[kvm-unit-tests PATCH v4 0/3] s390x: SCLP Unit test

[kvm-unit-tests PATCH v4 0/3] s390x: SCLP Unit test

[Claudio Imbrenda]

This patchset contains some minor cleanup, some preparatory work and
then the SCLP unit test itself.

The unit test checks the following:
    
    * Correctly ignoring instruction bits that should be ignored
    * Privileged instruction check
    * Check for addressing exceptions
    * Specification exceptions:
      - SCCB size less than 8
      - SCCB unaligned
      - SCCB overlaps prefix or lowcore
      - SCCB address higher than 2GB
    * Return codes for
      - Invalid command
      - SCCB too short (but at least 8)
      - SCCB page boundary violation

v3 -> v4
* export sclp_setup_int instead of copying it
* add more comments
* rename some more variables to improve readability
* improve the prefix test
* improved the invalid address test
* addressed further comments received during review
v2 -> v3
* generally improved the naming of variables
* added and fixed comments
* renamed test_one_run to test_one_simple
* added some const where needed
* addresed many more small comments received during review
v1 -> v2
* fix many small issues that came up during the first round of reviews
* add comments to each function
* use a static buffer for the SCCP template when used

Claudio Imbrenda (3):
  s390x: export sclp_setup_int
  s390x: sclp: add service call instruction wrapper
  s390x: SCLP unit test

 s390x/Makefile           |   1 +
 lib/s390x/asm/arch_def.h |  13 ++
 lib/s390x/sclp.h         |   1 +
 lib/s390x/sclp.c         |   9 +-
 s390x/sclp.c             | 465 +++++++++++++++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg      |   3 +
 6 files changed, 485 insertions(+), 7 deletions(-)
 create mode 100644 s390x/sclp.c

-- 
2.7.4

[kvm-unit-tests PATCH v4 1/3] s390x: export sclp_setup_int

[Claudio Imbrenda]

Export sclp_setup_int() so that it can be used from outside.

Needed for an upocoming unit test.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 lib/s390x/sclp.h | 1 +
 lib/s390x/sclp.c | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
index 6d40fb7..675f07e 100644
--- a/lib/s390x/sclp.h
+++ b/lib/s390x/sclp.h
@@ -265,6 +265,7 @@ typedef struct ReadEventData {
 } __attribute__((packed)) ReadEventData;
 
 extern char _sccb[];
+void sclp_setup_int(void);
 void sclp_handle_ext(void);
 void sclp_wait_busy(void);
 void sclp_mark_busy(void);
diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
index 7798f04..123b639 100644
--- a/lib/s390x/sclp.c
+++ b/lib/s390x/sclp.c
@@ -45,7 +45,7 @@ static void mem_init(phys_addr_t mem_end)
 	page_alloc_ops_enable();
 }
 
-static void sclp_setup_int(void)
+void sclp_setup_int(void)
 {
 	uint64_t mask;
 
-- 
2.7.4

Re: [kvm-unit-tests PATCH v4 1/3] s390x: export sclp_setup_int

[Thomas Huth]

On 19/11/2019 10.53, Claudio Imbrenda wrote:
> Export sclp_setup_int() so that it can be used from outside.
> 
> Needed for an upocoming unit test.
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>  lib/s390x/sclp.h | 1 +
>  lib/s390x/sclp.c | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
> index 6d40fb7..675f07e 100644
> --- a/lib/s390x/sclp.h
> +++ b/lib/s390x/sclp.h
> @@ -265,6 +265,7 @@ typedef struct ReadEventData {
>  } __attribute__((packed)) ReadEventData;
>  
>  extern char _sccb[];
> +void sclp_setup_int(void);
>  void sclp_handle_ext(void);
>  void sclp_wait_busy(void);
>  void sclp_mark_busy(void);
> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
> index 7798f04..123b639 100644
> --- a/lib/s390x/sclp.c
> +++ b/lib/s390x/sclp.c
> @@ -45,7 +45,7 @@ static void mem_init(phys_addr_t mem_end)
>  	page_alloc_ops_enable();
>  }
>  
> -static void sclp_setup_int(void)
> +void sclp_setup_int(void)
>  {
>  	uint64_t mask;

Reviewed-by: Thomas Huth <thuth@redhat.com>

Re: [kvm-unit-tests PATCH v4 1/3] s390x: export sclp_setup_int

[Janosch Frank]

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On 11/19/19 10:53 AM, Claudio Imbrenda wrote:
> Export sclp_setup_int() so that it can be used from outside.
> 
> Needed for an upocoming unit test.
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> ---
>  lib/s390x/sclp.h | 1 +
>  lib/s390x/sclp.c | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
> index 6d40fb7..675f07e 100644
> --- a/lib/s390x/sclp.h
> +++ b/lib/s390x/sclp.h
> @@ -265,6 +265,7 @@ typedef struct ReadEventData {
>  } __attribute__((packed)) ReadEventData;
>  
>  extern char _sccb[];
> +void sclp_setup_int(void);
>  void sclp_handle_ext(void);
>  void sclp_wait_busy(void);
>  void sclp_mark_busy(void);
> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
> index 7798f04..123b639 100644
> --- a/lib/s390x/sclp.c
> +++ b/lib/s390x/sclp.c
> @@ -45,7 +45,7 @@ static void mem_init(phys_addr_t mem_end)
>  	page_alloc_ops_enable();
>  }
>  
> -static void sclp_setup_int(void)
> +void sclp_setup_int(void)
>  {
>  	uint64_t mask;
>  
> 



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Re: [kvm-unit-tests PATCH v4 1/3] s390x: export sclp_setup_int

[Janosch Frank]

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On 11/19/19 10:53 AM, Claudio Imbrenda wrote:
> Export sclp_setup_int() so that it can be used from outside.

... so that it can be used in tests / outside of lib/s390x/sclp.c

Choose one

> 
> Needed for an upocoming unit test.

upocoming?

> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>  lib/s390x/sclp.h | 1 +
>  lib/s390x/sclp.c | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
> index 6d40fb7..675f07e 100644
> --- a/lib/s390x/sclp.h
> +++ b/lib/s390x/sclp.h
> @@ -265,6 +265,7 @@ typedef struct ReadEventData {
>  } __attribute__((packed)) ReadEventData;
>  
>  extern char _sccb[];
> +void sclp_setup_int(void);
>  void sclp_handle_ext(void);
>  void sclp_wait_busy(void);
>  void sclp_mark_busy(void);
> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
> index 7798f04..123b639 100644
> --- a/lib/s390x/sclp.c
> +++ b/lib/s390x/sclp.c
> @@ -45,7 +45,7 @@ static void mem_init(phys_addr_t mem_end)
>  	page_alloc_ops_enable();
>  }
>  
> -static void sclp_setup_int(void)
> +void sclp_setup_int(void)
>  {
>  	uint64_t mask;
>  
> 



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[kvm-unit-tests PATCH v4 2/3] s390x: sclp: add service call instruction wrapper

[Claudio Imbrenda]

Add a wrapper for the service call instruction, and use it for SCLP
interactions instead of using inline assembly everywhere.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
---
 lib/s390x/asm/arch_def.h | 13 +++++++++++++
 lib/s390x/sclp.c         |  7 +------
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index 96cca2e..b3caff6 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -269,4 +269,17 @@ static inline int stsi(void *addr, int fc, int sel1, int sel2)
 	return cc;
 }
 
+static inline int servc(uint32_t command, unsigned long sccb)
+{
+	int cc;
+
+	asm volatile(
+		"       .insn   rre,0xb2200000,%1,%2\n"  /* servc %1,%2 */
+		"       ipm     %0\n"
+		"       srl     %0,28"
+		: "=&d" (cc) : "d" (command), "a" (sccb)
+		: "cc", "memory");
+	return cc;
+}
+
 #endif
diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
index 123b639..4054d0e 100644
--- a/lib/s390x/sclp.c
+++ b/lib/s390x/sclp.c
@@ -116,12 +116,7 @@ int sclp_service_call(unsigned int command, void *sccb)
 	int cc;
 
 	sclp_setup_int();
-	asm volatile(
-		"       .insn   rre,0xb2200000,%1,%2\n"  /* servc %1,%2 */
-		"       ipm     %0\n"
-		"       srl     %0,28"
-		: "=&d" (cc) : "d" (command), "a" (__pa(sccb))
-		: "cc", "memory");
+	cc = servc(command, __pa(sccb));
 	sclp_wait_busy();
 	if (cc == 3)
 		return -1;
-- 
2.7.4

[kvm-unit-tests PATCH v4 3/3] s390x: SCLP unit test

[Claudio Imbrenda]

SCLP unit test. Testing the following:

* Correctly ignoring instruction bits that should be ignored
* Privileged instruction check
* Check for addressing exceptions
* Specification exceptions:
  - SCCB size less than 8
  - SCCB unaligned
  - SCCB overlaps prefix or lowcore
  - SCCB address higher than 2GB
* Return codes for
  - Invalid command
  - SCCB too short (but at least 8)
  - SCCB page boundary violation

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 s390x/Makefile      |   1 +
 s390x/sclp.c        | 465 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg |   3 +
 3 files changed, 469 insertions(+)
 create mode 100644 s390x/sclp.c

diff --git a/s390x/Makefile b/s390x/Makefile
index 3744372..ddb4b48 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -16,6 +16,7 @@ tests += $(TEST_DIR)/diag288.elf
 tests += $(TEST_DIR)/stsi.elf
 tests += $(TEST_DIR)/skrf.elf
 tests += $(TEST_DIR)/smp.elf
+tests += $(TEST_DIR)/sclp.elf
 tests_binary = $(patsubst %.elf,%.bin,$(tests))
 
