From 53369581dc0c68a5700ed51e1660f44c4b2bb524 Mon Sep 17 00:00:00 2001 From: Matthew Brost Date: Thu, 1 Aug 2024 08:41:17 -0700 Subject: drm/printer: Allow NULL data in devcoredump printer We want to determine the size of the devcoredump before writing it out. To that end, we will run the devcoredump printer with NULL data to get the size, alloc data based on the generated offset, then run the devcorecump again with a valid data pointer to print. This necessitates not writing data to the data pointer on the initial pass, when it is NULL. v5: - Better commit message (Jonathan) - Add kerenl doc with examples (Jani) Cc: Maarten Lankhorst Acked-by: Maarten Lankhorst Signed-off-by: Matthew Brost Reviewed-by: Jonathan Cavitt Link: https://patchwork.freedesktop.org/patch/msgid/20240801154118.2547543-3-matthew.brost@intel.com --- include/drm/drm_print.h | 54 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 53 insertions(+), 1 deletion(-) (limited to 'include/drm') diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h index 5d9dff5149c9..d2676831d765 100644 --- a/include/drm/drm_print.h +++ b/include/drm/drm_print.h @@ -221,7 +221,8 @@ drm_vprintf(struct drm_printer *p, const char *fmt, va_list *va) /** * struct drm_print_iterator - local struct used with drm_printer_coredump - * @data: Pointer to the devcoredump output buffer + * @data: Pointer to the devcoredump output buffer, can be NULL if using + * drm_printer_coredump to determine size of devcoredump * @start: The offset within the buffer to start writing * @remain: The number of bytes to write for this iteration */ @@ -266,6 +267,57 @@ struct drm_print_iterator { * coredump_read, ...) * } * + * The above example has a time complexity of O(N^2), where N is the size of the + * devcoredump. This is acceptable for small devcoredumps but scales poorly for + * larger ones. + * + * Another use case for drm_coredump_printer is to capture the devcoredump into + * a saved buffer before the dev_coredump() callback. This involves two passes: + * one to determine the size of the devcoredump and another to print it to a + * buffer. Then, in dev_coredump(), copy from the saved buffer into the + * devcoredump read buffer. + * + * For example:: + * + * char *devcoredump_saved_buffer; + * + * ssize_t __coredump_print(char *buffer, ssize_t count, ...) + * { + * struct drm_print_iterator iter; + * struct drm_printer p; + * + * iter.data = buffer; + * iter.start = 0; + * iter.remain = count; + * + * p = drm_coredump_printer(&iter); + * + * drm_printf(p, "foo=%d\n", foo); + * ... + * return count - iter.remain; + * } + * + * void coredump_print(...) + * { + * ssize_t count; + * + * count = __coredump_print(NULL, INT_MAX, ...); + * devcoredump_saved_buffer = kvmalloc(count, GFP_KERNEL); + * __coredump_print(devcoredump_saved_buffer, count, ...); + * } + * + * void coredump_read(char *buffer, loff_t offset, size_t count, + * void *data, size_t datalen) + * { + * ... + * memcpy(buffer, devcoredump_saved_buffer + offset, count); + * ... + * } + * + * The above example has a time complexity of O(N*2), where N is the size of the + * devcoredump. This scales better than the previous example for larger + * devcoredumps. + * * RETURNS: * The &drm_printer object */ -- cgit v1.2.3 From decbfaf06db05fa1f9b33149ebb3c145b44e878f Mon Sep 17 00:00:00 2001 From: Nirmoy Das Date: Fri, 