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drm/i915: document range_overflows() and range_end_overflows() macros

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Document the macros in preparation for making them more generally
available.

Cc: Kees Cook <kees@kernel.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: linux-hardening@vger.kernel.org
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://lore.kernel.org/r/20250829174601.2163064-2-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Jani Nikula 2025-08-29 20:46:00 +03:00
parent 1e4c85167c
commit 59bf37add1
1 changed files with 46 additions and 0 deletions
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46
drivers/gpu/drm/i915/i915_utils.h
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@ -67,6 +67,18 @@ bool i915_error_injected(void);
drm_err(&(i915)->drm, fmt, ##__VA_ARGS__); \
})
/**
* range_overflows() - Check if a range is out of bounds
* @start: Start of the range.
* @size: Size of the range.
* @max: Exclusive upper boundary.
*
* A strict check to determine if the range [@start, @start + @size) is
* invalid with respect to the allowable range [0, @max). Any range
* starting at or beyond @max is considered an overflow, even if @size is 0.
*
* Returns: true if the range is out of bounds.
*/
#define range_overflows(start, size, max) ({ \
typeof(start) start__ = (start); \
typeof(size) size__ = (size); \
@ -76,9 +88,32 @@ bool i915_error_injected(void);
start__ >= max__ || size__ > max__ - start__; \
})
/**
* range_overflows_t() - Check if a range is out of bounds
* @type: Data type to use.
* @start: Start of the range.
* @size: Size of the range.
* @max: Exclusive upper boundary.
*
* Same as range_overflows() but forcing the parameters to @type.
*
* Returns: true if the range is out of bounds.
*/
#define range_overflows_t(type, start, size, max) \
range_overflows((type)(start), (type)(size), (type)(max))
/**
* range_end_overflows() - Check if a range's endpoint is out of bounds
* @start: Start of the range.
* @size: Size of the range.
* @max: Exclusive upper boundary.
*
* Checks only if the endpoint of a range (@start + @size) exceeds @max.
* Unlike range_overflows(), a zero-sized range at the boundary (@start == @max)
* is not considered an overflow. Useful for iterator-style checks.
*
* Returns: true if the endpoint exceeds the boundary.
*/
#define range_end_overflows(start, size, max) ({ \
typeof(start) start__ = (start); \
typeof(size) size__ = (size); \
@ -88,6 +123,17 @@ bool i915_error_injected(void);
start__ > max__ || size__ > max__ - start__; \
})
/**
* range_end_overflows_t() - Check if a range's endpoint is out of bounds
* @type: Data type to use.
* @start: Start of the range.
* @size: Size of the range.
* @max: Exclusive upper boundary.
*
* Same as range_end_overflows() but forcing the parameters to @type.
*
* Returns: true if the endpoint exceeds the boundary.
*/
#define range_end_overflows_t(type, start, size, max) \
range_end_overflows((type)(start), (type)(size), (type)(max))