 all: directories test_cases test_cases_binary
diff --git a/s390x/sclp.c b/s390x/sclp.c
new file mode 100644
index 0000000..aeb0b04
--- /dev/null
+++ b/s390x/sclp.c
@@ -0,0 +1,465 @@
+/*
+ * Service Call tests
+ *
+ * Copyright (c) 2019 IBM Corp
+ *
+ * Authors:
+ *  Claudio Imbrenda <imbrenda@linux.ibm.com>
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#include <libcflat.h>
+#include <asm/page.h>
+#include <asm/asm-offsets.h>
+#include <asm/interrupt.h>
+#include <sclp.h>
+
+#define PGM_NONE	1
+#define PGM_BIT_SPEC	(1ULL << PGM_INT_CODE_SPECIFICATION)
+#define PGM_BIT_ADDR	(1ULL << PGM_INT_CODE_ADDRESSING)
+#define PGM_BIT_PRIV	(1ULL << PGM_INT_CODE_PRIVILEGED_OPERATION)
+#define MKPTR(x) ((void *)(uint64_t)(x))
+
+/* two pages of scratch memory to be used for some of the tests */
+static uint8_t pagebuf[PAGE_SIZE * 2] __attribute__((aligned(PAGE_SIZE * 2)));
+/* used as prefix when testing prefix access, to guarantee that prefix != 0 */
+static uint8_t prefix_buf[PAGE_SIZE * 2] __attribute__((aligned(PAGE_SIZE * 2)));
+/* SCCB template used to */
+static uint8_t sccb_template[PAGE_SIZE];
+/* the valid command code to use for getting SCP information */
+static uint32_t valid_code;
+/* points to lowcore (real address 0) */
+static struct lowcore *lc;
+
+/**
+ * Perform one service call, handling exceptions and interrupts.
+ */
+static int sclp_service_call_test(unsigned int command, void *sccb)
+{
+	int cc;
+
+	sclp_mark_busy();
+	sclp_setup_int();
+	cc = servc(command, __pa(sccb));
+	if (lc->pgm_int_code) {
+		sclp_handle_ext();
+		return 0;
+	}
+	if (!cc)
+		sclp_wait_busy();
+	return cc;
+}
+
+/**
+ * Perform one test at the given address, optionally using the SCCB template,
+ * checking for the expected program interrupts and return codes.
+ *
+ * The parameter buf_len indicates the number of bytes of the template that
+ * should be copied to the test address, and should be 0 when the test
+ * address is invalid, in which case nothing is copied.
+ *
+ * The template is used to simplify tests where the same buffer content is
+ * used many times in a row, at different addresses.
+ *
+ * Returns true in case of success or false in case of failure
+ */
+static bool test_one_sccb(uint32_t cmd, uint8_t *addr, uint16_t buf_len, uint64_t exp_pgm, uint16_t exp_rc)
+{
+	SCCBHeader *h = (SCCBHeader *)addr;
+	int res, pgm;
+
+	/* Copy the template to the test address if needed */
+	if (buf_len)
+		memcpy(addr, sccb_template, buf_len);
+	expect_pgm_int();
+	/* perform the actuall call */
+	res = sclp_service_call_test(cmd, h);
+	if (res) {
+		report_info("SCLP not ready (command %#x, address %p, cc %d)", cmd, addr, res);
+		return false;
+	}
+	pgm = clear_pgm_int();
+	/* Check if the program exception was one of the expected ones */
+	if (!((1ULL << pgm) & exp_pgm)) {
+		report_info("First failure at addr %p, buf_len %d, cmd %#x, pgm code %d",
+				addr, buf_len, cmd, pgm);
+		return false;
+	}
+	/* Check if the response code is the one expected */
+	if (exp_rc && exp_rc != h->response_code) {
+		report_info("First failure at addr %p, buf_len %d, cmd %#x, resp code %#x",
+				addr, buf_len, cmd, h->response_code);
+		return false;
+	}
+	return true;
+}
+
+/**
+ * Wrapper for test_one_sccb to set up a simple SCCB template.
+ *
+ * The parameter sccb_len indicates the value that will be saved in the SCCB
+ * length field of the SCCB, buf_len indicates the number of bytes of
+ * template that need to be copied to the actual test address. In many cases
+ * it's enough to clear/copy the first 8 bytes of the buffer, while the SCCB
+ * itself can be larger.
+ *
+ * Returns true in case of success or false in case of failure
+ */
+static bool test_one_simple(uint32_t cmd, uint8_t *addr, uint16_t sccb_len,
+			uint16_t buf_len, uint64_t exp_pgm, uint16_t exp_rc)
+{
+	memset(sccb_template, 0, sizeof(sccb_template));
+	((SCCBHeader *)sccb_template)->length = sccb_len;
+	return test_one_sccb(cmd, addr, buf_len, exp_pgm, exp_rc);
+}
+
+/**
+ * Test SCCB lengths < 8.
+ */
+static void test_sccb_too_short(void)
+{
+	int len;
+
+	for (len = 0; len < 8; len++)
+		if (!test_one_simple(valid_code, pagebuf, len, 8, PGM_BIT_SPEC, 0))
+			break;
+
+	report("SCCB too short", len == 8);
+}
+
+/**
+ * Test SCCBs that are not 64-bit aligned.
+ */
+static void test_sccb_unaligned(void)
+{
+	int offset;
+
+	for (offset = 1; offset < 8; offset++)
+		if (!test_one_simple(valid_code, offset + pagebuf, 8, 8, PGM_BIT_SPEC, 0))
+			break;
+	report("SCCB unaligned", offset == 8);
+}
+
+/**
+ * Test SCCBs whose address is in the lowcore or prefix area.
+ */
+static void test_sccb_prefix(void)
+{
+	uint8_t scratch[2 * PAGE_SIZE];
+	uint32_t prefix, new_prefix;
+	int offset;
+
+	/*
+	 * copy the current lowcore to the future new location, otherwise we
+	 * will not have a valid lowcore after setting the new prefix.
+	 */
+	memcpy(prefix_buf, 0, 2 * PAGE_SIZE);
+	/* save the current prefix (it's probably going to be 0) */
+	asm volatile("stpx %0" : "=Q" (prefix));
+	/*
+	 * save the current content of absolute pages 0 and 1, so we can
+	 * restore them after we trash them later on
+	 */
+	memcpy(scratch, (void *)(intptr_t)prefix, 2 * PAGE_SIZE);
+	/* set the new prefix to prefix_buf */
+	new_prefix = (uint32_t)(intptr_t)prefix_buf;
+	asm volatile("spx %0" : : "Q" (new_prefix) : "memory");
+
+	/*
+	 * testing with SCCB addresses in the lowcore; since we can't
+	 * actually trash the lowcore (unsurprisingly, things break if we
+	 * do), this will be a read-only test.
+	 */
+	for (offset = 0; offset < 2 * PAGE_SIZE; offset += 8)
+		if (!test_one_sccb(valid_code, MKPTR(offset), 0, PGM_BIT_SPEC, 0))
+			break;
+	report("SCCB low pages", offset == 2 * PAGE_SIZE);
+
+	/*
+	 * this will trash the contents of the two pages at absolute
+	 * address 0; we will need to restore them later.
+	 */
+	for (offset = 0; offset < 2 * PAGE_SIZE; offset += 8)
+		if (!test_one_simple(valid_code, MKPTR(new_prefix + offset), 8, 8, PGM_BIT_SPEC, 0))
+			break;
+	report("SCCB prefix pages", offset == 2 * PAGE_SIZE);
+
+	/* restore the previous contents of absolute pages 0 and 1 */
+	memcpy(prefix_buf, 0, 2 * PAGE_SIZE);
+	/* restore the prefix to the original value */
+	asm volatile("spx %0" : : "Q" (prefix) : "memory");
+}
+
+/**
+ * Test SCCBs that are above 2GB. If outside of memory, an addressing
+ * exception is also allowed.
+ */
+static void test_sccb_high(void)
+{
+	SCCBHeader *h = (SCCBHeader *)pagebuf;
+	uintptr_t a[33 * 4 * 2 + 2];	/* for the list of addresses to test */
+
+	uint64_t maxram;
+	int i, pgm, len = 0;
+
+	h->length = 8;
+	/* addresses with 1 bit set in the first 33 bits */
+	for (i = 0; i < 33; i++)
+		a[len++] = 1UL << (i + 31);
+	/* addresses with 2 consecutive bits set in the first 33 bits */
+	for (i = 0; i < 33; i++)
+		a[len++] = 3UL << (i + 31);
+	/* addresses with all bits set in bits 0..N */
+	for (i = 0; i < 33; i++)
+		a[len++] = 0xffffffff80000000UL << i;
+	/* addresses with all bits set in bits N..33 */
