[PATCH v3 17/51] objtool/idle: Validate __cpuidle code as noinstr

Peter Zijlstra
Thu, 12 Jan 2023 19:43:31 -0000

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 at infradead.org>
Acked-by: Geert Uytterhoeven <geert at linux-m68k.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
Acked-by: Frederic Weisbecker <frederic at kernel.org>
Tested-by: Tony Lindgren <tony at atomide.com>
Tested-by: Ulf Hansson <ulf.hansson at linaro.org>
---
 arch/alpha/kernel/vmlinux.lds.S      |    1 -
 arch/arc/kernel/vmlinux.lds.S        |    1 -
 arch/arm/include/asm/vmlinux.lds.h   |    1 -
 arch/arm64/kernel/vmlinux.lds.S      |    1 -
 arch/csky/kernel/vmlinux.lds.S       |    1 -
 arch/hexagon/kernel/vmlinux.lds.S    |    1 -
 arch/ia64/kernel/vmlinux.lds.S       |    1 -
 arch/loongarch/kernel/vmlinux.lds.S  |    1 -
 arch/m68k/kernel/vmlinux-nommu.lds   |    1 -
 arch/m68k/kernel/vmlinux-std.lds     |    1 -
 arch/m68k/kernel/vmlinux-sun3.lds    |    1 -
 arch/microblaze/kernel/vmlinux.lds.S |    1 -
 arch/mips/kernel/vmlinux.lds.S       |    1 -
 arch/nios2/kernel/vmlinux.lds.S      |    1 -
 arch/openrisc/kernel/vmlinux.lds.S   |    1 -
 arch/parisc/kernel/vmlinux.lds.S     |    1 -
 arch/powerpc/kernel/vmlinux.lds.S    |    1 -
 arch/riscv/kernel/vmlinux-xip.lds.S  |    1 -
 arch/riscv/kernel/vmlinux.lds.S      |    1 -
 arch/s390/kernel/vmlinux.lds.S       |    1 -
 arch/sh/kernel/vmlinux.lds.S         |    1 -
 arch/sparc/kernel/vmlinux.lds.S      |    1 -
 arch/um/kernel/dyn.lds.S             |    1 -
 arch/um/kernel/uml.lds.S             |    1 -
 arch/x86/include/asm/irqflags.h      |   11 ++++-------
 arch/x86/include/asm/mwait.h         |    2 +-
 arch/x86/kernel/vmlinux.lds.S        |    1 -
 arch/xtensa/kernel/vmlinux.lds.S     |    1 -
 include/asm-generic/vmlinux.lds.h    |    9 +++------
 include/linux/compiler_types.h       |    8 ++++++--
 include/linux/cpu.h                  |    3 ---
 tools/objtool/check.c                |   13 +++++++++++++
 32 files changed, 27 insertions(+), 45 deletions(-)

