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3e9b3112ec
Common approach to accessing register fields is to define
structures or sets of macros containing mask and shift pair.
Operations on the register are then performed as follows:
field = (reg >> shift) & mask;
reg &= ~(mask << shift);
reg |= (field & mask) << shift;
Defining shift and mask separately is tedious. Ivo van Doorn
came up with an idea of computing them at compilation time
based on a single shifted mask (later refined by Felix) which
can be used like this:
#define REG_FIELD 0x000ff000
field = FIELD_GET(REG_FIELD, reg);
reg &= ~REG_FIELD;
reg |= FIELD_PREP(REG_FIELD, field);
FIELD_{GET,PREP} macros take care of finding out what the
appropriate shift is based on compilation time ffs operation.
GENMASK can be used to define registers (which is usually
less error-prone and easier to match with datasheets).
This approach is the most convenient I've seen so to limit code
multiplication let's move the macros to a global header file.
Attempts to use static inlines instead of macros failed due
to false positive triggering of BUILD_BUG_ON()s, especially with
GCC < 6.0.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dinan Gunawardena <dinan.gunawardena@netronome.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
125 lines
3.9 KiB
C
125 lines
3.9 KiB
C
#ifndef _LINUX_BUG_H
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#define _LINUX_BUG_H
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#include <asm/bug.h>
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#include <linux/compiler.h>
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enum bug_trap_type {
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BUG_TRAP_TYPE_NONE = 0,
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BUG_TRAP_TYPE_WARN = 1,
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BUG_TRAP_TYPE_BUG = 2,
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};
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struct pt_regs;
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#ifdef __CHECKER__
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#define __BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)
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#define BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)
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#define BUILD_BUG_ON_ZERO(e) (0)
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#define BUILD_BUG_ON_NULL(e) ((void*)0)
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#define BUILD_BUG_ON_INVALID(e) (0)
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#define BUILD_BUG_ON_MSG(cond, msg) (0)
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#define BUILD_BUG_ON(condition) (0)
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#define BUILD_BUG() (0)
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#define MAYBE_BUILD_BUG_ON(cond) (0)
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#else /* __CHECKER__ */
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/* Force a compilation error if a constant expression is not a power of 2 */
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#define __BUILD_BUG_ON_NOT_POWER_OF_2(n) \
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BUILD_BUG_ON(((n) & ((n) - 1)) != 0)
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#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
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BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
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/* Force a compilation error if condition is true, but also produce a
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result (of value 0 and type size_t), so the expression can be used
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e.g. in a structure initializer (or where-ever else comma expressions
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aren't permitted). */
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#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
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#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
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/*
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* BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
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* expression but avoids the generation of any code, even if that expression
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* has side-effects.
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*/
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#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
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/**
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* BUILD_BUG_ON_MSG - break compile if a condition is true & emit supplied
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* error message.
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* @condition: the condition which the compiler should know is false.
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*
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* See BUILD_BUG_ON for description.
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*/
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#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
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/**
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* BUILD_BUG_ON - break compile if a condition is true.
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* @condition: the condition which the compiler should know is false.
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*
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* If you have some code which relies on certain constants being equal, or
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* some other compile-time-evaluated condition, you should use BUILD_BUG_ON to
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* detect if someone changes it.
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*
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* The implementation uses gcc's reluctance to create a negative array, but gcc
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* (as of 4.4) only emits that error for obvious cases (e.g. not arguments to
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* inline functions). Luckily, in 4.3 they added the "error" function
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* attribute just for this type of case. Thus, we use a negative sized array
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* (should always create an error on gcc versions older than 4.4) and then call
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* an undefined function with the error attribute (should always create an
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* error on gcc 4.3 and later). If for some reason, neither creates a
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* compile-time error, we'll still have a link-time error, which is harder to
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* track down.
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*/
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#ifndef __OPTIMIZE__
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#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
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#else
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#define BUILD_BUG_ON(condition) \
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BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
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#endif
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/**
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* BUILD_BUG - break compile if used.
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*
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* If you have some code that you expect the compiler to eliminate at
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* build time, you should use BUILD_BUG to detect if it is
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* unexpectedly used.
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*/
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#define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
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#define MAYBE_BUILD_BUG_ON(cond) \
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do { \
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if (__builtin_constant_p((cond))) \
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BUILD_BUG_ON(cond); \
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else \
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BUG_ON(cond); \
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} while (0)
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#endif /* __CHECKER__ */
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#ifdef CONFIG_GENERIC_BUG
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#include <asm-generic/bug.h>
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static inline int is_warning_bug(const struct bug_entry *bug)
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{
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return bug->flags & BUGFLAG_WARNING;
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}
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const struct bug_entry *find_bug(unsigned long bugaddr);
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enum bug_trap_type report_bug(unsigned long bug_addr, struct pt_regs *regs);
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/* These are defined by the architecture */
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int is_valid_bugaddr(unsigned long addr);
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#else /* !CONFIG_GENERIC_BUG */
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static inline enum bug_trap_type report_bug(unsigned long bug_addr,
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struct pt_regs *regs)
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{
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return BUG_TRAP_TYPE_BUG;
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}
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#endif /* CONFIG_GENERIC_BUG */
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#endif /* _LINUX_BUG_H */
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