+	a[len++] = 0x80000000;
+	for (i = 1; i < 33; i++, len++)
+		a[len] = a[len - 1] | (1UL << (i + 31));
+	/* all the addresses above, but adding the offset of a valid buffer */
+	for (i = 0; i < len; i++)
+		a[len + i] = a[i] + (intptr_t)h;
+	len += i;
+	/* two more hand-crafted addresses */
+	a[len++] = 0xdeadbeef00000000;
+	a[len++] = 0xdeaddeadbeef0000;
+
+	maxram = get_ram_size();
+	for (i = 0; i < len; i++) {
+		pgm = PGM_BIT_SPEC | (a[i] >= maxram ? PGM_BIT_ADDR : 0);
+		if (!test_one_sccb(valid_code, (void *)a[i], 0, pgm, 0))
+			break;
+	}
+	report("SCCB high addresses", i == len);
+}
+
+/**
+ * Test invalid commands, both invalid command detail codes and valid
+ * ones with invalid command class code.
+ */
+static void test_inval(void)
+{
+	const uint16_t res = SCLP_RC_INVALID_SCLP_COMMAND;
+	uint32_t cmd;
+	int i;
+
+	report_prefix_push("Invalid command");
+	for (i = 0; i < 65536; i++) {
+		cmd = 0xdead0000 | i;
+		if (!test_one_simple(cmd, pagebuf, PAGE_SIZE, PAGE_SIZE, PGM_NONE, res))
+			break;
+	}
+	report("Command detail code", i == 65536);
+
+	for (i = 0; i < 256; i++) {
+		cmd = (valid_code & ~0xff) | i;
+		if (cmd == valid_code)
+			continue;
+		if (!test_one_simple(cmd, pagebuf, PAGE_SIZE, PAGE_SIZE, PGM_NONE, res))
+			break;
+	}
+	report("Command class code", i == 256);
+	report_prefix_pop();
+}
+
+
+/**
+ * Test short SCCBs (but larger than 8).
+ */
+static void test_short(void)
+{
+	const uint16_t res = SCLP_RC_INSUFFICIENT_SCCB_LENGTH;
+	int len;
+
+	for (len = 8; len < 144; len++)
+		if (!test_one_simple(valid_code, pagebuf, len, len, PGM_NONE, res))
+			break;
+	report("Insufficient SCCB length (Read SCP info)", len == 144);
+
+	for (len = 8; len < 40; len++)
+		if (!test_one_simple(SCLP_READ_CPU_INFO, pagebuf, len, len, PGM_NONE, res))
+			break;
+	report("Insufficient SCCB length (Read CPU info)", len == 40);
+}
+
+/**
+ * Test SCCB page boundary violations.
+ */
+static void test_boundary(void)
+{
+	const uint32_t cmd = SCLP_CMD_WRITE_EVENT_DATA;
+	const uint16_t res = SCLP_RC_SCCB_BOUNDARY_VIOLATION;
+	WriteEventData *sccb = (WriteEventData *)sccb_template;
+	int len, offset;
+
+	memset(sccb_template, 0, sizeof(sccb_template));
+	sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
+	for (len = 32; len <= 4096; len++) {
+		offset = len & 7 ? len & ~7 : len - 8;
+		for (offset = 4096 - offset; offset < 4096; offset += 8) {
+			sccb->h.length = len;
+			if (!test_one_sccb(cmd, offset + pagebuf, len, PGM_NONE, res))
+				goto out;
+		}
+	}
+out:
+	report("SCCB page boundary violation", len > 4096 && offset == 4096);
+}
+
+/**
+ * Test excessively long SCCBs.
+ */
+static void test_toolong(void)
+{
+	const uint32_t cmd = SCLP_CMD_WRITE_EVENT_DATA;
+	const uint16_t res = SCLP_RC_SCCB_BOUNDARY_VIOLATION;
+	WriteEventData *sccb = (WriteEventData *)sccb_template;
+	int len;
+
+	memset(sccb_template, 0, sizeof(sccb_template));
+	sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
+	for (len = 4097; len < 8192; len++) {
+		sccb->h.length = len;
+		if (!test_one_sccb(cmd, pagebuf, PAGE_SIZE, PGM_NONE, res))
+			break;
+	}
+	report("SCCB bigger than 4k", len == 8192);
+}
+
+/**
+ * Test privileged operation.
+ */
+static void test_priv(void)
+{
+	SCCBHeader *h = (SCCBHeader *)pagebuf;
+
+	report_prefix_push("Privileged operation");
+	h->length = 8;
+	expect_pgm_int();
+	enter_pstate();
+	servc(valid_code, __pa(h));
+	check_pgm_int_code(PGM_INT_CODE_PRIVILEGED_OPERATION);
+	report_prefix_pop();
+}
+
+/**
+ * Test addressing exceptions. We need to test SCCB addresses between the
+ * end of available memory and 2GB, because after 2GB a specification
+ * exception is also allowed.
+ * Only applicable if the VM has less than 2GB of memory
+ */
+static void test_addressing(void)
+{
+	unsigned long i, maxram = get_ram_size();
+
+	/* the VM has more than 2GB of memory */
+	if (maxram >= 0x80000000) {
+		report_skip("Invalid SCCB address");
+		return;
+	}
+	/* test all possible valid addresses immediately after the end of memory
+	 * up to 64KB after the end of memory
+	 */
+	for (i = 0; i < 0x10000 && i + maxram < 0x80000000; i += 8)
+		if (!test_one_sccb(valid_code, MKPTR(i + maxram), 0, PGM_BIT_ADDR, 0))
+			goto out;
+	/* test more addresses until we reach 1MB after end of memory;
+	 * increment by a prime number (times 8) in order to test all
+	 * possible valid offsets inside pages
+	 */
+	for (; i < 0x100000 && i + maxram < 0x80000000 ; i += 808)
+		if (!test_one_sccb(valid_code, MKPTR(i + maxram), 0, PGM_BIT_ADDR, 0))
+			goto out;
+	/* test the remaining addresses until we reach address 2GB;
+	 * increment by a prime number (times 8) in order to test all
+	 * possible valid offsets inside pages
+	 */
+	for (; i < 0x80000000; i += 800024)
+		if (!test_one_sccb(valid_code, MKPTR(i + maxram), 0, PGM_BIT_ADDR, 0))
+			goto out;
+out:
+	report("Invalid SCCB address", i >= 0x80000000);
+}
+
+/**
+ * Test some bits in the instruction format that are specified to be ignored.
+ */
+static void test_instbits(void)
+{
+	SCCBHeader *h = (SCCBHeader *)pagebuf;
+	int cc;
+
+	expect_pgm_int();
+	sclp_mark_busy();
+	h->length = 8;
+	sclp_setup_int();
+
+	asm volatile(
+		"       .insn   rre,0xb2204200,%1,%2\n"  /* servc %1,%2 */
+		"       ipm     %0\n"
+		"       srl     %0,28"
+		: "=&d" (cc) : "d" (valid_code), "a" (__pa(pagebuf))
+		: "cc", "memory");
+	if (lc->pgm_int_code) {
+		sclp_handle_ext();
+		cc = 1;
+	} else if (!cc)
+		sclp_wait_busy();
+	report("Instruction format ignored bits", cc == 0);
+}
+
+/**
+ * Find a valid SCLP command code; not all codes are always allowed, and
+ * probing should be performed in the right order.
+ */
+static void find_valid_sclp_code(void)
+{
+	const unsigned int commands[] = { SCLP_CMDW_READ_SCP_INFO_FORCED,
+					  SCLP_CMDW_READ_SCP_INFO };
+	SCCBHeader *h = (SCCBHeader *)pagebuf;
+	int i, cc;
+
+	for (i = 0; i < ARRAY_SIZE(commands); i++) {
+		sclp_mark_busy();
+		memset(h, 0, sizeof(*h));
+		h->length = 4096;
+
+		valid_code = commands[i];
+		cc = sclp_service_call(commands[i], h);
+		if (cc)
+			break;
+		if (h->response_code == SCLP_RC_NORMAL_READ_COMPLETION)
+			return;
+		if (h->response_code != SCLP_RC_INVALID_SCLP_COMMAND)
+			break;
+	}
+	valid_code = 0;
+	report_abort("READ_SCP_INFO failed");
+}
+
+int main(void)
+{
+	report_prefix_push("sclp");
+	find_valid_sclp_code();
+
+	/* Test some basic things */
+	test_instbits();
+	test_priv();
+	test_addressing();
+
+	/* Test the specification exceptions */
+	test_sccb_too_short();
+	test_sccb_unaligned();
+	test_sccb_prefix();
+	test_sccb_high();
+
+	/* Test the expected response codes */
+	test_inval();
+	test_short();
+	test_boundary();
+	test_toolong();
+
+	return report_summary();
+}
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index f1b07cd..75e3d37 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -75,3 +75,6 @@ file = stsi.elf
 [smp]
 file = smp.elf
 extra_params =-smp 2
+
+[sclp]
+file = sclp.elf
-- 
2.7.4

