crypto: tcrypt - avoid mapping from module image addresses

The output buffer in test_ahash_speed will point to an address located
within the tcrypt module image.
This causes problems when trying to DMA map the buffer.
For e.g. on ARM-based LS1021A, a page fault occurs within the
DMA API when trying to access the struct page returned by
virt_to_page(output):

insmod tcrypt.ko mode=403

testing speed of async sha1 (sha1-caam)
test  0 (   16 byte blocks,   16 bytes per update,   1 updates):
Unable to handle kernel paging request at virtual address f07e9080
pgd = e58d0e00
[f07e9080] *pgd=80000080007003, *pmd=00000000
Internal error: Oops: 206 [#1] SMP THUMB2
Modules linked in: tcrypt(+)
CPU: 1 PID: 1119 Comm: insmod Not tainted 4.2.0-rc1-256134-gbf433416 #1
Hardware name: Freescale LS1021A
task: ea063900 ti: e5a34000 task.ti: e5a34000
PC is at dma_cache_maint_page+0x38/0xd0
LR is at __dma_page_cpu_to_dev+0x15/0x64
pc : [<800155a0>]    lr : [<8001564d>]    psr: 000f0033
sp : e5a35ca0  ip : 8063df00  fp : f07e9080
r10: 00000cd0  r9 : 8063df00  r8 : 805a2f04
r7 : 0017f804  r6 : 00000002  r5 : ee7f9000  r4 : 00000014
r3 : 80612d40  r2 : 01ff0080  r1 : 00000380  r0 : ee7f9000
Flags: nzcv  IRQs on  FIQs on  Mode SVC_32  ISA Thumb  Segment user
Control: 70c5387d  Table: e58d0e00  DAC: 9b7ede70
Process insmod (pid: 1119, stack limit = 0xe5a34210)
Stack: (0xe5a35ca0 to 0xe5a36000)
[...]
[<800155a0>] (dma_cache_maint_page) from [<8001564d>] (__dma_page_cpu_to_dev+0x15/0x64)
[<8001564d>] (__dma_page_cpu_to_dev) from [<800156eb>] (arm_dma_map_page+0x1f/0x44)
[<800156eb>] (arm_dma_map_page) from [<802935e3>] (ahash_digest+0x35f/0x510)
[<802935e3>] (ahash_digest) from [<7f800d03>] (test_ahash_speed.constprop.6+0x24a/0x4e4 [tcrypt])
[<7f800d03>] (test_ahash_speed.constprop.6 [tcrypt]) from [<7f802fd5>] (do_test+0x1898/0x2058 [tcrypt])
[<7f802fd5>] (do_test [tcrypt]) from [<7f80802f>] (tcrypt_mod_init+0x2e/0x63 [tcrypt])
[<7f80802f>] (tcrypt_mod_init [tcrypt]) from [<80009517>] (do_one_initcall+0xb3/0x134)
[<80009517>] (do_one_initcall) from [<80351ec7>] (do_init_module+0x3b/0x13c)
[<80351ec7>] (do_init_module) from [<8005cc3f>] (load_module+0x97b/0x9dc)
[<8005cc3f>] (load_module) from [<8005cd8d>] (SyS_finit_module+0x35/0x3e)
[<8005cd8d>] (SyS_finit_module) from [<8000d101>] (ret_fast_syscall+0x1/0x4c)
Code: 1aba 0152 eb00 0b02 (5882) 0f92

addr2line -f -i -e vmlinux 800155a0
page_zonenum
include/linux/mm.h:728
page_zone
include/linux/mm.h:881
dma_cache_maint_page
arch/arm/mm/dma-mapping.c:822
Signed-off-by: Horia Geant? <horia.geanta@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/tcrypt.c

@@ -48,6 +48,8 @@
 #define ENCRYPT 1
 #define DECRYPT 0
 
+#define MAX_DIGEST_SIZE		64
+
 /*
  * return a string with the driver name
  */
@@ -950,7 +952,7 @@ static void test_ahash_speed(const char *algo, unsigned int secs,
 	struct tcrypt_result tresult;
 	struct ahash_request *req;
 	struct crypto_ahash *tfm;
-	static char output[1024];
+	char *output;
 	int i, ret;
 
 	tfm = crypto_alloc_ahash(algo, 0, 0);
@@ -963,9 +965,9 @@ static void test_ahash_speed(const char *algo, unsigned int secs,
 	printk(KERN_INFO "\ntesting speed of async %s (%s)\n", algo,
 			get_driver_name(crypto_ahash, tfm));
 
-	if (crypto_ahash_digestsize(tfm) > sizeof(output)) {
-		pr_err("digestsize(%u) > outputbuffer(%zu)\n",
-		       crypto_ahash_digestsize(tfm), sizeof(output));
+	if (crypto_ahash_digestsize(tfm) > MAX_DIGEST_SIZE) {
+		pr_err("digestsize(%u) > %d\n", crypto_ahash_digestsize(tfm),
+		       MAX_DIGEST_SIZE);
 		goto out;
 	}
 
@@ -980,6 +982,10 @@ static void test_ahash_speed(const char *algo, unsigned int secs,
 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
 				   tcrypt_complete, &tresult);
 
+	output = kmalloc(MAX_DIGEST_SIZE, GFP_KERNEL);
+	if (!output)
+		goto out_nomem;
+
 	for (i = 0; speed[i].blen != 0; i++) {
 		if (speed[i].blen > TVMEMSIZE * PAGE_SIZE) {
 			pr_err("template (%u) too big for tvmem (%lu)\n",
@@ -1006,6 +1012,9 @@ static void test_ahash_speed(const char *algo, unsigned int secs,
 		}
 	}
 
+	kfree(output);
+
+out_nomem:
 	ahash_request_free(req);
 
 out: