Subject: [PATCH] IBM Z DFLTCC: fix three data corruption issues

From: Ilya Leoshkevich <[email-masked]>
Date: Tue, 21 May 2019 13:25:23 +0200

Hello,

This patch fixes three bugs found during internal testing. It also adds
feature detection for sys/sdt.h, adds diagnostic output when hardware
decompression fails, and fixes formatting in a few places.

Best regards,
Ilya

---

* configure.ac (AC_CHECK_HEADERS_ONCE): Add feature detection for
sys/sdt.h probes.
* dfltcc.c (dfltcc_cc): Minor formatting improvements.
(HB_BITS): Remove.
(HB_SIZE): Likewise.
(dfltcc): Use sys/sdt.h feature detection.
(bi_load): New function.
(bi_close_block): Use bi_load.
(close_stream): Fix overwriting the End-of-block Symbol.
(dfltcc_deflate): Fix losing partial byte on flush.
Fix setting Block-Continuation Flag when DFLTCC-CMPR outputs 0 bits and
requests a retry.
Minor formatting improvements.
(dfltcc_inflate): Retry immediately if requested.
Print the hardware error code and flush the output buffer on error.
Minor formatting improvements.
* tests/hufts: Ignore the hardware error code.
---
 configure.ac |  2 +-
 dfltcc.c     | 63 +++++++++++++++++++++++++++++++++++-----------------
 tests/hufts  |  2 ++
 3 files changed, 46 insertions(+), 21 deletions(-)

diff --git a/configure.ac b/configure.ac
index 76ac26f..b4aea34 100644
--- a/configure.ac
+++ b/configure.ac
@@ -263,7 +263,7 @@ AC_SUBST([ASFLAGS_config])
 AC_ISC_POSIX
 AC_C_CONST
 AC_HEADER_STDC
-AC_CHECK_HEADERS_ONCE(fcntl.h limits.h memory.h time.h)
+AC_CHECK_HEADERS_ONCE(fcntl.h limits.h memory.h time.h sys/sdt.h)
 AC_CHECK_FUNCS_ONCE([chown fchmod fchown lstat siginterrupt])
 AC_HEADER_DIRENT
 AC_TYPE_SIGNAL
diff --git a/dfltcc.c b/dfltcc.c
index ba62968..6ad41a8 100644
--- a/dfltcc.c
+++ b/dfltcc.c
@@ -22,7 +22,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 
-#ifdef DFLTCC_USDT
+#ifdef HAVE_SYS_SDT_H
 # include <sys/sdt.h>
 #endif
 
@@ -39,11 +39,11 @@
 
 typedef enum
 {
- DFLTCC_CC_OK = 0,
- DFLTCC_CC_OP1_TOO_SHORT = 1,
- DFLTCC_CC_OP2_TOO_SHORT = 2,
- DFLTCC_CC_OP2_CORRUPT = 2,
- DFLTCC_CC_AGAIN = 3,
+  DFLTCC_CC_OK = 0,
+  DFLTCC_CC_OP1_TOO_SHORT = 1,
+  DFLTCC_CC_OP2_TOO_SHORT = 2,
+  DFLTCC_CC_OP2_CORRUPT = 2,
+  DFLTCC_CC_AGAIN = 3,
 } dfltcc_cc;
 
 #define DFLTCC_QAF 0
@@ -51,8 +51,6 @@ typedef enum
 #define DFLTCC_CMPR 2
 #define DFLTCC_XPND 4
 #define HBT_CIRCULAR (1 << 7)
-/* #define HB_BITS 15 */
-/* #define HB_SIZE (1 << HB_BITS) */
 #define DFLTCC_FACILITY 151
 #define DFLTCC_FMT0 0
 #define CVT_CRC32 0
@@ -180,12 +178,12 @@ dfltcc (int fn, void *param,
   int cc;
 
   __asm__ volatile (
-#ifdef DFLTCC_USDT
+#ifdef HAVE_SYS_SDT_H
                     STAP_PROBE_ASM (zlib, dfltcc_entry,
                                     STAP_PROBE_ASM_TEMPLATE (5))
 #endif
                     ".insn rrf,0xb9390000,%[r2],%[r4],%[hist],0\n"
-#ifdef DFLTCC_USDT
+#ifdef HAVE_SYS_SDT_H
                     STAP_PROBE_ASM (zlib, dfltcc_exit,
                                     STAP_PROBE_ASM_TEMPLATE (5))
 #endif
@@ -198,7 +196,7 @@ dfltcc (int fn, void *param,
                     : [r0] "r" (r0)
                       , [r1] "r" (r1)
                       , [hist] "r" (hist)
-#ifdef DFLTCC_USDT
+#ifdef HAVE_SYS_SDT_H
                       , STAP_PROBE_ASM_OPERANDS (5, r2, r3, r4, r5, hist)
 #endif
                     : "cc", "memory");
@@ -264,10 +262,16 @@ init_param (union aligned_dfltcc_param_v0 *ctx)
 }
 
