index d03c551defcc..3adbe97015c1 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -920,7 +920,7 @@ void run_crash_ipi_callback(struct pt_regs *regs)
 }
 
 /* Override the weak function in kernel/panic.c */
-void nmi_panic_self_stop(struct pt_regs *regs)
+void __noreturn nmi_panic_self_stop(struct pt_regs *regs)
 {
 	while (1) {
 		/* If no CPU is preparing crash dump, we simply loop here. */
diff --git a/include/linux/smp.h b/include/linux/smp.h
index 2a737b39cf0a..7b93504eed26 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -60,7 +60,7 @@ int smp_call_function_single_async(int cpu, struct __call_single_data *csd);
  * Architecture-dependent code may override them.
  */
 void __noreturn panic_smp_self_stop(void);
-void nmi_panic_self_stop(struct pt_regs *regs);
+void __noreturn nmi_panic_self_stop(struct pt_regs *regs);
 void crash_smp_send_stop(void);
 
 /*
diff --git a/kernel/panic.c b/kernel/panic.c
index 5e4982db8dc9..886d2ebd0a0d 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -151,7 +151,7 @@ void __weak __noreturn panic_smp_self_stop(void)
  * Stop ourselves in NMI context if another CPU has already panicked. Arch code
  * may override this to prepare for crash dumping, e.g. save regs info.
  */
-void __weak nmi_panic_self_stop(struct pt_regs *regs)
+void __weak __noreturn nmi_panic_self_stop(struct pt_regs *regs)
 {
 	panic_smp_self_stop();
 }
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 3d0531f5e491..c5621dd866e1 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -218,6 +218,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"lbug_with_loc",
 		"machine_real_restart",
 		"make_task_dead",
+		"nmi_panic_self_stop",
 		"panic",
 		"panic_smp_self_stop",
 		"rest_init",
-- 
2.39.2

[PATCH 08/11] x86/cpu: Mark {hlt,resume}_play_dead() __noreturn

[Josh Poimboeuf]

Fixes the following warning:

  vmlinux.o: warning: objtool: resume_play_dead+0x21: unreachable instruction

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/x86/include/asm/smp.h | 2 +-
 arch/x86/kernel/smpboot.c  | 2 +-
 arch/x86/power/cpu.c       | 2 +-
 tools/objtool/check.c      | 2 ++
 4 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index e6d1d2810e38..47ce4c79a3b0 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -125,7 +125,7 @@ int native_cpu_up(unsigned int cpunum, struct task_struct *tidle);
 int native_cpu_disable(void);
 int common_cpu_die(unsigned int cpu);
 void native_cpu_die(unsigned int cpu);
-void hlt_play_dead(void);
+void __noreturn hlt_play_dead(void);
 void native_play_dead(void);
 void play_dead_common(void);
 void wbinvd_on_cpu(int cpu);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9013bb28255a..a6da3f94b7b6 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1816,7 +1816,7 @@ static inline void mwait_play_dead(void)
 	}
 }
 
-void hlt_play_dead(void)
+void __noreturn hlt_play_dead(void)
 {
 	if (__this_cpu_read(cpu_info.x86) >= 4)
 		wbinvd();
diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index 236447ee9beb..7a4d5e911415 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -288,7 +288,7 @@ EXPORT_SYMBOL(restore_processor_state);
 #endif
 
 #if defined(CONFIG_HIBERNATION) && defined(CONFIG_HOTPLUG_CPU)
-static void resume_play_dead(void)
+static void __noreturn resume_play_dead(void)
 {
 	play_dead_common();
 	tboot_shutdown(TB_SHUTDOWN_WFS);
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c5621dd866e1..a926da218c01 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -212,6 +212,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"do_task_dead",
 		"ex_handler_msr_mce",
 		"fortify_panic",
+		"hlt_play_dead",
 		"kthread_complete_and_exit",
 		"kthread_exit",
 		"kunit_try_catch_throw",
@@ -222,6 +223,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"panic",
 		"panic_smp_self_stop",
 		"rest_init",
+		"resume_play_dead",
 		"rewind_stack_and_make_dead",
 		"sev_es_terminate",
 		"snp_abort",
-- 
2.39.2

[PATCH 09/11] objtool: Include weak functions in global_noreturns check

[Josh Poimboeuf]

If a global function doesn't return, and its prototype has the
__noreturn attribute, its weak counterpart must also not return so that
it matches the prototype and meets call site expectations.

To properly follow the compiled control flow at the call sites, change
the global_noreturns check to include both global and weak functions.

On the other hand, if a weak function isn't in global_noreturns, assume
the prototype doesn't have __noreturn.  Even if the weak function
doesn't return, call sites treat it like a returnable function.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a926da218c01..a42a2af99ea2 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -239,14 +239,14 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 	if (!func)
 		return false;
 
-	if (func->bind == STB_WEAK)
-		return false;
-
-	if (func->bind == STB_GLOBAL)
+	if (func->bind == STB_GLOBAL || func->bind == STB_WEAK)
 		for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
 			if (!strcmp(func->name, global_noreturns[i]))
 				return true;
 
+	if (func->bind == STB_WEAK)
+		return false;
+
 	if (!func->len)
 		return false;
 
-- 
2.39.2

[PATCH 10/11] scsi: message: fusion: Mark mpt_halt_firmware() __noreturn

[Josh Poimboeuf]

mpt_halt_firmware() doesn't return.  Mark it as such.

