6.13-stable review patch. If anyone has any objections, please let me know.
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From: Lucas De Marchi lucas.demarchi@intel.com
commit a9ab6591b45258b79af1cb66112fd9f83c8855da upstream.
Commit 70fb86a85dc9 ("drm/xe: Revert some changes that break a mesa debug tool") partially reverted some changes to workaround breakage caused to mesa tools. However, in doing so it also broke fetching the GuC log via debugfs since xe_print_blob_ascii85() simply bails out.
The fix is to avoid the extra newlines: the devcoredump interface is line-oriented and adding random newlines in the middle breaks it. If a tool is able to parse it by looking at the data and checking for chars that are out of the ascii85 space, it can still do so. A format change that breaks the line-oriented output on devcoredump however needs better coordination with existing tools.
v2: Add suffix description comment v3: Reword explanation of xe_print_blob_ascii85() calling drm_puts() in a loop
Reviewed-by: José Roberto de Souza jose.souza@intel.com Cc: John Harrison John.C.Harrison@Intel.com Cc: Julia Filipchuk julia.filipchuk@intel.com Cc: José Roberto de Souza jose.souza@intel.com Cc: stable@vger.kernel.org Fixes: 70fb86a85dc9 ("drm/xe: Revert some changes that break a mesa debug tool") Fixes: ec1455ce7e35 ("drm/xe/devcoredump: Add ASCII85 dump helper function") Link: https://patchwork.freedesktop.org/patch/msgid/20250123202307.95103-2-jose.so... Signed-off-by: Lucas De Marchi lucas.demarchi@intel.com (cherry picked from commit 2c95bbf5002776117a69caed3b31c10bf7341bec) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/xe/xe_devcoredump.c | 34 +++++++++++++--------------------- drivers/gpu/drm/xe/xe_devcoredump.h | 2 +- drivers/gpu/drm/xe/xe_guc_ct.c | 3 ++- drivers/gpu/drm/xe/xe_guc_log.c | 4 +++- 4 files changed, 19 insertions(+), 24 deletions(-)
--- a/drivers/gpu/drm/xe/xe_devcoredump.c +++ b/drivers/gpu/drm/xe/xe_devcoredump.c @@ -338,42 +338,34 @@ int xe_devcoredump_init(struct xe_device /** * xe_print_blob_ascii85 - print a BLOB to some useful location in ASCII85 * - * The output is split to multiple lines because some print targets, e.g. dmesg - * cannot handle arbitrarily long lines. Note also that printing to dmesg in - * piece-meal fashion is not possible, each separate call to drm_puts() has a - * line-feed automatically added! Therefore, the entire output line must be - * constructed in a local buffer first, then printed in one atomic output call. + * The output is split into multiple calls to drm_puts() because some print + * targets, e.g. dmesg, cannot handle arbitrarily long lines. These targets may + * add newlines, as is the case with dmesg: each drm_puts() call creates a + * separate line. * * There is also a scheduler yield call to prevent the 'task has been stuck for * 120s' kernel hang check feature from firing when printing to a slow target * such as dmesg over a serial port. * - * TODO: Add compression prior to the ASCII85 encoding to shrink huge buffers down. - * * @p: the printer object to output to * @prefix: optional prefix to add to output string + * @suffix: optional suffix to add at the end. 0 disables it and is + * not added to the output, which is useful when using multiple calls + * to dump data to @p * @blob: the Binary Large OBject to dump out * @offset: offset in bytes to skip from the front of the BLOB, must be a multiple of sizeof(u32) * @size: the size in bytes of the BLOB, must be a multiple of sizeof(u32) */ -void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix, +void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix, char suffix, const void *blob, size_t offset, size_t size) { const u32 *blob32 = (const u32 *)blob; char buff[ASCII85_BUFSZ], *line_buff; size_t line_pos = 0;
- /* - * Splitting blobs across multiple lines is not compatible with the mesa - * debug decoder tool. Note that even dropping the explicit '\n' below - * doesn't help because the GuC log is so big some underlying implementation - * still splits the lines at 512K characters. So just bail completely for - * the moment. - */ - return; - #define DMESG_MAX_LINE_LEN 800 -#define MIN_SPACE (ASCII85_BUFSZ + 2) /* 85 + "\n\0" */ + /* Always leave space for the suffix char and the \0 */ +#define MIN_SPACE (ASCII85_BUFSZ + 2) /* 85 + "<suffix>\0" */
if (size & 3) drm_printf(p, "Size not word aligned: %zu", size); @@ -405,7 +397,6 @@ void xe_print_blob_ascii85(struct drm_pr line_pos += strlen(line_buff + line_pos);
if ((line_pos + MIN_SPACE) >= DMESG_MAX_LINE_LEN) { - line_buff[line_pos++] = '\n'; line_buff[line_pos++] = 0;
drm_puts(p, line_buff); @@ -417,10 +408,11 @@ void xe_print_blob_ascii85(struct drm_pr } }
+ if (suffix) + line_buff[line_pos++] = suffix; + if (line_pos) { - line_buff[line_pos++] = '\n'; line_buff[line_pos++] = 0; - drm_puts(p, line_buff); }
--- a/drivers/gpu/drm/xe/xe_devcoredump.h +++ b/drivers/gpu/drm/xe/xe_devcoredump.h @@ -26,7 +26,7 @@ static inline int xe_devcoredump_init(st } #endif
-void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix, +void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix, char suffix, const void *blob, size_t offset, size_t size);
#endif --- a/drivers/gpu/drm/xe/xe_guc_ct.c +++ b/drivers/gpu/drm/xe/xe_guc_ct.c @@ -1700,7 +1700,8 @@ void xe_guc_ct_snapshot_print(struct xe_ snapshot->g2h_outstanding);
if (snapshot->ctb) - xe_print_blob_ascii85(p, "CTB data", snapshot->ctb, 0, snapshot->ctb_size); + xe_print_blob_ascii85(p, "CTB data", '\n', + snapshot->ctb, 0, snapshot->ctb_size); } else { drm_puts(p, "CT disabled\n"); } --- a/drivers/gpu/drm/xe/xe_guc_log.c +++ b/drivers/gpu/drm/xe/xe_guc_log.c @@ -211,8 +211,10 @@ void xe_guc_log_snapshot_print(struct xe remain = snapshot->size; for (i = 0; i < snapshot->num_chunks; i++) { size_t size = min(GUC_LOG_CHUNK_SIZE, remain); + const char *prefix = i ? NULL : "Log data"; + char suffix = i == snapshot->num_chunks - 1 ? '\n' : 0;
- xe_print_blob_ascii85(p, i ? NULL : "Log data", snapshot->copy[i], 0, size); + xe_print_blob_ascii85(p, prefix, suffix, snapshot->copy[i], 0, size); remain -= size; } }