arch/x86/include/asm/smp.h | 4 ++-- arch/x86/kernel/acpi/cstate.c | 2 +- include/acpi/processor.h | 6 +++--- tools/objtool/noreturns.h | 2 ++ 4 files changed, 8 insertions(+), 6 deletions(-)
Fix some related issues (done in a single patch to avoid introducing
intermediate bisect warnings):
1) The SMP version of mwait_play_dead() doesn't return, but its
!SMP counterpart does. Make its calling behavior consistent by
resolving the !SMP version to a BUG(). It should never be called
anyway, this just enforces that at runtime and enables its callers
to be marked as __noreturn.
2) While the SMP definition of mwait_play_dead() is annotated as
__noreturn, the declaration isn't. Nor is it listed in
tools/objtool/noreturns.h. Fix that.
3) Similar to #1, the SMP version of acpi_processor_ffh_play_dead()
doesn't return but its !SMP counterpart does. Make the !SMP
version a BUG(). It should never be called.
4) acpi_processor_ffh_play_dead() doesn't return, but is lacking any
__noreturn annotations. Fix that.
This fixes the following warnings:
vmlinux.o: warning: objtool: acpi_processor_ffh_play_dead+0x67: mwait_play_dead() is missing a __noreturn annotation
vmlinux.o: warning: objtool: acpi_idle_play_dead+0x3c: acpi_processor_ffh_play_dead() is missing a __noreturn annotation
Fixes: a7dd183f0b38 ("x86/smp: Allow calling mwait_play_dead with an arbitrary hint")
Fixes: 541ddf31e300 ("ACPI/processor_idle: Add FFH state handling")
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/include/asm/smp.h | 4 ++--
arch/x86/kernel/acpi/cstate.c | 2 +-
include/acpi/processor.h | 6 +++---
tools/objtool/noreturns.h | 2 ++
4 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 80f8bfd83fc7..1d3b11eba084 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -114,7 +114,7 @@ void wbinvd_on_cpu(int cpu);
int wbinvd_on_all_cpus(void);
void smp_kick_mwait_play_dead(void);
-void mwait_play_dead(unsigned int eax_hint);
+void __noreturn mwait_play_dead(unsigned int eax_hint);
void native_smp_send_reschedule(int cpu);
void native_send_call_func_ipi(const struct cpumask *mask);
@@ -166,7 +166,7 @@ static inline struct cpumask *cpu_llc_shared_mask(int cpu)
return (struct cpumask *)cpumask_of(0);
}
-static inline void mwait_play_dead(unsigned int eax_hint) { }
+static inline void __noreturn mwait_play_dead(unsigned int eax_hint) { BUG(); }
#endif /* CONFIG_SMP */
#ifdef CONFIG_DEBUG_NMI_SELFTEST
diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index 86c87c01d23d..d25584255ab8 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -206,7 +206,7 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
}
EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
-void acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
+void __noreturn acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
{
unsigned int cpu = smp_processor_id();
struct cstate_entry *percpu_entry;
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 63a37e72b721..d0eccbd920e5 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -280,7 +280,7 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
struct acpi_processor_cx *cx,
struct acpi_power_register *reg);
void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cstate);
-void acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx);
+void __noreturn acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx);
#else
static inline void acpi_processor_power_init_bm_check(struct
acpi_processor_flags
@@ -301,9 +301,9 @@ static inline void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx
{
return;
}
-static inline void acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
+static inline void __noreturn acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
{
- return;
+ BUG();
}
#endif
diff --git a/tools/objtool/noreturns.h b/tools/objtool/noreturns.h
index b2174894f9f7..5a4aec4c4639 100644
--- a/tools/objtool/noreturns.h
+++ b/tools/objtool/noreturns.h
@@ -16,6 +16,7 @@ NORETURN(__tdx_hypercall_failed)
NORETURN(__ubsan_handle_builtin_unreachable)
NORETURN(__x64_sys_exit)
NORETURN(__x64_sys_exit_group)
+NORETURN(acpi_processor_ffh_play_dead)
NORETURN(arch_cpu_idle_dead)
NORETURN(bch2_trans_in_restart_error)
NORETURN(bch2_trans_restart_error)
@@ -34,6 +35,7 @@ NORETURN(kunit_try_catch_throw)
NORETURN(machine_real_restart)
NORETURN(make_task_dead)
NORETURN(mpt_halt_firmware)
+NORETURN(mwait_play_dead)
NORETURN(nmi_panic_self_stop)
NORETURN(panic)
NORETURN(panic_smp_self_stop)
--
2.48.1On 3/3/2025 1:48 AM, Josh Poimboeuf wrote:
> Fix some related issues (done in a single patch to avoid introducing
> intermediate bisect warnings):
>
> 1) The SMP version of mwait_play_dead() doesn't return, but its
> !SMP counterpart does. Make its calling behavior consistent by
> resolving the !SMP version to a BUG(). It should never be called
> anyway, this just enforces that at runtime and enables its callers
> to be marked as __noreturn.