16 Aug 2024 15:51:53 +0200 Subject: drm/ttm: Add a flag to allow drivers to skip clear-on-free MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add TTM_TT_FLAG_CLEARED_ON_FREE, which DRM drivers can set before releasing backing stores if they want to skip clear-on-free. Cc: Matthew Auld Cc: Thomas Hellström Suggested-by: Christian König Reviewed-by: Christian König Link: https://patchwork.freedesktop.org/patch/msgid/20240816135154.19678-1-nirmoy.das@intel.com Signed-off-by: Nirmoy Das --- include/drm/ttm/ttm_tt.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'include/drm') diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h index 2b9d856ff388..cfaf49de2419 100644 --- a/include/drm/ttm/ttm_tt.h +++ b/include/drm/ttm/ttm_tt.h @@ -85,6 +85,9 @@ struct ttm_tt { * fault handling abuses the DMA api a bit and dma_map_attrs can't be * used to assure pgprot always matches. * + * TTM_TT_FLAG_CLEARED_ON_FREE: Set this if a drm driver handles + * clearing backing store + * * TTM_TT_FLAG_PRIV_POPULATED: TTM internal only. DO NOT USE. This is * set by TTM after ttm_tt_populate() has successfully returned, and is * then unset when TTM calls ttm_tt_unpopulate(). @@ -94,8 +97,9 @@ struct ttm_tt { #define TTM_TT_FLAG_EXTERNAL BIT(2) #define TTM_TT_FLAG_EXTERNAL_MAPPABLE BIT(3) #define TTM_TT_FLAG_DECRYPTED BIT(4) +#define TTM_TT_FLAG_CLEARED_ON_FREE BIT(5) -#define TTM_TT_FLAG_PRIV_POPULATED BIT(5) +#define TTM_TT_FLAG_PRIV_POPULATED BIT(6) uint32_t page_flags; /** @num_pages: Number of pages in the page array. */ uint32_t num_pages; -- cgit v1.2.3 From 789e51597d33ec0053b029127d797d86c0d857eb Mon Sep 17 00:00:00 2001 From: Nirmoy Das Date: Wed, 28 Aug 2024 10:36:35 +0200 Subject: Revert "drm/ttm: Add a flag to allow drivers to skip clear-on-free" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Remove TTM_TT_FLAG_CLEARED_ON_FREE now that XE stopped using this flag. This reverts commit decbfaf06db05fa1f9b33149ebb3c145b44e878f. Cc: Christian König Cc: Himal Prasad Ghimiray Cc: Lucas De Marchi Cc: Matthew Auld Cc: Matthew Brost Cc: Thomas Hellström Signed-off-by: Nirmoy Das Reviewed-by: Thomas Hellström Link: https://patchwork.freedesktop.org/patch/msgid/20240828083635.23601-2-nirmoy.das@intel.com Signed-off-by: Lucas De Marchi --- include/drm/ttm/ttm_tt.h | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) (limited to 'include/drm') diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h index cfaf49de2419..2b9d856ff388 100644 --- a/include/drm/ttm/ttm_tt.h +++ b/include/drm/ttm/ttm_tt.h @@ -85,9 +85,6 @@ struct ttm_tt { * fault handling abuses the DMA api a bit and dma_map_attrs can't be * used to assure pgprot always matches. * - * TTM_TT_FLAG_CLEARED_ON_FREE: Set this if a drm driver handles - * clearing backing store - * * TTM_TT_FLAG_PRIV_POPULATED: TTM internal only. DO NOT USE. This is * set by TTM after ttm_tt_populate() has successfully returned, and is * then unset when TTM calls ttm_tt_unpopulate(). @@ -97,9 +94,8 @@ struct ttm_tt { #define TTM_TT_FLAG_EXTERNAL BIT(2) #define TTM_TT_FLAG_EXTERNAL_MAPPABLE BIT(3) #define TTM_TT_FLAG_DECRYPTED BIT(4) -#define TTM_TT_FLAG_CLEARED_ON_FREE BIT(5) -#define TTM_TT_FLAG_PRIV_POPULATED BIT(6) +#define TTM_TT_FLAG_PRIV_POPULATED BIT(5) uint32_t page_flags; /** @num_pages: Number of pages in the page array. */ uint32_t num_pages; -- cgit v1.2.3