Re: [kvm-unit-tests PATCH v4 3/3] s390x: SCLP unit test

[Thomas Huth]

On 19/11/2019 10.53, Claudio Imbrenda wrote:
> SCLP unit test. Testing the following:
> 
> * Correctly ignoring instruction bits that should be ignored
> * Privileged instruction check
> * Check for addressing exceptions
> * Specification exceptions:
>   - SCCB size less than 8
>   - SCCB unaligned
>   - SCCB overlaps prefix or lowcore
>   - SCCB address higher than 2GB
> * Return codes for
>   - Invalid command
>   - SCCB too short (but at least 8)
>   - SCCB page boundary violation
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>  s390x/Makefile      |   1 +
>  s390x/sclp.c        | 465 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  s390x/unittests.cfg |   3 +
>  3 files changed, 469 insertions(+)
>  create mode 100644 s390x/sclp.c
[...]
> +/**
> + * Test SCCB page boundary violations.
> + */
> +static void test_boundary(void)
> +{
> +	const uint32_t cmd = SCLP_CMD_WRITE_EVENT_DATA;
> +	const uint16_t res = SCLP_RC_SCCB_BOUNDARY_VIOLATION;
> +	WriteEventData *sccb = (WriteEventData *)sccb_template;
> +	int len, offset;
> +
> +	memset(sccb_template, 0, sizeof(sccb_template));
> +	sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
> +	for (len = 32; len <= 4096; len++) {
> +		offset = len & 7 ? len & ~7 : len - 8;

I needed some time to understand that line. I think it would be easier
that way:

		offset = (len - 1) & ~7;

?

Anyway, no need to respin just because of that line ... the rest of the
patch looks ok to me.

> diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
> index f1b07cd..75e3d37 100644
> --- a/s390x/unittests.cfg
> +++ b/s390x/unittests.cfg
> @@ -75,3 +75,6 @@ file = stsi.elf
>  [smp]
>  file = smp.elf
>  extra_params =-smp 2
> +
> +[sclp]
> +file = sclp.elf

It's a little bit sad that some of the tests require < 2G of RAM while
other tests should (also) be done with > 2G if I understood that
correctly. So currently not all tests can be run automatically but just
starting the "run_tests.sh" script, right?

It does not have to be right now (i.e. could also be a follow-up patch
later), but what about adding two sections to the unittests.cfg file,
one with less and one with more than 2G of RAM? E.g.:

[sclp-1g]
file = sclp.elf
extra_params = -m 1G

[sclp-3g]
file = sclp.elf
extra_params = -m 3G -append "somemagicparametertoonlyrunthebigmemtest"

?

 Thomas

Re: [kvm-unit-tests PATCH v4 3/3] s390x: SCLP unit test

[Janosch Frank]

[-- Attachment #1.1: Type: text/plain, Size: 17283 bytes --]

On 11/19/19 10:53 AM, Claudio Imbrenda wrote:
> SCLP unit test. Testing the following:
> 
> * Correctly ignoring instruction bits that should be ignored
> * Privileged instruction check
> * Check for addressing exceptions
> * Specification exceptions:
>   - SCCB size less than 8
>   - SCCB unaligned
>   - SCCB overlaps prefix or lowcore
>   - SCCB address higher than 2GB
> * Return codes for
>   - Invalid command
>   - SCCB too short (but at least 8)
>   - SCCB page boundary violation
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>  s390x/Makefile      |   1 +
>  s390x/sclp.c        | 465 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  s390x/unittests.cfg |   3 +
>  3 files changed, 469 insertions(+)
>  create mode 100644 s390x/sclp.c
> 
> diff --git a/s390x/Makefile b/s390x/Makefile
> index 3744372..ddb4b48 100644
> --- a/s390x/Makefile
> +++ b/s390x/Makefile
> @@ -16,6 +16,7 @@ tests += $(TEST_DIR)/diag288.elf
>  tests += $(TEST_DIR)/stsi.elf
>  tests += $(TEST_DIR)/skrf.elf
>  tests += $(TEST_DIR)/smp.elf
> +tests += $(TEST_DIR)/sclp.elf
>  tests_binary = $(patsubst %.elf,%.bin,$(tests))
>  
>  all: directories test_cases test_cases_binary
> diff --git a/s390x/sclp.c b/s390x/sclp.c
> new file mode 100644
> index 0000000..aeb0b04
> --- /dev/null
> +++ b/s390x/sclp.c
> @@ -0,0 +1,465 @@
> +/*
> + * Service Call tests
> + *
> + * Copyright (c) 2019 IBM Corp
> + *
> + * Authors:
> + *  Claudio Imbrenda <imbrenda@linux.ibm.com>
> + *
> + * This code is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2.
> + */
> +
> +#include <libcflat.h>
> +#include <asm/page.h>
> +#include <asm/asm-offsets.h>
> +#include <asm/interrupt.h>
> +#include <sclp.h>
> +
> +#define PGM_NONE	1
> +#define PGM_BIT_SPEC	(1ULL << PGM_INT_CODE_SPECIFICATION)
> +#define PGM_BIT_ADDR	(1ULL << PGM_INT_CODE_ADDRESSING)
> +#define PGM_BIT_PRIV	(1ULL << PGM_INT_CODE_PRIVILEGED_OPERATION)
> +#define MKPTR(x) ((void *)(uint64_t)(x))
> +
> +/* two pages of scratch memory to be used for some of the tests */
> +static uint8_t pagebuf[PAGE_SIZE * 2] __attribute__((aligned(PAGE_SIZE * 2)));
> +/* used as prefix when testing prefix access, to guarantee that prefix != 0 */
> +static uint8_t prefix_buf[PAGE_SIZE * 2] __attribute__((aligned(PAGE_SIZE * 2)));

"to guarantee that prefix != 0" ... also returns in an error when used
as a sccb address?


> +/* SCCB template used to */

Used to what? :-)

> +static uint8_t sccb_template[PAGE_SIZE];

> +/* the valid command code to use for getting SCP information */

/* The sccb command code we'll use for the "read info" command. */

> +static uint32_t valid_code;

That's an unfortunate name for this variable.
How about: read_info_cmd_code?


> +/* points to lowcore (real address 0) */
> +static struct lowcore *lc;

I'd guess that a comment for this variable is a bit pointless.


I find this hard to read with all the comments above.

> +
> +/**
> + * Perform one service call, handling exceptions and interrupts.
> + */
> +static int sclp_service_call_test(unsigned int command, void *sccb)
> +{
> +	int cc;
> +
> +	sclp_mark_busy();
> +	sclp_setup_int();
> +	cc = servc(command, __pa(sccb));
> +	if (lc->pgm_int_code) {
> +		sclp_handle_ext();
> +		return 0;
> +	}
> +	if (!cc)
> +		sclp_wait_busy();
> +	return cc;
> +}
> +
> +/**
> + * Perform one test at the given address, optionally using the SCCB template,
> + * checking for the expected program interrupts and return codes.
> + *
> + * The parameter buf_len indicates the number of bytes of the template that
> + * should be copied to the test address, and should be 0 when the test
> + * address is invalid, in which case nothing is copied.
> + *
> + * The template is used to simplify tests where the same buffer content is
> + * used many times in a row, at different addresses.
> + *
> + * Returns true in case of success or false in case of failure
> + */
> +static bool test_one_sccb(uint32_t cmd, uint8_t *addr, uint16_t buf_len, uint64_t exp_pgm, uint16_t exp_rc)
> +{
> +	SCCBHeader *h = (SCCBHeader *)addr;
> +	int res, pgm;
> +
> +	/* Copy the template to the test address if needed */
> +	if (buf_len)
> +		memcpy(addr, sccb_template, buf_len);
> +	expect_pgm_int();
> +	/* perform the actuall call */

