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-rw-r--r--include/linux/kernel.h64
1 files changed, 46 insertions, 18 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 350dfb08aee3..f31638c6e873 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -202,26 +202,26 @@ extern int _cond_resched(void);
/**
* abs - return absolute value of an argument
- * @x: the value. If it is unsigned type, it is converted to signed type first
- * (s64, long or int depending on its size).
+ * @x: the value. If it is unsigned type, it is converted to signed type first.
+ * char is treated as if it was signed (regardless of whether it really is)
+ * but the macro's return type is preserved as char.
*
- * Return: an absolute value of x. If x is 64-bit, macro's return type is s64,
- * otherwise it is signed long.
+ * Return: an absolute value of x.
*/
-#define abs(x) __builtin_choose_expr(sizeof(x) == sizeof(s64), ({ \
- s64 __x = (x); \
- (__x < 0) ? -__x : __x; \
- }), ({ \
- long ret; \
- if (sizeof(x) == sizeof(long)) { \
- long __x = (x); \
- ret = (__x < 0) ? -__x : __x; \
- } else { \
- int __x = (x); \
- ret = (__x < 0) ? -__x : __x; \
- } \
- ret; \
- }))
+#define abs(x) __abs_choose_expr(x, long long, \
+ __abs_choose_expr(x, long, \
+ __abs_choose_expr(x, int, \
+ __abs_choose_expr(x, short, \
+ __abs_choose_expr(x, char, \
+ __builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(x), char), \
+ (char)({ signed char __x = (x); __x<0?-__x:__x; }), \
+ ((void)0)))))))
+
+#define __abs_choose_expr(x, type, other) __builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(x), signed type) || \
+ __builtin_types_compatible_p(typeof(x), unsigned type), \
+ ({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
/**
* reciprocal_scale - "scale" a value into range [0, ep_ro)
@@ -255,6 +255,7 @@ extern long (*panic_blink)(int state);
__printf(1, 2)
void panic(const char *fmt, ...)
__noreturn __cold;
+void nmi_panic_self_stop(struct pt_regs *);
extern void oops_enter(void);
extern void oops_exit(void);
void print_oops_end_marker(void);
@@ -446,6 +447,33 @@ extern int sysctl_panic_on_stackoverflow;
extern bool crash_kexec_post_notifiers;
/*
+ * panic_cpu is used for synchronizing panic() and crash_kexec() execution. It
+ * holds a CPU number which is executing panic() currently. A value of
+ * PANIC_CPU_INVALID means no CPU has entered panic() or crash_kexec().
+ */
+extern atomic_t panic_cpu;
+#define PANIC_CPU_INVALID -1
+
+/*
+ * A variant of panic() called from NMI context. We return if we've already
+ * panicked on this CPU. If another CPU already panicked, loop in
+ * nmi_panic_self_stop() which can provide architecture dependent code such
+ * as saving register state for crash dump.
+ */
+#define nmi_panic(regs, fmt, ...) \
+do { \
+ int old_cpu, cpu; \
+ \
+ cpu = raw_smp_processor_id(); \
+ old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu); \
+ \
+ if (old_cpu == PANIC_CPU_INVALID) \
+ panic(fmt, ##__VA_ARGS__); \
+ else if (old_cpu != cpu) \
+ nmi_panic_self_stop(regs); \
+} while (0)
+
+/*
* Only to be used by arch init code. If the user over-wrote the default
* CONFIG_PANIC_TIMEOUT, honor it.
*/