s390/boot: add dfltcc= kernel command line parameter

Add the new kernel command line parameter 'dfltcc=' to configure s390
zlib hardware support.

Format: { on | off | def_only | inf_only | always }
on: s390 zlib hardware support for compression on
level 1 and decompression (default)
off: No s390 zlib hardware support
def_only: s390 zlib hardware support for deflate
only (compression on level 1)
inf_only: s390 zlib hardware support for inflate
only (decompression)
always: Same as 'on' but ignores the selected compression
level always using hardware support (used for debugging)

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Mikhail Zaslonko <[e-mail]>
Cc: Chris Mason <[e-mail]>
Cc: Christian Borntraeger <[e-mail]>
Cc: David Sterba <[e-mail]>
Cc: Eduard Shishkin <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Ilya Leoshkevich <[e-mail]>
Cc: Josef Bacik <[e-mail]>
Cc: Richard Purdie <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/admin-guide/kernel-parameters.txt

···
 			dump out devices still on the deferred probe list after
 			retrying.
 
+	dfltcc=		[HW,S390]
+			Format: { on | off | def_only | inf_only | always }
+			on:       s390 zlib hardware support for compression on
+			          level 1 and decompression (default)
+			off:      No s390 zlib hardware support
+			def_only: s390 zlib hardware support for deflate
+			          only (compression on level 1)
+			inf_only: s390 zlib hardware support for inflate
+			          only (decompression)
+			always:   Same as 'on' but ignores the selected compression
+			          level always using hardware support (used for debugging)
+
 	dhash_entries=	[KNL]
 			Set number of hash buckets for dentry cache.
 

arch/s390/boot/ipl_parm.c

···
 char __bootdata(early_command_line)[COMMAND_LINE_SIZE];
 struct ipl_parameter_block __bootdata_preserved(ipl_block);
 int __bootdata_preserved(ipl_block_valid);
+unsigned int __bootdata_preserved(zlib_dfltcc_support) = ZLIB_DFLTCC_FULL;
 
 unsigned long __bootdata(vmalloc_size) = VMALLOC_DEFAULT_SIZE;
 unsigned long __bootdata(memory_end);
···
 
 		if (!strcmp(param, "vmalloc") && val)
 			vmalloc_size = round_up(memparse(val, NULL), PAGE_SIZE);
+
+		if (!strcmp(param, "dfltcc")) {
+			if (!strcmp(val, "off"))
+				zlib_dfltcc_support = ZLIB_DFLTCC_DISABLED;
+			else if (!strcmp(val, "on"))
+				zlib_dfltcc_support = ZLIB_DFLTCC_FULL;
+			else if (!strcmp(val, "def_only"))
+				zlib_dfltcc_support = ZLIB_DFLTCC_DEFLATE_ONLY;
+			else if (!strcmp(val, "inf_only"))
+				zlib_dfltcc_support = ZLIB_DFLTCC_INFLATE_ONLY;
+			else if (!strcmp(val, "always"))
+				zlib_dfltcc_support = ZLIB_DFLTCC_FULL_DEBUG;
+		}
 
 		if (!strcmp(param, "noexec")) {
 			rc = kstrtobool(val, &enabled);

arch/s390/include/asm/setup.h

···
 	char command_line[ARCH_COMMAND_LINE_SIZE];	/* 0x10480 */
 };
 
+extern unsigned int zlib_dfltcc_support;
+#define ZLIB_DFLTCC_DISABLED		0
+#define ZLIB_DFLTCC_FULL		1
+#define ZLIB_DFLTCC_DEFLATE_ONLY	2
+#define ZLIB_DFLTCC_INFLATE_ONLY	3
+#define ZLIB_DFLTCC_FULL_DEBUG		4
+
 extern int noexec_disabled;
 extern int memory_end_set;
 extern unsigned long memory_end;

arch/s390/kernel/setup.c

···
 unsigned long __bootdata_preserved(__sdma);
 unsigned long __bootdata_preserved(__edma);
 unsigned long __bootdata_preserved(__kaslr_offset);
+unsigned int __bootdata_preserved(zlib_dfltcc_support);
+EXPORT_SYMBOL(zlib_dfltcc_support);
 
 unsigned long VMALLOC_START;
 EXPORT_SYMBOL(VMALLOC_START);

lib/zlib_dfltcc/dfltcc.c

···
     dfltcc_state->param.nt = 1;
 
     /* Initialize tuning parameters */
-    dfltcc_state->level_mask = DFLTCC_LEVEL_MASK;
+    if (zlib_dfltcc_support == ZLIB_DFLTCC_FULL_DEBUG)
+        dfltcc_state->level_mask = DFLTCC_LEVEL_MASK_DEBUG;
+    else
+        dfltcc_state->level_mask = DFLTCC_LEVEL_MASK;
     dfltcc_state->block_size = DFLTCC_BLOCK_SIZE;
     dfltcc_state->block_threshold = DFLTCC_FIRST_FHT_BLOCK_SIZE;
     dfltcc_state->dht_threshold = DFLTCC_DHT_MIN_SAMPLE_SIZE;

lib/zlib_dfltcc/dfltcc.h

···
  * Tuning parameters.
  */
 #define DFLTCC_LEVEL_MASK 0x2 /* DFLTCC compression for level 1 only */
+#define DFLTCC_LEVEL_MASK_DEBUG 0x3fe /* DFLTCC compression for all levels */
 #define DFLTCC_BLOCK_SIZE 1048576
 #define DFLTCC_FIRST_FHT_BLOCK_SIZE 4096
 #define DFLTCC_DHT_MIN_SAMPLE_SIZE 4096

lib/zlib_dfltcc/dfltcc_deflate.c

···
 #include "../zlib_deflate/defutil.h"
 #include "dfltcc_util.h"
 #include "dfltcc.h"
+#include <asm/setup.h>
 #include <linux/zutil.h>
 
 /*
···
 {
     deflate_state *state = (deflate_state *)strm->state;
     struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);
+
+    /* Check for kernel dfltcc command line parameter */
+    if (zlib_dfltcc_support == ZLIB_DFLTCC_DISABLED ||
+            zlib_dfltcc_support == ZLIB_DFLTCC_INFLATE_ONLY)
+        return 0;
 
     /* Unsupported compression settings */
     if (!dfltcc_are_params_ok(state->level, state->w_bits, state->strategy,

lib/zlib_dfltcc/dfltcc_inflate.c

···
 #include "../zlib_inflate/inflate.h"
 #include "dfltcc_util.h"
 #include "dfltcc.h"
+#include <asm/setup.h>
 #include <linux/zutil.h>
 
 /*
···
 {
     struct inflate_state *state = (struct inflate_state *)strm->state;
     struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);
+
+    /* Check for kernel dfltcc command line parameter */
+    if (zlib_dfltcc_support == ZLIB_DFLTCC_DISABLED ||
+            zlib_dfltcc_support == ZLIB_DFLTCC_DEFLATE_ONLY)
+        return 0;
 
     /* Unsupported compression settings */
     if (state->wbits != HB_BITS)

lib/zlib_dfltcc/dfltcc_util.h

···
 
 #include <linux/zutil.h>
 #include <asm/facility.h>
+#include <asm/setup.h>
 
 /*
  * C wrapper for the DEFLATE CONVERSION CALL instruction.
···
 
 static inline int is_dfltcc_enabled(void)
 {
-    return test_facility(DFLTCC_FACILITY);
+    return (zlib_dfltcc_support != ZLIB_DFLTCC_DISABLED &&
+            test_facility(DFLTCC_FACILITY));
 }
 
 char *oesc_msg(char *buf, int oesc);