From cfc57a18a3c5dc95d06db80bddd30015162c57d2 Mon Sep 17 00:00:00 2001 From: Jordan Crouse Date: Tue, 24 Jul 2018 10:33:20 -0600 Subject: [PATCH] drm: drm_printer: Add printer for devcoredump Add a drm printer suitable for use with the read callback for devcoredump or other suitable buffer based output format that isn't otherwise covered by seq_file. v2: Add improved documentation per Daniel Vetter Signed-off-by: Jordan Crouse Signed-off-by: Rob Clark --- drivers/gpu/drm/drm_print.c | 74 +++++++++++++++++++++++++++++++++++++ include/drm/drm_print.h | 65 ++++++++++++++++++++++++++++++++ 2 files changed, 139 insertions(+) diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c index b25f98f33f6c..03d1f98e5ac7 100644 --- a/drivers/gpu/drm/drm_print.c +++ b/drivers/gpu/drm/drm_print.c @@ -30,6 +30,80 @@ #include #include +void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf) +{ + struct drm_print_iterator *iterator = p->arg; + ssize_t len; + + if (!iterator->remain) + return; + + /* Figure out how big the string will be */ + len = snprintf(NULL, 0, "%pV", vaf); + + if (iterator->offset < iterator->start) { + char *buf; + ssize_t copy; + + if (iterator->offset + len <= iterator->start) { + iterator->offset += len; + return; + } + + /* Print the string into a temporary buffer */ + buf = kmalloc(len + 1, + GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY); + if (!buf) + return; + + snprintf(buf, len + 1, "%pV", vaf); + + copy = len - (iterator->start - iterator->offset); + + if (copy > iterator->remain) + copy = iterator->remain; + + /* Copy out the bit of the string that we need */ + memcpy(iterator->data, + buf + (iterator->start - iterator->offset), copy); + + iterator->offset = iterator->start + copy; + iterator->remain -= copy; + + kfree(buf); + } else { + char *buf; + ssize_t pos = iterator->offset - iterator->start; + + if (len < iterator->remain) { + snprintf(((char *) iterator->data) + pos, + iterator->remain, "%pV", vaf); + + iterator->offset += len; + iterator->remain -= len; + + return; + } + + /* Print the string into a temporary buffer */ + buf = kmalloc(len + 1, + GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY); + if (!buf) + return; + + snprintf(buf, len + 1, "%pV", vaf); + + /* Copy out the remaining bits */ + memcpy(iterator->data + pos, buf, iterator->remain); + + iterator->offset += iterator->remain; + iterator->remain = 0; + + kfree(buf); + } +} +EXPORT_SYMBOL(__drm_printfn_coredump); + void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf) { seq_printf(p->arg, "%pV", vaf); diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h index 767c90b654c5..e7570f93a21f 100644 --- a/include/drm/drm_print.h +++ b/include/drm/drm_print.h @@ -73,6 +73,7 @@ struct drm_printer { const char *prefix; }; +void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf); void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf); void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf); void __drm_printfn_debug(struct drm_printer *p, struct va_format *vaf); @@ -104,6 +105,70 @@ drm_vprintf(struct drm_printer *p, const char *fmt, va_list *va) #define drm_printf_indent(printer, indent, fmt, ...) \ drm_printf((printer), "%.*s" fmt, (indent), "\t\t\t\t\tX", ##__VA_ARGS__) +/** + * struct drm_print_iterator - local struct used with drm_printer_coredump + * @data: Pointer to the devcoredump output buffer + * @start: The offset within the buffer to start writing + * @remain: The number of bytes to write for this iteration + */ +struct drm_print_iterator { + void *data; + ssize_t start; + ssize_t remain; + /* private: */ + ssize_t offset; +}; + +/** + * drm_coredump_printer - construct a &drm_printer that can output to a buffer + * from the read function for devcoredump + * @iter: A pointer to a struct drm_print_iterator for the read instance + * + * This wrapper extends drm_printf() to work with a dev_coredumpm() callback + * function. The passed in drm_print_iterator struct contains the buffer + * pointer, size and offset as passed in from devcoredump. + * + * For example:: + * + * void coredump_read(char *buffer, loff_t offset, size_t count, + * void *data, size_t datalen) + * { + * struct drm_print_iterator iter; + * struct drm_printer p; + * + * iter.data = buffer; + * iter.start = offset; + * iter.remain = count; + * + * p = drm_coredump_printer(&iter); + * + * drm_printf(p, "foo=%d\n", foo); + * } + * + * void makecoredump(...) + * { + * ... + * dev_coredumpm(dev, THIS_MODULE, data, 0, GFP_KERNEL, + * coredump_read, ...) + * } + * + * RETURNS: + * The &drm_printer object + */ +static inline struct drm_printer +drm_coredump_printer(struct drm_print_iterator *iter) +{ + struct drm_printer p = { + .printfn = __drm_printfn_coredump, + .arg = iter, + }; + + /* Set the internal offset of the iterator to zero */ + iter->offset = 0; + + return p; +} + /** * drm_seq_file_printer - construct a &drm_printer that outputs to &seq_file * @f: the &struct seq_file to output to -- 2.30.2