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

Peter Zijlstra
2023-01-12T20:05:03Z

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>
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>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@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;