[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20220519213422.059293174@infradead.org>
Date: Thu, 19 May 2022 23:27:58 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: frederic@...nel.org, paulmck@...nel.org, rjw@...ysocki.net,
x86@...nel.org
Cc: linux-kernel@...r.kernel.org, peterz@...radead.org,
jpoimboe@...nel.org
Subject: [RFC][PATCH 8/9] objtool/idle: Validate __cpuidle code as noinstr
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@...radead.org>
---
arch/x86/include/asm/irqflags.h | 11 ++++-------
arch/x86/include/asm/mwait.h | 2 +-
include/linux/compiler_types.h | 8 ++++++--
include/linux/cpu.h | 3 ---
tools/objtool/check.c | 15 ++++++++++++++-
5 files changed, 25 insertions(+), 14 deletions(-)
--- 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
@@ -104,7 +104,7 @@ 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/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -225,10 +225,14 @@ 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
+#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
@@ -171,9 +171,6 @@ 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
@@ -373,7 +373,8 @@ static int decode_instructions(struct ob
sec->text = true;
if (!strcmp(sec->name, ".noinstr.text") ||
- !strcmp(sec->name, ".entry.text"))
+ !strcmp(sec->name, ".entry.text") ||
+ !strcmp(sec->name, ".cpuidle.text"))
sec->noinstr = true;
for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
@@ -3077,6 +3078,12 @@ 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.
@@ -3645,6 +3652,12 @@ 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;
Powered by blists - more mailing lists