[Intel-xe] [PATCH] drm/xe: Introduce xe_ASSERT macros
Jani Nikula
jani.nikula at intel.com
Tue Aug 8 07:45:26 UTC 2023
On Mon, 07 Aug 2023, Michal Wajdeczko <michal.wajdeczko at intel.com> wrote:
> As we are moving away from the controversial XE_BUG_ON macro,
> relying just on WARN_ON or drm_err does not cover the cases
> where we want to annotate functions with additional detailed
> debug checks to assert that all prerequisites are satisfied,
> without paying footprint or performance penalty on non-debug
> builds, where all misuses introduced during code integration
> were already fixed.
>
> Introduce family of xe_ASSERT macros that try to follow classic
> assert() utility and can be compiled out on non-debug builds.
>
> Macros are based on drm_WARN, but unlikely to origin, disallow
> use in expressions since we will compile that code out.
Final bikeshedding... thought of the inconsistency between:
- drm_WARN_ON <-> xe_ASSERT
- drm_WARN <-> xe_ASSERT_MSG
and wondering if xe_ASSERT_ON and xe_ASSERT would be more in line.
*shrug*
Either way, this looks fine.
BR,
Jani.
>
> As we are operating on the xe pointers, we can print additional
> information about the device, like tile or GT identifier, that
> is not available from generic WARN report:
>
> [ ] xe 0000:00:02.0: [drm] Assertion `true == false` failed!
> platform: 1 subplatform: 1
> graphics: Xe_LP 12.0 step B0
> media: Xe_M 12.0 step B0
> display: enabled step D0
> tile: 0 VRAM 0 B
> GT: 0 type 1
>
> [ ] xe 0000:b3:00.0: [drm] Assertion `true == false` failed!
> platform: 7 subplatform: 3
> graphics: Xe_HPG 12.55 step A1
> media: Xe_HPM 12.55 step A1
> display: disabled step **
> tile: 0 VRAM 14.0 GiB
> GT: 0 type 1
>
> [ ] WARNING: CPU: 0 PID: 2687 at drivers/gpu/drm/xe/xe_device.c:281 xe_device_probe+0x374/0x520 [xe]
> [ ] RIP: 0010:xe_device_probe+0x374/0x520 [xe]
> [ ] Call Trace:
> [ ] ? __warn+0x7b/0x160
> [ ] ? xe_device_probe+0x374/0x520 [xe]
> [ ] ? report_bug+0x1c3/0x1d0
> [ ] ? handle_bug+0x42/0x70
> [ ] ? exc_invalid_op+0x14/0x70
> [ ] ? asm_exc_invalid_op+0x16/0x20
> [ ] ? xe_device_probe+0x374/0x520 [xe]
> [ ] ? xe_device_probe+0x374/0x520 [xe]
> [ ] xe_pci_probe+0x6e3/0x950 [xe]
> [ ] ? lockdep_hardirqs_on+0xc7/0x140
> [ ] pci_device_probe+0x9e/0x160
> [ ] really_probe+0x19d/0x400
>
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Oded Gabbay <ogabbay at kernel.org>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Matthew Brost <matthew.brost at intel.com>
> ---
> drivers/gpu/drm/xe/xe_assert.h | 160 +++++++++++++++++++++++++++++++++
> 1 file changed, 160 insertions(+)
> create mode 100644 drivers/gpu/drm/xe/xe_assert.h
>
> diff --git a/drivers/gpu/drm/xe/xe_assert.h b/drivers/gpu/drm/xe/xe_assert.h
> new file mode 100644
> index 000000000000..7ea295b7091c
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_assert.h
> @@ -0,0 +1,160 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2023 Intel Corporation
> + */
> +
> +#ifndef __XE_ASSERT_H__
> +#define __XE_ASSERT_H__
> +
> +#include <linux/string_helpers.h>
> +#include <drm/drm_print.h>
> +#include "xe_device_types.h"
> +#include "xe_step.h"
> +
> +/**
> + * DOC: Xe ASSERTs
> + *
> + * While Xe driver aims to be simpler than legacy i915 driver it is still
> + * complex enough that some changes introduced while adding new functionality
> + * could break the existing code.
> + *
> + * Adding &drm_WARN or &drm_err to catch unwanted programming usage could lead
> + * to undesired increased driver footprint and may impact production driver
> + * performance as this additional code will be always present.
> + *
> + * To allow annotate functions with additional detailed debug checks to assert
> + * that all prerequisites are satisfied, without worrying about footprint or
> + * performance penalty on production builds where all potential misuses
> + * introduced during code integration were already fixed, we introduce family
> + * of ASSERT macros that try to follow classic assert() utility and can be
> + * compiled out on non-debug builds:
> + *
> + * * &xe_ASSERT
> + * * &xe_tile_ASSERT
> + * * &xe_gt_ASSERT
> + *
> + * These macros are based on &drm_WARN, but unlikely to the origin, we disallow
> + * use of them in an expressions since we will compile that code out.
> + *
> + * Note that these macros shall not be used to cover known gaps in the
> + * implementation, for such cases use &drm_WARN or &drm_err and provide valid
> + * safe fallback.
