kmsg - kmsg_dump() use iterator to receive log buffer content

Provide an iterator to receive the log buffer content, and convert all
kmsg_dump() users to it.

The structured data in the kmsg buffer now contains binary data, which
should no longer be copied verbatim to the kmsg_dump() users.

The iterator should provide reliable access to the buffer data, and also
supports proper log line-aware chunking of data while iterating.

Signed-off-by: Kay Sievers <kay@vrfy.org>
Tested-by: Tony Luck <tony.luck@intel.com>
Reported-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Tested-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

6 files changed, 258 insertions, 137 deletions

diff --git a/arch/powerpc/platforms/pseries/nvram.c b/arch/powerpc/platforms/pseries/nvram.c
index 36f957f31842..8733a86ad52e 100644
--- a/arch/powerpc/platforms/pseries/nvram.c
+++ b/arch/powerpc/platforms/pseries/nvram.c
@@ -68,9 +68,7 @@ static const char *pseries_nvram_os_partitions[] = {
 };
 
 static void oops_to_nvram(struct kmsg_dumper *dumper,
-                enum kmsg_dump_reason reason,
-                const char *old_msgs, unsigned long old_len,
-                const char *new_msgs, unsigned long new_len);
+                          enum kmsg_dump_reason reason);
 
 static struct kmsg_dumper nvram_kmsg_dumper = {
         .dump = oops_to_nvram
@@ -504,28 +502,6 @@ int __init pSeries_nvram_init(void)
 }
 
 /*
- * Try to capture the last capture_len bytes of the printk buffer.  Return
- * the amount actually captured.
- */
-static size_t capture_last_msgs(const char *old_msgs, size_t old_len,
-                                const char *new_msgs, size_t new_len,
-                                char *captured, size_t capture_len)
-{
-        if (new_len >= capture_len) {
-                memcpy(captured, new_msgs + (new_len - capture_len),
-                                                                capture_len);
-                return capture_len;
-        } else {
-                /* Grab the end of old_msgs. */
-                size_t old_tail_len = min(old_len, capture_len - new_len);
-                memcpy(captured, old_msgs + (old_len - old_tail_len),
-                                                                old_tail_len);
-                memcpy(captured + old_tail_len, new_msgs, new_len);
-                return old_tail_len + new_len;
-        }
-}
-
-/*
  * Are we using the ibm,rtas-log for oops/panic reports?  And if so,
  * would logging this oops/panic overwrite an RTAS event that rtas_errd
  * hasn't had a chance to read and process?  Return 1 if so, else 0.
@@ -541,27 +517,6 @@ static int clobbering_unread_rtas_event(void)
                                                 NVRAM_RTAS_READ_TIMEOUT);
 }
 
-/* Squeeze out each line's <n> severity prefix. */
-static size_t elide_severities(char *buf, size_t len)
-{
-        char *in, *out, *buf_end = buf + len;
-        /* Assume a <n> at the very beginning marks the start of a line. */
-        int newline = 1;
-
-        in = out = buf;
-        while (in < buf_end) {
-                if (newline && in+3 <= buf_end &&
-                                *in == '<' && isdigit(in[1]) && in[2] == '>') {
-                        in += 3;
-                        newline = 0;
-                } else {
-                        newline = (*in == '\n');
-                        *out++ = *in++;
-                }
-        }
-        return out - buf;
-}
-
 /* Derived from logfs_compress() */
 static int nvram_compress(const void *in, void *out, size_t inlen,
                                                         size_t outlen)
@@ -619,9 +574,7 @@ static int zip_oops(size_t text_len)
  * partition.  If that's too much, go back and capture uncompressed text.
  */
 static void oops_to_nvram(struct kmsg_dumper *dumper,
-                enum kmsg_dump_reason reason,
-                const char *old_msgs, unsigned long old_len,
-                const char *new_msgs, unsigned long new_len)
+                          enum kmsg_dump_reason reason)
 {
         static unsigned int oops_count = 0;
         static bool panicking = false;
@@ -660,14 +613,14 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
                 return;
 
         if (big_oops_buf) {
-                text_len = capture_last_msgs(old_msgs, old_len,
-                        new_msgs, new_len, big_oops_buf, big_oops_buf_sz);
-                text_len = elide_severities(big_oops_buf, text_len);
+                kmsg_dump_get_buffer(dumper, false,
+                                     big_oops_buf, big_oops_buf_sz, &text_len);
                 rc = zip_oops(text_len);
         }
         if (rc != 0) {
-                text_len = capture_last_msgs(old_msgs, old_len,
-                                new_msgs, new_len, oops_data, oops_data_sz);
+                kmsg_dump_rewind(dumper);
+                kmsg_dump_get_buffer(dumper, true,
+                                     oops_data, oops_data_sz, &text_len);
                 err_type = ERR_TYPE_KERNEL_PANIC;
                 *oops_len = (u16) text_len;
         }
diff --git a/arch/x86/platform/mrst/early_printk_mrst.c b/arch/x86/platform/mrst/early_printk_mrst.c
index 3c6e328483c7..028454f0c3a5 100644
--- a/arch/x86/platform/mrst/early_printk_mrst.c
+++ b/arch/x86/platform/mrst/early_printk_mrst.c
@@ -110,19 +110,16 @@ static struct kmsg_dumper dw_dumper;
 static int dumper_registered;
 
 static void dw_kmsg_dump(struct kmsg_dumper *dumper,
-                        enum kmsg_dump_reason reason,
-                        const char *s1, unsigned long l1,
-                        const char *s2, unsigned long l2)
+                         enum kmsg_dump_reason reason)
 {
-        int i;
+        static char line[1024];
+        size_t len;
 
         /* When run to this, we'd better re-init the HW */
         mrst_early_console_init();
 
-        for (i = 0; i < l1; i++)
-                early_mrst_console.write(&early_mrst_console, s1 + i, 1);
-        for (i = 0; i < l2; i++)
-                early_mrst_console.write(&early_mrst_console, s2 + i, 1);
+        while (kmsg_dump_get_line(dumper, true, line, sizeof(line), &len))
+                early_mrst_console.write(&early_mrst_console, line, len);
 }
 
 /* Set the ratio rate to 115200, 8n1, IRQ disabled */
diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index ae36d7e1e913..551e316e4454 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -304,32 +304,17 @@ static void find_next_position(struct mtdoops_context *cxt)
 }
 
 static void mtdoops_do_dump(struct kmsg_dumper *dumper,
-                enum kmsg_dump_reason reason, const char *s1, unsigned long l1,
-                const char *s2, unsigned long l2)
+                            enum kmsg_dump_reason reason)
 {
         struct mtdoops_context *cxt = container_of(dumper,
                         struct mtdoops_context, dump);
-        unsigned long s1_start, s2_start;
-        unsigned long l1_cpy, l2_cpy;
-        char *dst;
-
-        if (reason != KMSG_DUMP_OOPS &&
-            reason != KMSG_DUMP_PANIC)
-                return;
 
         /* Only dump oopses if dump_oops is set */
         if (reason == KMSG_DUMP_OOPS && !dump_oops)
                 return;
 
-        dst = cxt->oops_buf + MTDOOPS_HEADER_SIZE; /* Skip the header */
-        l2_cpy = min(l2, record_size - MTDOOPS_HEADER_SIZE);
+        kmsg_dump_get_buffer(dumper, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE,
+                             record_size - MTDOOPS_HEADER_SIZE, NULL);