Commit a358505d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_entry_for_5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 entry fixes from Borislav Petkov:
 "This is the x86/entry urgent pile which has accumulated since the
  merge window.

  It is not the smallest but considering the almost complete entry core
  rewrite, the amount of fixes to follow is somewhat higher than usual,
  which is to be expected.

  Peter Zijlstra says:
   'These patches address a number of instrumentation issues that were
    found after the x86/entry overhaul. When combined with rcu/urgent
    and objtool/urgent, these patches make UBSAN/KASAN/KCSAN happy
    again.

    Part of making this all work is bumping the minimum GCC version for
    KASAN builds to gcc-8.3, the reason for this is that the
    __no_sanitize_address function attribute is broken in GCC releases
    before that.

    No known GCC version has a working __no_sanitize_undefined, however
    because the only noinstr violation that results from this happens
    when an UB is found, we treat it like WARN. That is, we allow it to
    violate the noinstr rules in order to get the warning out'"

* tag 'x86_entry_for_5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/entry: Fix #UD vs WARN more
  x86/entry: Increase entry_stack size to a full page
  x86/entry: Fixup bad_iret vs noinstr
  objtool: Don't consider vmlinux a C-file
  kasan: Fix required compiler version
  compiler_attributes.h: Support no_sanitize_undefined check with GCC 4
  x86/entry, bug: Comment the instrumentation_begin() usage for WARN()
  x86/entry, ubsan, objtool: Whitelist __ubsan_handle_*()
  x86/entry, cpumask: Provide non-instrumented variant of cpu_is_offline()
  compiler_types.h: Add __no_sanitize_{address,undefined} to noinstr
  kasan: Bump required compiler version
  x86, kcsan: Add __no_kcsan to noinstr
  kcsan: Remove __no_kcsan_or_inline
  x86, kcsan: Remove __no_kcsan_or_inline usage
parents 719fdd32 2c92d787

Documentation/dev-tools/kcsan.rst

+0 −6
Original line number Diff line number Diff line
@@ -114,12 +114,6 @@ the below options are available: 
  To dynamically limit for which functions to generate reports, see the

  `DebugFS interface`_ blacklist/whitelist feature.



  For ``__always_inline`` functions, replace ``__always_inline`` with

  ``__no_kcsan_or_inline`` (which implies ``__always_inline``)::



    static __no_kcsan_or_inline void foo(void) {

        ...



* To disable data race detection for a particular compilation unit, add to the

  ``Makefile``::

arch/x86/include/asm/bitops.h

+1 −5
Original line number Diff line number Diff line
@@ -201,12 +201,8 @@ arch_test_and_change_bit(long nr, volatile unsigned long *addr) 
	return GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(btc), *addr, c, "Ir", nr);

}



static __no_kcsan_or_inline bool constant_test_bit(long nr, const volatile unsigned long *addr)

static __always_inline bool constant_test_bit(long nr, const volatile unsigned long *addr)

{

	/*

	 * Because this is a plain access, we need to disable KCSAN here to

	 * avoid double instrumentation via instrumented bitops.

	 */

	return ((1UL << (nr & (BITS_PER_LONG-1))) &

		(addr[nr >> _BITOPS_LONG_SHIFT])) != 0;

}

arch/x86/include/asm/bug.h

+6 −0
Original line number Diff line number Diff line
@@ -75,6 +75,12 @@ do { \ 
	unreachable();						\

} while (0)



/*

 * This instrumentation_begin() is strictly speaking incorrect; but it

 * suppresses the complaints from WARN()s in noinstr code. If such a WARN()

 * were to trigger, we'd rather wreck the machine in an attempt to get the

 * message out than not know about it.

 */

#define __WARN_FLAGS(flags)					\

do {								\

	instrumentation_begin();				\

arch/x86/include/asm/cpumask.h

+18 −0
Original line number Diff line number Diff line
@@ -11,5 +11,23 @@ extern cpumask_var_t cpu_sibling_setup_mask; 


extern void setup_cpu_local_masks(void);



/*

 * NMI and MCE exceptions need cpu_is_offline() _really_ early,

 * provide an arch_ special for them to avoid instrumentation.

 */

#if NR_CPUS > 1

static __always_inline bool arch_cpu_online(int cpu)

{

	return arch_test_bit(cpu, cpumask_bits(cpu_online_mask));

}

#else

static __always_inline bool arch_cpu_online(int cpu)

{

	return cpu == 0;

}

#endif



#define arch_cpu_is_offline(cpu)	unlikely(!arch_cpu_online(cpu))



#endif /* __ASSEMBLY__ */

#endif /* _ASM_X86_CPUMASK_H */

arch/x86/include/asm/processor.h

+1 −1
Original line number Diff line number Diff line
@@ -370,7 +370,7 @@ struct x86_hw_tss { 
#define IO_BITMAP_OFFSET_INVALID	(__KERNEL_TSS_LIMIT + 1)



struct entry_stack {

	unsigned long		words[64];

	char	stack[PAGE_SIZE];

};



struct entry_stack_page {

CRA Git | Maintained and supported by SUSTech CRA and CCSE