> + *
> + * Below code shows how asserts could help in debug to catch unplanned use::
> + *
> + * static void one_igfx(struct xe_device *xe)
> + * {
> + * xe_ASSERT(xe, xe->info.is_dgfx == false);
> + * xe_ASSERT(xe, xe->info.tile_count == 1);
> + * }
> + *
> + * static void two_dgfx(struct xe_device *xe)
> + * {
> + * xe_ASSERT(xe, xe->info.is_dgfx);
> + * xe_ASSERT(xe, xe->info.tile_count == 2);
> + * }
> + *
> + * void foo(struct xe_device *xe)
> + * {
> + * if (xe->info.dgfx)
> + * return two_dgfx(xe);
> + * return one_igfx(xe);
> + * }
> + */
> +
> +#if IS_ENABLED(CONFIG_DRM_XE_DEBUG)
> +#define __XE_ASSERT_MSG(xe, condition, msg, arg...) ({ \
> + (void)drm_WARN(&(xe)->drm, !(condition), "[" DRM_NAME "] Assertion `%s` failed!\n" msg, \
> + __stringify(condition), ## arg); \
> +})
> +#else
> +#define __XE_ASSERT_MSG(xe, condition, msg, arg...) ({ \
> + typecheck(struct xe_device *, xe); \
> + BUILD_BUG_ON_INVALID(condition); \
> +})
> +#endif
> +
> +/**
> + * xe_ASSERT - warn if condition is false when debugging.
> + * @xe: the &struct xe_device pointer to which &condition applies
> + * @condition: condition to check
> + *
> + * xe_ASSERT() uses &drm_WARN to emit a warning and print additional information
> + * that could be read from the &xe pointer if provided &condition is false.
> + *
> + * Contrary to &drm_WARN, xe_ASSERT() is effective only on debug builds
> + * (&CONFIG_DRM_XE_DEBUG must be enabled) and cannot be used in expressions
> + * or as a condition.
> + *
> + * See `Xe ASSERTs`_ for general usage guidelines.
> + */
> +#define xe_ASSERT(xe, condition) xe_ASSERT_MSG((xe), condition, "")
> +#define xe_ASSERT_MSG(xe, condition, msg, arg...) ({ \
> + struct xe_device *__xe = (xe); \
> + __XE_ASSERT_MSG(__xe, condition, \
> + "platform: %d subplatform: %d\n" \
> + "graphics: %s %u.%u step %s\n" \
> + "media: %s %u.%u step %s\n" \
> + "display: %s step %s\n" \
> + msg, \
> + __xe->info.platform, __xe->info.subplatform, \
> + __xe->info.graphics_name, \
> + __xe->info.graphics_verx100 / 100, \
> + __xe->info.graphics_verx100 % 100, \
> + xe_step_name(__xe->info.step.graphics), \
> + __xe->info.media_name, \
> + __xe->info.media_verx100 / 100, \
> + __xe->info.media_verx100 % 100, \
> + xe_step_name(__xe->info.step.media), \
> + str_enabled_disabled(__xe->info.enable_display), \
> + xe_step_name(__xe->info.step.display), \
> + ## arg); \
> +})
> +
> +/**
> + * xe_tile_ASSERT - warn if condition is false when debugging.
> + * @tile: the &struct xe_tile pointer to which &condition applies
> + * @condition: condition to check
> + *
> + * xe_tile_ASSERT() uses &drm_WARN to emit a warning and print additional
> + * information that could be read from the &tile pointer if provided &condition
> + * is false.
> + *
> + * Contrary to &drm_WARN, xe_tile_ASSERT() is effective only on debug builds
> + * (&CONFIG_DRM_XE_DEBUG must be enabled) and cannot be used in expressions
> + * or as a condition.
> + *
> + * See `Xe ASSERTs`_ for general usage guidelines.
> + */
> +#define xe_tile_ASSERT(tile, condition) xe_tile_ASSERT_MSG((tile), condition, "")
> +#define xe_tile_ASSERT_MSG(tile, condition, msg, arg...) ({ \
> + struct xe_tile *__tile = (tile); \
> + char __buf[10]; \
> + xe_ASSERT_MSG(tile_to_xe(__tile), condition, "tile: %u VRAM %s\n" msg, \
> + __tile->id, ({ string_get_size(__tile->mem.vram.actual_physical_size, 1, \
> + STRING_UNITS_2, __buf, sizeof(__buf)); __buf; }), ## arg); \
> +})
> +
> +/**
> + * xe_gt_ASSERT - warn if condition is false when debugging.
> + * @gt: the &struct xe_gt pointer to which &condition applies
> + * @condition: condition to check
> + *
> + * xe_gt_ASSERT() uses &drm_WARN to emit a warning and print additional
> + * information that could be safetely read from the > pointer if provided
> + * &condition is false.
> + *
> + * Contrary to &drm_WARN, xe_gt_ASSERT() is effective only on debug builds
> + * (&CONFIG_DRM_XE_DEBUG must be enabled) and cannot be used in expressions
> + * or as a condition.
> + *
> + * See `Xe ASSERTs`_ for general usage guidelines.
> + */
> +#define xe_gt_ASSERT(gt, condition) xe_gt_ASSERT_MSG((gt), condition, "")
> +#define xe_gt_ASSERT_MSG(gt, condition, msg, arg...) ({ \
> + struct xe_gt *__gt = (gt); \
> + xe_tile_ASSERT_MSG(gt_to_tile(__gt), condition, "GT: %u type %d\n" msg, \
> + __gt->info.id, __gt->info.type, ## arg); \
> +})
> +
> +#endif /* __XE_ASSERT_H__ */
--
Jani Nikula, Intel Open Source Graphics Center
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