Fixes the following warnings:

  vmlinux.o: warning: objtool: mptscsih_abort+0x7f4: unreachable instruction
  vmlinux.o: warning: objtool: mptctl_timeout_expired+0x310: unreachable instruction

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202302271743.78emit6I-lkp@intel.com/
Reported-by: Mark Rutland <mark.rutland@arm.com>
Debugged-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 drivers/message/fusion/mptbase.c | 2 +-
 drivers/message/fusion/mptbase.h | 2 +-
 tools/objtool/check.c            | 1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/message/fusion/mptbase.c b/drivers/message/fusion/mptbase.c
index 9b3ba2df71c7..4f0afce8428d 100644
--- a/drivers/message/fusion/mptbase.c
+++ b/drivers/message/fusion/mptbase.c
@@ -6935,7 +6935,7 @@ EXPORT_SYMBOL(mpt_clear_taskmgmt_in_progress_flag);
  *	@ioc: Pointer to MPT_ADAPTER structure
  *
  **/
-void
+void __noreturn
 mpt_halt_firmware(MPT_ADAPTER *ioc)
 {
 	u32	 ioc_raw_state;
diff --git a/drivers/message/fusion/mptbase.h b/drivers/message/fusion/mptbase.h
index 4bd0682c65d3..0f226cdad64f 100644
--- a/drivers/message/fusion/mptbase.h
+++ b/drivers/message/fusion/mptbase.h
@@ -945,7 +945,7 @@ extern int	mpt_raid_phys_disk_get_num_paths(MPT_ADAPTER *ioc,
 		u8 phys_disk_num);
 extern int	 mpt_set_taskmgmt_in_progress_flag(MPT_ADAPTER *ioc);
 extern void	 mpt_clear_taskmgmt_in_progress_flag(MPT_ADAPTER *ioc);
-extern void     mpt_halt_firmware(MPT_ADAPTER *ioc);
+extern void __noreturn mpt_halt_firmware(MPT_ADAPTER *ioc);
 
 
 /*
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a42a2af99ea2..8586d4c36600 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -219,6 +219,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"lbug_with_loc",
 		"machine_real_restart",
 		"make_task_dead",
+		"mpt_halt_firmware",
 		"nmi_panic_self_stop",
 		"panic",
 		"panic_smp_self_stop",
-- 
2.39.2

[PATCH 11/11] x86/hyperv: Mark hv_ghcb_terminate() as noreturn

[Josh Poimboeuf]

From: "Guilherme G. Piccoli" <gpiccoli@igalia.com>

Annotate the function prototype and definition as noreturn to prevent
objtool warnings like:

vmlinux.o: warning: objtool: hyperv_init+0x55c: unreachable instruction

Also, as per Josh's suggestion, add it to the global_noreturns list.
As a comparison, an objdump output without the annotation:

[...]
1b63:  mov    $0x1,%esi
1b68:  xor    %edi,%edi
1b6a:  callq  ffffffff8102f680 <hv_ghcb_terminate>
1b6f:  jmpq   ffffffff82f217ec <hyperv_init+0x9c> # unreachable
1b74:  cmpq   $0xffffffffffffffff,-0x702a24(%rip)
[...]

Now, after adding the __noreturn to the function prototype:

[...]
17df:  callq  ffffffff8102f6d0 <hv_ghcb_negotiate_protocol>
17e4:  test   %al,%al
17e6:  je     ffffffff82f21bb9 <hyperv_init+0x469>
[...]  <many insns>
1bb9:  mov    $0x1,%esi
1bbe:  xor    %edi,%edi
1bc0:  callq  ffffffff8102f680 <hv_ghcb_terminate>
1bc5:  nopw   %cs:0x0(%rax,%rax,1) # end of function

Reported-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/9698eff1-9680-4f0a-94de-590eaa923e94@app.fastmail.com/
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20230317160546.1497477-1-gpiccoli@igalia.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/x86/hyperv/ivm.c           | 2 +-
 arch/x86/include/asm/mshyperv.h | 2 +-
 tools/objtool/check.c           | 1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 1dbcbd9da74d..4f79dc76042d 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -127,7 +127,7 @@ static enum es_result hv_ghcb_hv_call(struct ghcb *ghcb, u64 exit_code,
 		return ES_OK;
 }
 
-void hv_ghcb_terminate(unsigned int set, unsigned int reason)
+void __noreturn hv_ghcb_terminate(unsigned int set, unsigned int reason)
 {
 	u64 val = GHCB_MSR_TERM_REQ;
 
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 4c4c0ec3b62e..09c26e658bcc 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -212,7 +212,7 @@ int hv_set_mem_host_visibility(unsigned long addr, int numpages, bool visible);
 void hv_ghcb_msr_write(u64 msr, u64 value);
 void hv_ghcb_msr_read(u64 msr, u64 *value);
 bool hv_ghcb_negotiate_protocol(void);
-void hv_ghcb_terminate(unsigned int set, unsigned int reason);
+void __noreturn hv_ghcb_terminate(unsigned int set, unsigned int reason);
 #else
 static inline void hv_ghcb_msr_write(u64 msr, u64 value) {}
 static inline void hv_ghcb_msr_read(u64 msr, u64 *value) {}
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8586d4c36600..e23d12041be0 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -213,6 +213,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"ex_handler_msr_mce",
 		"fortify_panic",
 		"hlt_play_dead",
+		"hv_ghcb_terminate",
 		"kthread_complete_and_exit",
 		"kthread_exit",
 		"kunit_try_catch_throw",
-- 
2.39.2