 static void
-bi_close_block (struct dfltcc_param_v0 *param)
+bi_load (struct dfltcc_param_v0 *param)
 {
   bi_valid = param->sbb;
   bi_buf = bi_valid == 0 ? 0 : outbuf[outcnt] & ((1 << bi_valid) - 1);
+}
+
+static void
+bi_close_block (struct dfltcc_param_v0 *param)
+{
+  bi_load (param);
   send_bits (bi_reverse (param->eobs >> (15 - param->eobl), param->eobl),
              param->eobl);
   param->bcf = 0;
@@ -278,6 +282,7 @@ close_block (struct dfltcc_param_v0 *param)
 {
   bi_close_block (param);
   bi_windup ();
+  /* bi_windup has written out a possibly partial byte, fix up the position */
   param->sbb = (param->sbb + param->eobl) % 8;
   if (param->sbb != 0)
     {
@@ -291,6 +296,8 @@ close_stream (struct dfltcc_param_v0 *param)
 {
   if (param->bcf)
     bi_close_block (param);
+  else
+    bi_load (param);
   send_bits (1, 3); /* BFINAL=1, BTYPE=00 */
   bi_windup ();
   put_short (0x0000);
@@ -334,7 +341,16 @@ dfltcc_deflate (int pack_level)
     {
       /* Flush the output data.  */
       if (outcnt > OUTBUFSIZ - 8)
-        flush_outbuf ();
+        {
+          if (param->sbb == 0)
+            flush_outbuf ();
+          else
+            {
+              uch partial = outbuf[outcnt];
+              flush_outbuf ();
+              outbuf[outcnt] = partial;
+            }
+        }
 
       /* Close the block.  */
       if (param->bcf && total_in == block_threshold && !param->cf)
@@ -360,14 +376,16 @@ dfltcc_deflate (int pack_level)
         {
           if (total_in == 0 && block_threshold > 0)
             param->htt = HTT_FIXED;
-          else {
-            param->htt = HTT_DYNAMIC;
-            dfltcc_gdht (param);
-          }
+          else
+            {
+              param->htt = HTT_DYNAMIC;
+              dfltcc_gdht (param);
+            }
         }
 
       /* Compress inbuf into outbuf.  */
-      dfltcc_cmpr_xpnd (param, DFLTCC_CMPR);
+      while (dfltcc_cmpr_xpnd (param, DFLTCC_CMPR) == DFLTCC_CC_AGAIN)
+        ;
 
       /* Unmask the input data.  */
       insize += extra;
@@ -413,7 +431,9 @@ dfltcc_inflate (void)
         }
 
         /* Decompress inbuf into outbuf.  */
-        dfltcc_cc cc = dfltcc_cmpr_xpnd (param, DFLTCC_XPND);
+        dfltcc_cc cc;
+        while ((cc = dfltcc_cmpr_xpnd (param, DFLTCC_XPND)) == DFLTCC_CC_AGAIN)
+          ;
         if (cc == DFLTCC_CC_OK)
           {
             /* The entire deflate stream has been successfully decompressed.  */
@@ -422,6 +442,9 @@ dfltcc_inflate (void)
         if (cc == DFLTCC_CC_OP2_CORRUPT && param->oesc != 0)
           {
             /* The deflate stream is corrupted.  */
+            fprintf (stderr, "Operation-Ending-Supplemental Code 0x%x\n",
+                     param->oesc);
+            flush_outbuf ();
             return 2;
           }
         /* There must be more data to decompress.  */
@@ -430,7 +453,7 @@ dfltcc_inflate (void)
   if (param->sbb != 0)
     {
       /* The deflate stream has ended in the middle of a byte.  Go to
-        the next byte boundary, so that unzip can read CRC and length.  */
+         the next byte boundary, so that unzip can read CRC and length.  */
       inptr++;
     }
 
diff --git a/tests/hufts b/tests/hufts
index cd8368a..7ca22af 100755
--- a/tests/hufts
+++ b/tests/hufts
@@ -28,6 +28,7 @@ returns_ 1 gzip -dc "$abs_srcdir/hufts-segv.gz" > out 2> err || fail=1
 compare /dev/null out || fail=1
 
 sed 's/.*hufts-segv.gz: /...: /' err > k; mv k err || fail=1
+grep -v 'Operation-Ending-Supplemental Code' err > k; mv k err || fail=1
 compare exp err || fail=1
 
 printf '\037\213\010\000\060\060\060\060\060\060\144\000\000\000' > bug33501 \
@@ -35,6 +36,7 @@ printf '\037\213\010\000\060\060\060\060\060\060\144\000\000\000' > bug33501 \
 printf '\ngzip: stdin: invalid compressed data--format violated\n' >exp33501 \
   || framework_failure_
 returns_ 1 gzip -d <bug33501 >out33501 2> err33501 || fail=1
+grep -v 'Operation-Ending-Supplemental Code' err33501 > k; mv k err33501 || fail=1
 compare exp33501 err33501 || fail=1
 
 Exit $fail
-- 
2.21.0