ACPI: APEI: Better fix to avoid spamming the console with old error logs

commit c3481b6b75b4797657838f44028fd28226ab48e0 upstream.

The fix in commit 3f8dec116210 ("ACPI/APEI: Limit printable size of BERT
table data") does not work as intended on systems where the BIOS has a
fixed size block of memory for the BERT table, relying on s/w to quit
when it finds a record with estatus->block_status == 0. On these systems
all errors are suppressed because the check:

	if (region_len < ACPI_BERT_PRINT_MAX_LEN)

always fails.

New scheme skips individual CPER records that are too large, and also
limits the total number of records that will be printed to 5.

Fixes: 3f8dec116210 ("ACPI/APEI: Limit printable size of BERT table data")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/acpi/apei/bert.c b/drivers/acpi/apei/bert.c
index 598fd19b65fa489d1cc4d44da8db7ee072612e1a..45973aa6e06d487815acaf48a4c3d90dcede7a90 100644 (file)
--- a/drivers/acpi/apei/bert.c
+++ b/drivers/acpi/apei/bert.c
@@ -29,16 +29,26 @@
 
 #undef pr_fmt
 #define pr_fmt(fmt) "BERT: " fmt
+
+#define ACPI_BERT_PRINT_MAX_RECORDS 5
 #define ACPI_BERT_PRINT_MAX_LEN 1024
 
 static int bert_disable;
 
+/*
+ * Print "all" the error records in the BERT table, but avoid huge spam to
+ * the console if the BIOS included oversize records, or too many records.
+ * Skipping some records here does not lose anything because the full
+ * data is available to user tools in:
+ *     /sys/firmware/acpi/tables/data/BERT
+ */
 static void __init bert_print_all(struct acpi_bert_region *region,
                                  unsigned int region_len)
 {
        struct acpi_hest_generic_status *estatus =
                (struct acpi_hest_generic_status *)region;
        int remain = region_len;
+       int printed = 0, skipped = 0;
        u32 estatus_len;
 
        while (remain >= sizeof(struct acpi_bert_region)) {
@@ -46,24 +56,26 @@ static void __init bert_print_all(struct acpi_bert_region *region,
                if (remain < estatus_len) {
                        pr_err(FW_BUG "Truncated status block (length: %u).\n",
                               estatus_len);
-                       return;
+                       break;
                }
 
                /* No more error records. */
                if (!estatus->block_status)
-                       return;
+                       break;
 
                if (cper_estatus_check(estatus)) {
                        pr_err(FW_BUG "Invalid error record.\n");
-                       return;
+                       break;
                }
 
-               pr_info_once("Error records from previous boot:\n");
-               if (region_len < ACPI_BERT_PRINT_MAX_LEN)
+               if (estatus_len < ACPI_BERT_PRINT_MAX_LEN &&
+                   printed < ACPI_BERT_PRINT_MAX_RECORDS) {
+                       pr_info_once("Error records from previous boot:\n");
                        cper_estatus_print(KERN_INFO HW_ERR, estatus);
-               else
-                       pr_info_once("Max print length exceeded, table data is available at:\n"
-                                    "/sys/firmware/acpi/tables/data/BERT");
+                       printed++;
+               } else {
+                       skipped++;
+               }
 
                /*
                 * Because the boot error source is "one-time polled" type,
@@ -75,6 +87,9 @@ static void __init bert_print_all(struct acpi_bert_region *region,
                estatus = (void *)estatus + estatus_len;
                remain -= estatus_len;
        }
+
+       if (skipped)
+               pr_info(HW_ERR "Skipped %d error records\n", skipped);
 }
 
 static int __init setup_bert_disable(char *str)