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objtool/idle: Validate __cpuidle code as noinstr
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Idle code is very like entry code in that RCU isn't available. As
such, add a little validation.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195540.373461409@infradead.org
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Peter Zijlstra authored and Ingo Molnar committed Jan 13, 2023
1 parent 00717eb commit 2b5a0e4
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Showing 32 changed files with 27 additions and 45 deletions.
1 change: 0 additions & 1 deletion arch/alpha/kernel/vmlinux.lds.S
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Expand Up @@ -27,7 +27,6 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
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1 change: 0 additions & 1 deletion arch/arc/kernel/vmlinux.lds.S
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Expand Up @@ -85,7 +85,6 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/arm/include/asm/vmlinux.lds.h
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Expand Up @@ -96,7 +96,6 @@
SOFTIRQENTRY_TEXT \
TEXT_TEXT \
SCHED_TEXT \
CPUIDLE_TEXT \
LOCK_TEXT \
KPROBES_TEXT \
ARM_STUBS_TEXT \
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1 change: 0 additions & 1 deletion arch/arm64/kernel/vmlinux.lds.S
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Expand Up @@ -175,7 +175,6 @@ SECTIONS
ENTRY_TEXT
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
HYPERVISOR_TEXT
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1 change: 0 additions & 1 deletion arch/csky/kernel/vmlinux.lds.S
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Expand Up @@ -34,7 +34,6 @@ SECTIONS
SOFTIRQENTRY_TEXT
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.fixup)
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1 change: 0 additions & 1 deletion arch/hexagon/kernel/vmlinux.lds.S
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Expand Up @@ -41,7 +41,6 @@ SECTIONS
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.fixup)
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1 change: 0 additions & 1 deletion arch/ia64/kernel/vmlinux.lds.S
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Expand Up @@ -51,7 +51,6 @@ SECTIONS {
__end_ivt_text = .;
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/loongarch/kernel/vmlinux.lds.S
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Expand Up @@ -43,7 +43,6 @@ SECTIONS
.text : {
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/m68k/kernel/vmlinux-nommu.lds
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Expand Up @@ -48,7 +48,6 @@ SECTIONS {
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
. = ALIGN(16);
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1 change: 0 additions & 1 deletion arch/m68k/kernel/vmlinux-std.lds
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Expand Up @@ -19,7 +19,6 @@ SECTIONS
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
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1 change: 0 additions & 1 deletion arch/m68k/kernel/vmlinux-sun3.lds
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Expand Up @@ -19,7 +19,6 @@ SECTIONS
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
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1 change: 0 additions & 1 deletion arch/microblaze/kernel/vmlinux.lds.S
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Expand Up @@ -36,7 +36,6 @@ SECTIONS {
EXIT_TEXT
EXIT_CALL
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/mips/kernel/vmlinux.lds.S
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Expand Up @@ -61,7 +61,6 @@ SECTIONS
.text : {
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/nios2/kernel/vmlinux.lds.S
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Expand Up @@ -24,7 +24,6 @@ SECTIONS
.text : {
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/openrisc/kernel/vmlinux.lds.S
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Expand Up @@ -52,7 +52,6 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/parisc/kernel/vmlinux.lds.S
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Expand Up @@ -86,7 +86,6 @@ SECTIONS
TEXT_TEXT
LOCK_TEXT
SCHED_TEXT
CPUIDLE_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/powerpc/kernel/vmlinux.lds.S
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Expand Up @@ -111,7 +111,6 @@ SECTIONS
#endif
NOINSTR_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/riscv/kernel/vmlinux-xip.lds.S
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Expand Up @@ -39,7 +39,6 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
ENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/riscv/kernel/vmlinux.lds.S
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Expand Up @@ -42,7 +42,6 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
ENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/s390/kernel/vmlinux.lds.S
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Expand Up @@ -42,7 +42,6 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/sh/kernel/vmlinux.lds.S
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Expand Up @@ -29,7 +29,6 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/sparc/kernel/vmlinux.lds.S
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Expand Up @@ -50,7 +50,6 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/um/kernel/dyn.lds.S
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Expand Up @@ -74,7 +74,6 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/um/kernel/uml.lds.S
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Expand Up @@ -35,7 +35,6 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
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11 changes: 4 additions & 7 deletions arch/x86/include/asm/irqflags.h
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Expand Up @@ -8,9 +8,6 @@

#include <asm/nospec-branch.h>

/* Provide __cpuidle; we can't safely include <linux/cpu.h> */
#define __cpuidle __section(".cpuidle.text")

