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A set of objtool fixes:

Browse Source 
- Handle __ubsan_handle_builtin_unreachable() correctly and treat it as
     noreturn.
 
   - Allow architectures to select uaccess validation
 
   - Use the non-instrumented bit test for test_cpu_has() to prevent escape
     from non-instrumentable regions.
 
   - Use arch_ prefixed atomics for JUMP_LABEL=n builds to prevent escape
     from non-instrumentable regions.
 
   - Mark a few tiny inline as __always_inline to prevent GCC from bringing
     them out of line and instrumenting them.
 
   - Mark the empty stub context_tracking_enabled() as always inline as GCC
     brings them out of line and instruments the empty shell.
 
   - Annotate ex_handler_msr_mce() as dead end
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Merge tag 'objtool-urgent-2022-06-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fixes from Thomas Gleixner:

 - Handle __ubsan_handle_builtin_unreachable() correctly and treat it as
   noreturn

 - Allow architectures to select uaccess validation

 - Use the non-instrumented bit test for test_cpu_has() to prevent
   escape from non-instrumentable regions

 - Use arch_ prefixed atomics for JUMP_LABEL=n builds to prevent escape
   from non-instrumentable regions

 - Mark a few tiny inline as __always_inline to prevent GCC from
   bringing them out of line and instrumenting them

 - Mark the empty stub context_tracking_enabled() as always inline as
   GCC brings them out of line and instruments the empty shell

 - Annotate ex_handler_msr_mce() as dead end

* tag 'objtool-urgent-2022-06-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/extable: Annotate ex_handler_msr_mce() as a dead end
  context_tracking: Always inline empty stubs
  x86: Always inline on_thread_stack() and current_top_of_stack()
  jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds
  x86/cpu: Elide KCSAN for cpu_has() and friends
  objtool: Mark __ubsan_handle_builtin_unreachable() as noreturn
  objtool: Add CONFIG_HAVE_UACCESS_VALIDATION
This commit is contained in:
Linus Torvalds 2022-06-05 09:45:27 -07:00
commit 44688ffd11
9 changed files with 24 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/Kconfig
View File

@ -1048,6 +1048,10 @@ config HAVE_NOINSTR_HACK
config HAVE_NOINSTR_VALIDATION
bool
config HAVE_UACCESS_VALIDATION
bool
select OBJTOOL
config HAVE_STACK_VALIDATION
bool
help

1
arch/x86/Kconfig
View File

@ -258,6 +258,7 @@ config X86
select HAVE_PREEMPT_DYNAMIC_CALL
select HAVE_RSEQ
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
select HAVE_UNSTABLE_SCHED_CLOCK
select HAVE_USER_RETURN_NOTIFIER
select HAVE_GENERIC_VDSO

2
arch/x86/include/asm/cpufeature.h
View File

@ -54,7 +54,7 @@ extern const char * const x86_power_flags[32];
extern const char * const x86_bug_flags[NBUGINTS*32];
#define test_cpu_cap(c, bit) \
test_bit(bit, (unsigned long *)((c)->x86_capability))
arch_test_bit(bit, (unsigned long *)((c)->x86_capability))
/*
* There are 32 bits/features in each mask word. The high bits

8
arch/x86/include/asm/extable.h
View File

@ -42,9 +42,13 @@ extern int ex_get_fixup_type(unsigned long ip);
extern void early_fixup_exception(struct pt_regs *regs, int trapnr);
#ifdef CONFIG_X86_MCE
extern void ex_handler_msr_mce(struct pt_regs *regs, bool wrmsr);
extern void __noreturn ex_handler_msr_mce(struct pt_regs *regs, bool wrmsr);
#else
static inline void ex_handler_msr_mce(struct pt_regs *regs, bool wrmsr) { }
static inline void __noreturn ex_handler_msr_mce(struct pt_regs *regs, bool wrmsr)
{
for (;;)
cpu_relax();
}
#endif
#if defined(CONFIG_BPF_JIT) && defined(CONFIG_X86_64)

4
arch/x86/include/asm/processor.h
View File

@ -559,7 +559,7 @@ static __always_inline void native_swapgs(void)
#endif
}
static inline unsigned long current_top_of_stack(void)
static __always_inline unsigned long current_top_of_stack(void)
{
/*
* We can't read directly from tss.sp0: sp0 on x86_32 is special in
@ -569,7 +569,7 @@ static inline unsigned long current_top_of_stack(void)
return this_cpu_read_stable(cpu_current_top_of_stack);
}
static inline bool on_thread_stack(void)
static __always_inline bool on_thread_stack(void)
{
return (unsigned long)(current_top_of_stack() -
current_stack_pointer) < THREAD_SIZE;

8
include/linux/context_tracking_state.h
View File

@ -46,10 +46,10 @@ static __always_inline bool context_tracking_in_user(void)
return __this_cpu_read(context_tracking.state) == CONTEXT_USER;
}
#else
static inline bool context_tracking_in_user(void) { return false; }
static inline bool context_tracking_enabled(void) { return false; }
static inline bool context_tracking_enabled_cpu(int cpu) { return false; }
static inline bool context_tracking_enabled_this_cpu(void) { return false; }
static __always_inline bool context_tracking_in_user(void) { return false; }
static __always_inline bool context_tracking_enabled(void) { return false; }
static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; }
static __always_inline bool context_tracking_enabled_this_cpu(void) { return false; }
#endif /* CONFIG_CONTEXT_TRACKING */
#endif

4
include/linux/jump_label.h
View File

@ -256,9 +256,9 @@ extern void static_key_disable_cpuslocked(struct static_key *key);
#include <linux/atomic.h>
#include <linux/bug.h>
static inline int static_key_count(struct static_key *key)
static __always_inline int static_key_count(struct static_key *key)
{
return atomic_read(&key->enabled);
return arch_atomic_read(&key->enabled);
}
static __always_inline void jump_label_init(void)

2
scripts/Makefile.lib
View File

@ -239,7 +239,7 @@ objtool_args = \
$(if $(CONFIG_SLS), --sls) \
$(if $(CONFIG_STACK_VALIDATION), --stackval) \
$(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call) \
--uaccess \
$(if $(CONFIG_HAVE_UACCESS_VALIDATION), --uaccess) \
$(if $(delay-objtool), --link) \
$(if $(part-of-module), --module) \
$(if $(CONFIG_GCOV_KERNEL), --no-unreachable)

4
tools/objtool/check.c
View File

@ -185,7 +185,9 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
"do_group_exit",
"stop_this_cpu",
"__invalid_creds",
"cpu_startup_entry",
"cpu_startup_entry",
"__ubsan_handle_builtin_unreachable",
"ex_handler_msr_mce",
};
if (!func)