s/actuall/actual/

> +	res = sclp_service_call_test(cmd, h);
> +	if (res) {
> +		report_info("SCLP not ready (command %#x, address %p, cc %d)", cmd, addr, res);
> +		return false;
> +	}
> +	pgm = clear_pgm_int();
> +	/* Check if the program exception was one of the expected ones */
> +	if (!((1ULL << pgm) & exp_pgm)) {
> +		report_info("First failure at addr %p, buf_len %d, cmd %#x, pgm code %d",
> +				addr, buf_len, cmd, pgm);
> +		return false;
> +	}
> +	/* Check if the response code is the one expected */
> +	if (exp_rc && exp_rc != h->response_code) {
> +		report_info("First failure at addr %p, buf_len %d, cmd %#x, resp code %#x",
> +				addr, buf_len, cmd, h->response_code);
> +		return false;
> +	}
> +	return true;
> +}
> +
> +/**
> + * Wrapper for test_one_sccb to set up a simple SCCB template.
> + *
> + * The parameter sccb_len indicates the value that will be saved in the SCCB
> + * length field of the SCCB, buf_len indicates the number of bytes of
> + * template that need to be copied to the actual test address. In many cases
> + * it's enough to clear/copy the first 8 bytes of the buffer, while the SCCB
> + * itself can be larger.
> + *
> + * Returns true in case of success or false in case of failure
> + */
> +static bool test_one_simple(uint32_t cmd, uint8_t *addr, uint16_t sccb_len,
> +			uint16_t buf_len, uint64_t exp_pgm, uint16_t exp_rc)
> +{
> +	memset(sccb_template, 0, sizeof(sccb_template));
> +	((SCCBHeader *)sccb_template)->length = sccb_len;
> +	return test_one_sccb(cmd, addr, buf_len, exp_pgm, exp_rc);
> +}
> +
> +/**
> + * Test SCCB lengths < 8.
> + */
> +static void test_sccb_too_short(void)
> +{
> +	int len;
> +
> +	for (len = 0; len < 8; len++)
> +		if (!test_one_simple(valid_code, pagebuf, len, 8, PGM_BIT_SPEC, 0))
> +			break;
> +
> +	report("SCCB too short", len == 8);
> +}
> +
> +/**
> + * Test SCCBs that are not 64-bit aligned.
> + */
> +static void test_sccb_unaligned(void)
> +{
> +	int offset;
> +
> +	for (offset = 1; offset < 8; offset++)
> +		if (!test_one_simple(valid_code, offset + pagebuf, 8, 8, PGM_BIT_SPEC, 0))
> +			break;
> +	report("SCCB unaligned", offset == 8);
> +}
> +
> +/**
> + * Test SCCBs whose address is in the lowcore or prefix area.
> + */
> +static void test_sccb_prefix(void)
> +{
> +	uint8_t scratch[2 * PAGE_SIZE];
> +	uint32_t prefix, new_prefix;
> +	int offset;
> +
> +	/*
> +	 * copy the current lowcore to the future new location, otherwise we
> +	 * will not have a valid lowcore after setting the new prefix.
> +	 */
> +	memcpy(prefix_buf, 0, 2 * PAGE_SIZE);
> +	/* save the current prefix (it's probably going to be 0) */
> +	asm volatile("stpx %0" : "=Q" (prefix));

s390x/intercept.c already uses it, maybe we can move it to the library
along with spx?