/*
* Interrupt control:
*/
Expand Down Expand Up @@ -45,13 +42,13 @@ static __always_inline void native_irq_enable(void)
asm volatile("sti": : :"memory");
}

static inline __cpuidle void native_safe_halt(void)
static __always_inline void native_safe_halt(void)
{
mds_idle_clear_cpu_buffers();
asm volatile("sti; hlt": : :"memory");
}

static inline __cpuidle void native_halt(void)
static __always_inline void native_halt(void)
{
mds_idle_clear_cpu_buffers();
asm volatile("hlt": : :"memory");
Expand Down Expand Up @@ -84,7 +81,7 @@ static __always_inline void arch_local_irq_enable(void)
* Used in the idle loop; sti takes one instruction cycle
* to complete:
*/
static inline __cpuidle void arch_safe_halt(void)
static __always_inline void arch_safe_halt(void)
{
native_safe_halt();
}
Expand All @@ -93,7 +90,7 @@ static inline __cpuidle void arch_safe_halt(void)
* Used when interrupts are already enabled or to
* shutdown the processor:
*/
static inline __cpuidle void halt(void)
static __always_inline void halt(void)
{
native_halt();
}
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2 changes: 1 addition & 1 deletion arch/x86/include/asm/mwait.h
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Expand Up @@ -105,7 +105,7 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
* New with Core Duo processors, MWAIT can take some hints based on CPU
* capability.
*/
static inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
static __always_inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
{
if (static_cpu_has_bug(X86_BUG_MONITOR) || !current_set_polling_and_test()) {
if (static_cpu_has_bug(X86_BUG_CLFLUSH_MONITOR)) {
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1 change: 0 additions & 1 deletion arch/x86/kernel/vmlinux.lds.S
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Expand Up @@ -129,7 +129,6 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
SOFTIRQENTRY_TEXT
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1 change: 0 additions & 1 deletion arch/xtensa/kernel/vmlinux.lds.S
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Expand Up @@ -125,7 +125,6 @@ SECTIONS
ENTRY_TEXT
TEXT_TEXT
SCHED_TEXT
CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
}
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9 changes: 3 additions & 6 deletions include/asm-generic/vmlinux.lds.h
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Expand Up @@ -558,6 +558,9 @@
ALIGN_FUNCTION(); \
__noinstr_text_start = .; \
*(.noinstr.text) \
__cpuidle_text_start = .; \
*(.cpuidle.text) \
__cpuidle_text_end = .; \
__noinstr_text_end = .;

/*
Expand Down Expand Up @@ -598,12 +601,6 @@
*(.spinlock.text) \
__lock_text_end = .;

#define CPUIDLE_TEXT \
ALIGN_FUNCTION(); \
__cpuidle_text_start = .; \
*(.cpuidle.text) \
__cpuidle_text_end = .;

#define KPROBES_TEXT \
ALIGN_FUNCTION(); \
__kprobes_text_start = .; \
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8 changes: 6 additions & 2 deletions include/linux/compiler_types.h
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Expand Up @@ -232,11 +232,15 @@ struct ftrace_likely_data {
#endif

/* Section for code which can't be instrumented at all */
#define noinstr \
noinline notrace __attribute((__section__(".noinstr.text"))) \
#define __noinstr_section(section) \
noinline notrace __attribute((__section__(section))) \
__no_kcsan __no_sanitize_address __no_profile __no_sanitize_coverage \
__no_sanitize_memory

#define noinstr __noinstr_section(".noinstr.text")

#define __cpuidle __noinstr_section(".cpuidle.text")

#endif /* __KERNEL__ */

#endif /* __ASSEMBLY__ */
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3 changes: 0 additions & 3 deletions include/linux/cpu.h
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Expand Up @@ -176,9 +176,6 @@ void __noreturn cpu_startup_entry(enum cpuhp_state state);

void cpu_idle_poll_ctrl(bool enable);

/* Attach to any functions which should be considered cpuidle. */
#define __cpuidle __section(".cpuidle.text")

bool cpu_in_idle(unsigned long pc);

void arch_cpu_idle(void);
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13 changes: 13 additions & 0 deletions tools/objtool/check.c
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Expand Up @@ -376,6 +376,7 @@ static int decode_instructions(struct objtool_file *file)

if (!strcmp(sec->name, ".noinstr.text") ||
!strcmp(sec->name, ".entry.text") ||
!strcmp(sec->name, ".cpuidle.text") ||
!strncmp(sec->name, ".text.__x86.", 12))
sec->noinstr = true;

Expand Down Expand Up @@ -3365,6 +3366,12 @@ static inline bool noinstr_call_dest(struct objtool_file *file,
if (func->sec->noinstr)
return true;

/*
* If the symbol is a static_call trampoline, we can't tell.
*/
if (func->static_call_tramp)
return true;

/*
* The __ubsan_handle_*() calls are like WARN(), they only happen when
* something 'BAD' happened. At the risk of taking the machine down,
Expand Down Expand Up @@ -4162,6 +4169,12 @@ static int validate_noinstr_sections(struct objtool_file *file)
warnings += validate_unwind_hints(file, sec);
}

sec = find_section_by_name(file->elf, ".cpuidle.text");
if (sec) {
warnings += validate_section(file, sec);
warnings += validate_unwind_hints(file, sec);
}

return warnings;
}

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