--- a/arch/alpha/kernel/vmlinux.lds.S
+++ b/arch/alpha/kernel/vmlinux.lds.S
@@ -27,7 +27,6 @@ SECTIONS
 		HEAD_TEXT
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		*(.fixup)
 		*(.gnu.warning)
--- a/arch/arc/kernel/vmlinux.lds.S
+++ b/arch/arc/kernel/vmlinux.lds.S
@@ -85,7 +85,6 @@ SECTIONS
 		_stext = .;
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
--- a/arch/arm/include/asm/vmlinux.lds.h
+++ b/arch/arm/include/asm/vmlinux.lds.h
@@ -96,7 +96,6 @@
 		SOFTIRQENTRY_TEXT					\
 		TEXT_TEXT						\
 		SCHED_TEXT						\
-		CPUIDLE_TEXT						\
 		LOCK_TEXT						\
 		KPROBES_TEXT						\
 		ARM_STUBS_TEXT						\
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -175,7 +175,6 @@ SECTIONS
 			ENTRY_TEXT
 			TEXT_TEXT
 			SCHED_TEXT
-			CPUIDLE_TEXT
 			LOCK_TEXT
 			KPROBES_TEXT
 			HYPERVISOR_TEXT
--- a/arch/csky/kernel/vmlinux.lds.S
+++ b/arch/csky/kernel/vmlinux.lds.S
@@ -34,7 +34,6 @@ SECTIONS
 		SOFTIRQENTRY_TEXT
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		*(.fixup)
--- a/arch/hexagon/kernel/vmlinux.lds.S
+++ b/arch/hexagon/kernel/vmlinux.lds.S
@@ -41,7 +41,6 @@ SECTIONS
 		IRQENTRY_TEXT
 		SOFTIRQENTRY_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		*(.fixup)
--- a/arch/ia64/kernel/vmlinux.lds.S
+++ b/arch/ia64/kernel/vmlinux.lds.S
@@ -51,7 +51,6 @@ SECTIONS {
 		__end_ivt_text = .;
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
--- a/arch/loongarch/kernel/vmlinux.lds.S
+++ b/arch/loongarch/kernel/vmlinux.lds.S
@@ -42,7 +42,6 @@ SECTIONS
 	.text : {
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
--- a/arch/m68k/kernel/vmlinux-nommu.lds
+++ b/arch/m68k/kernel/vmlinux-nommu.lds
@@ -48,7 +48,6 @@ SECTIONS {
 		IRQENTRY_TEXT
 		SOFTIRQENTRY_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		*(.fixup)
 		. = ALIGN(16);
--- a/arch/m68k/kernel/vmlinux-std.lds
+++ b/arch/m68k/kernel/vmlinux-std.lds
@@ -19,7 +19,6 @@ SECTIONS
 	IRQENTRY_TEXT
 	SOFTIRQENTRY_TEXT
 	SCHED_TEXT
-	CPUIDLE_TEXT
 	LOCK_TEXT
 	*(.fixup)
 	*(.gnu.warning)
--- a/arch/m68k/kernel/vmlinux-sun3.lds
+++ b/arch/m68k/kernel/vmlinux-sun3.lds
@@ -19,7 +19,6 @@ SECTIONS
 	IRQENTRY_TEXT
 	SOFTIRQENTRY_TEXT
 	SCHED_TEXT
-	CPUIDLE_TEXT
 	LOCK_TEXT
 	*(.fixup)
 	*(.gnu.warning)
--- a/arch/microblaze/kernel/vmlinux.lds.S
+++ b/arch/microblaze/kernel/vmlinux.lds.S
@@ -36,7 +36,6 @@ SECTIONS {
 		EXIT_TEXT
 		EXIT_CALL
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -61,7 +61,6 @@ SECTIONS
 	.text : {
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
--- a/arch/nios2/kernel/vmlinux.lds.S
+++ b/arch/nios2/kernel/vmlinux.lds.S
@@ -24,7 +24,6 @@ SECTIONS
 	.text : {
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		IRQENTRY_TEXT
 		SOFTIRQENTRY_TEXT
--- a/arch/openrisc/kernel/vmlinux.lds.S
+++ b/arch/openrisc/kernel/vmlinux.lds.S
@@ -52,7 +52,6 @@ SECTIONS
           _stext = .;
 	  TEXT_TEXT
 	  SCHED_TEXT
-	  CPUIDLE_TEXT
 	  LOCK_TEXT
 	  KPROBES_TEXT
 	  IRQENTRY_TEXT
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -86,7 +86,6 @@ SECTIONS
 		TEXT_TEXT
 		LOCK_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
 		SOFTIRQENTRY_TEXT
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -111,7 +111,6 @@ SECTIONS
 #endif
 		NOINSTR_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
--- a/arch/riscv/kernel/vmlinux-xip.lds.S
+++ b/arch/riscv/kernel/vmlinux-xip.lds.S
@@ -39,7 +39,6 @@ SECTIONS
 		_stext = .;
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		ENTRY_TEXT
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -42,7 +42,6 @@ SECTIONS
 		_stext = .;
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		ENTRY_TEXT
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -42,7 +42,6 @@ SECTIONS
 		HEAD_TEXT
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
--- a/arch/sh/kernel/vmlinux.lds.S
+++ b/arch/sh/kernel/vmlinux.lds.S
@@ -29,7 +29,6 @@ SECTIONS
 		HEAD_TEXT
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
--- a/arch/sparc/kernel/vmlinux.lds.S
+++ b/arch/sparc/kernel/vmlinux.lds.S
@@ -50,7 +50,6 @@ SECTIONS
 		HEAD_TEXT
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		IRQENTRY_TEXT
--- a/arch/um/kernel/dyn.lds.S
+++ b/arch/um/kernel/dyn.lds.S
@@ -74,7 +74,6 @@ SECTIONS
     _stext = .;
     TEXT_TEXT
     SCHED_TEXT
-    CPUIDLE_TEXT
     LOCK_TEXT
     IRQENTRY_TEXT
     SOFTIRQENTRY_TEXT
--- a/arch/um/kernel/uml.lds.S
+++ b/arch/um/kernel/uml.lds.S
@@ -35,7 +35,6 @@ SECTIONS
     _stext = .;
     TEXT_TEXT
     SCHED_TEXT
-    CPUIDLE_TEXT
     LOCK_TEXT
     IRQENTRY_TEXT
     SOFTIRQENTRY_TEXT
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -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:
  */
@@ -45,13 +42,13 @@ static __always_inline void native_irq_e
 	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");
@@ -84,7 +81,7 @@ static __always_inline void arch_local_i
  * 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();
 }
@@ -93,7 +90,7 @@ static inline __cpuidle void arch_safe_h
  * 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();
 }
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -105,7 +105,7 @@ static inline void __sti_mwait(unsigned
  * 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)) {
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -129,7 +129,6 @@ SECTIONS
 		HEAD_TEXT
 		TEXT_TEXT
 		SCHED_TEXT
-		CPUIDLE_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
 		SOFTIRQENTRY_TEXT
--- a/arch/xtensa/kernel/vmlinux.lds.S
+++ b/arch/xtensa/kernel/vmlinux.lds.S
@@ -125,7 +125,6 @@ SECTIONS
     ENTRY_TEXT
     TEXT_TEXT
     SCHED_TEXT
-    CPUIDLE_TEXT
     LOCK_TEXT
     *(.fixup)
   }
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -580,6 +580,9 @@
 		ALIGN_FUNCTION();					\
 		__noinstr_text_start = .;				\
 		*(.noinstr.text)					\
+		__cpuidle_text_start = .;				\
+		*(.cpuidle.text)					\
+		__cpuidle_text_end = .;					\
 		__noinstr_text_end = .;

 /*
@@ -620,12 +623,6 @@
 		*(.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 = .;				\
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -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__ */
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -176,9 +176,6 @@ void __noreturn cpu_startup_entry(enum c

 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);
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -376,6 +376,7 @@ static int decode_instructions(struct ob

 		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;

@@ -3361,6 +3362,12 @@ static inline bool noinstr_call_dest(str
 		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,
 	 * let them proceed to get the message out.
@@ -4155,6 +4162,12 @@ static int validate_noinstr_sections(str
 	if (sec) {
 		warnings += validate_section(file, sec);
 		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;