path: root/arch/x86/include
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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-28 09:42:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-28 09:42:47 -0700
commita358505d8af3ab43763e1b49549619528783d2bf (patch)
tree9486032ab6cfad055f0cffabbf0edc48fce77c52 /arch/x86/include
parent719fdd32921fb7e3208db8832d32ae1c2d68900f (diff)
parent2c92d787cc9fad57d05c96bd117782183768258a (diff)
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
Diffstat (limited to 'arch/x86/include')
4 files changed, 26 insertions, 6 deletions
diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
index 35460fef39b8..0367efdc5b7a 100644
--- a/arch/x86/include/asm/bitops.h
+++ b/arch/x86/include/asm/bitops.h
@@ -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;
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index fb34ff641e0a..028189575560 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -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(); \
diff --git a/arch/x86/include/asm/cpumask.h b/arch/x86/include/asm/cpumask.h
index 6722ffcef2e6..3afa990d756b 100644
--- a/arch/x86/include/asm/cpumask.h
+++ b/arch/x86/include/asm/cpumask.h
@@ -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));
+static __always_inline bool arch_cpu_online(int cpu)
+ return cpu == 0;
+#define arch_cpu_is_offline(cpu) unlikely(!arch_cpu_online(cpu))
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_CPUMASK_H */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 42cd333616c4..03b7c4ca425a 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -370,7 +370,7 @@ struct x86_hw_tss {
struct entry_stack {
- unsigned long words[64];
+ char stack[PAGE_SIZE];
struct entry_stack_page {