>
> 2) While the SMP definition of mwait_play_dead() is annotated as
> __noreturn, the declaration isn't. Nor is it listed in
> tools/objtool/noreturns.h. Fix that.
>
> 3) Similar to #1, the SMP version of acpi_processor_ffh_play_dead()
> doesn't return but its !SMP counterpart does. Make the !SMP
> version a BUG(). It should never be called.
>
> 4) acpi_processor_ffh_play_dead() doesn't return, but is lacking any
> __noreturn annotations. Fix that.
>
> This fixes the following warnings:
>
> vmlinux.o: warning: objtool: acpi_processor_ffh_play_dead+0x67: mwait_play_dead() is missing a __noreturn annotation
> vmlinux.o: warning: objtool: acpi_idle_play_dead+0x3c: acpi_processor_ffh_play_dead() is missing a __noreturn annotation
>
> Fixes: a7dd183f0b38 ("x86/smp: Allow calling mwait_play_dead with an arbitrary hint")
> Fixes: 541ddf31e300 ("ACPI/processor_idle: Add FFH state handling")
> Reported-by: Paul E. McKenney <paulmck@kernel.org>
> Tested-by: Paul E. McKenney <paulmck@kernel.org>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> arch/x86/include/asm/smp.h | 4 ++--
> arch/x86/kernel/acpi/cstate.c | 2 +-
> include/acpi/processor.h | 6 +++---
> tools/objtool/noreturns.h | 2 ++
> 4 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
> index 80f8bfd83fc7..1d3b11eba084 100644
> --- a/arch/x86/include/asm/smp.h
> +++ b/arch/x86/include/asm/smp.h
> @@ -114,7 +114,7 @@ void wbinvd_on_cpu(int cpu);
> int wbinvd_on_all_cpus(void);
>
> void smp_kick_mwait_play_dead(void);
> -void mwait_play_dead(unsigned int eax_hint);
> +void __noreturn mwait_play_dead(unsigned int eax_hint);
>
> void native_smp_send_reschedule(int cpu);
> void native_send_call_func_ipi(const struct cpumask *mask);
> @@ -166,7 +166,7 @@ static inline struct cpumask *cpu_llc_shared_mask(int cpu)
> return (struct cpumask *)cpumask_of(0);
> }
>
> -static inline void mwait_play_dead(unsigned int eax_hint) { }
> +static inline void __noreturn mwait_play_dead(unsigned int eax_hint) { BUG(); }
> #endif /* CONFIG_SMP */
>
> #ifdef CONFIG_DEBUG_NMI_SELFTEST
> diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
> index 86c87c01d23d..d25584255ab8 100644
> --- a/arch/x86/kernel/acpi/cstate.c
> +++ b/arch/x86/kernel/acpi/cstate.c
> @@ -206,7 +206,7 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
> }
> EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
>
> -void acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
> +void __noreturn acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
> {
> unsigned int cpu = smp_processor_id();
> struct cstate_entry *percpu_entry;
> diff --git a/include/acpi/processor.h b/include/acpi/processor.h
> index 63a37e72b721..d0eccbd920e5 100644
> --- a/include/acpi/processor.h
> +++ b/include/acpi/processor.h
> @@ -280,7 +280,7 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
> struct acpi_processor_cx *cx,
> struct acpi_power_register *reg);
> void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cstate);
> -void acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx);
> +void __noreturn acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx);
> #else
> static inline void acpi_processor_power_init_bm_check(struct
> acpi_processor_flags
> @@ -301,9 +301,9 @@ static inline void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx
> {
> return;
> }
> -static inline void acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
> +static inline void __noreturn acpi_processor_ffh_play_dead(struct acpi_processor_cx *cx)
> {
> - return;
> + BUG();
> }
> #endif
>
> diff --git a/tools/objtool/noreturns.h b/tools/objtool/noreturns.h
> index b2174894f9f7..5a4aec4c4639 100644
> --- a/tools/objtool/noreturns.h
> +++ b/tools/objtool/noreturns.h
> @@ -16,6 +16,7 @@ NORETURN(__tdx_hypercall_failed)
> NORETURN(__ubsan_handle_builtin_unreachable)
> NORETURN(__x64_sys_exit)
> NORETURN(__x64_sys_exit_group)
> +NORETURN(acpi_processor_ffh_play_dead)
> NORETURN(arch_cpu_idle_dead)
> NORETURN(bch2_trans_in_restart_error)
> NORETURN(bch2_trans_restart_error)
> @@ -34,6 +35,7 @@ NORETURN(kunit_try_catch_throw)
> NORETURN(machine_real_restart)
> NORETURN(make_task_dead)
> NORETURN(mpt_halt_firmware)
> +NORETURN(mwait_play_dead)
> NORETURN(nmi_panic_self_stop)
> NORETURN(panic)
> NORETURN(panic_smp_self_stop)
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