> +	/*
> +	 * save the current content of absolute pages 0 and 1, so we can
> +	 * restore them after we trash them later on
> +	 */
> +	memcpy(scratch, (void *)(intptr_t)prefix, 2 * PAGE_SIZE);
> +	/* set the new prefix to prefix_buf */
> +	new_prefix = (uint32_t)(intptr_t)prefix_buf;
> +	asm volatile("spx %0" : : "Q" (new_prefix) : "memory");
> +
> +	/*
> +	 * testing with SCCB addresses in the lowcore; since we can't
> +	 * actually trash the lowcore (unsurprisingly, things break if we
> +	 * do), this will be a read-only test.
> +	 */
> +	for (offset = 0; offset < 2 * PAGE_SIZE; offset += 8)
> +		if (!test_one_sccb(valid_code, MKPTR(offset), 0, PGM_BIT_SPEC, 0))
> +			break;
> +	report("SCCB low pages", offset == 2 * PAGE_SIZE);
> +
> +	/*
> +	 * this will trash the contents of the two pages at absolute
> +	 * address 0; we will need to restore them later.
> +	 */
> +	for (offset = 0; offset < 2 * PAGE_SIZE; offset += 8)
> +		if (!test_one_simple(valid_code, MKPTR(new_prefix + offset), 8, 8, PGM_BIT_SPEC, 0))
> +			break;
> +	report("SCCB prefix pages", offset == 2 * PAGE_SIZE);
> +
> +	/* restore the previous contents of absolute pages 0 and 1 */
> +	memcpy(prefix_buf, 0, 2 * PAGE_SIZE);
> +	/* restore the prefix to the original value */
> +	asm volatile("spx %0" : : "Q" (prefix) : "memory");
> +}
> +
> +/**
> + * Test SCCBs that are above 2GB. If outside of memory, an addressing
> + * exception is also allowed.
> + */
> +static void test_sccb_high(void)
> +{
> +	SCCBHeader *h = (SCCBHeader *)pagebuf;
> +	uintptr_t a[33 * 4 * 2 + 2];	/* for the list of addresses to test */
> +
> +	uint64_t maxram;
> +	int i, pgm, len = 0;
> +
> +	h->length = 8;
> +	/* addresses with 1 bit set in the first 33 bits */
> +	for (i = 0; i < 33; i++)
> +		a[len++] = 1UL << (i + 31);
> +	/* addresses with 2 consecutive bits set in the first 33 bits */
> +	for (i = 0; i < 33; i++)
> +		a[len++] = 3UL << (i + 31);
> +	/* addresses with all bits set in bits 0..N */
> +	for (i = 0; i < 33; i++)
> +		a[len++] = 0xffffffff80000000UL << i;
> +	/* addresses with all bits set in bits N..33 */
> +	a[len++] = 0x80000000;
> +	for (i = 1; i < 33; i++, len++)
> +		a[len] = a[len - 1] | (1UL << (i + 31));
> +	/* all the addresses above, but adding the offset of a valid buffer */
> +	for (i = 0; i < len; i++)
> +		a[len + i] = a[i] + (intptr_t)h;
> +	len += i;
> +	/* two more hand-crafted addresses */
> +	a[len++] = 0xdeadbeef00000000;
> +	a[len++] = 0xdeaddeadbeef0000;
> +
> +	maxram = get_ram_size();
> +	for (i = 0; i < len; i++) {
> +		pgm = PGM_BIT_SPEC | (a[i] >= maxram ? PGM_BIT_ADDR : 0);
> +		if (!test_one_sccb(valid_code, (void *)a[i], 0, pgm, 0))
> +			break;
> +	}
> +	report("SCCB high addresses", i == len);
> +}
> +
> +/**
> + * Test invalid commands, both invalid command detail codes and valid
> + * ones with invalid command class code.
> + */
> +static void test_inval(void)
> +{
> +	const uint16_t res = SCLP_RC_INVALID_SCLP_COMMAND;
> +	uint32_t cmd;
> +	int i;
> +
> +	report_prefix_push("Invalid command");
> +	for (i = 0; i < 65536; i++) {
> +		cmd = 0xdead0000 | i;
> +		if (!test_one_simple(cmd, pagebuf, PAGE_SIZE, PAGE_SIZE, PGM_NONE, res))
> +			break;
> +	}
> +	report("Command detail code", i == 65536);
> +
> +	for (i = 0; i < 256; i++) {
> +		cmd = (valid_code & ~0xff) | i;
> +		if (cmd == valid_code)
> +			continue;
> +		if (!test_one_simple(cmd, pagebuf, PAGE_SIZE, PAGE_SIZE, PGM_NONE, res))
> +			break;
> +	}
> +	report("Command class code", i == 256);
> +	report_prefix_pop();
> +}
> +
> +
> +/**
> + * Test short SCCBs (but larger than 8).
> + */
> +static void test_short(void)
> +{
> +	const uint16_t res = SCLP_RC_INSUFFICIENT_SCCB_LENGTH;
> +	int len;
> +
> +	for (len = 8; len < 144; len++)
> +		if (!test_one_simple(valid_code, pagebuf, len, len, PGM_NONE, res))
> +			break;
> +	report("Insufficient SCCB length (Read SCP info)", len == 144);
> +
> +	for (len = 8; len < 40; len++)
> +		if (!test_one_simple(SCLP_READ_CPU_INFO, pagebuf, len, len, PGM_NONE, res))
> +			break;
> +	report("Insufficient SCCB length (Read CPU info)", len == 40);
> +}
> +
> +/**
> + * Test SCCB page boundary violations.
> + */
> +static void test_boundary(void)
> +{
> +	const uint32_t cmd = SCLP_CMD_WRITE_EVENT_DATA;
> +	const uint16_t res = SCLP_RC_SCCB_BOUNDARY_VIOLATION;
> +	WriteEventData *sccb = (WriteEventData *)sccb_template;
> +	int len, offset;
> +
> +	memset(sccb_template, 0, sizeof(sccb_template));
> +	sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
> +	for (len = 32; len <= 4096; len++) {
> +		offset = len & 7 ? len & ~7 : len - 8;
> +		for (offset = 4096 - offset; offset < 4096; offset += 8) {
> +			sccb->h.length = len;
> +			if (!test_one_sccb(cmd, offset + pagebuf, len, PGM_NONE, res))
> +				goto out;
> +		}
> +	}
> +out:
> +	report("SCCB page boundary violation", len > 4096 && offset == 4096);
> +}
> +
> +/**
> + * Test excessively long SCCBs.
> + */
> +static void test_toolong(void)
> +{
> +	const uint32_t cmd = SCLP_CMD_WRITE_EVENT_DATA;
> +	const uint16_t res = SCLP_RC_SCCB_BOUNDARY_VIOLATION;
> +	WriteEventData *sccb = (WriteEventData *)sccb_template;
> +	int len;
> +
> +	memset(sccb_template, 0, sizeof(sccb_template));
> +	sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
> +	for (len = 4097; len < 8192; len++) {
> +		sccb->h.length = len;
> +		if (!test_one_sccb(cmd, pagebuf, PAGE_SIZE, PGM_NONE, res))
> +			break;
> +	}
> +	report("SCCB bigger than 4k", len == 8192);
> +}
> +
> +/**
> + * Test privileged operation.
> + */
> +static void test_priv(void)
> +{
> +	SCCBHeader *h = (SCCBHeader *)pagebuf;
> +
> +	report_prefix_push("Privileged operation");
> +	h->length = 8;
> +	expect_pgm_int();
> +	enter_pstate();
> +	servc(valid_code, __pa(h));
> +	check_pgm_int_code(PGM_INT_CODE_PRIVILEGED_OPERATION);
> +	report_prefix_pop();
> +}
> +
> +/**
> + * Test addressing exceptions. We need to test SCCB addresses between the
> + * end of available memory and 2GB, because after 2GB a specification
> + * exception is also allowed.
> + * Only applicable if the VM has less than 2GB of memory
> + */
> +static void test_addressing(void)
> +{
> +	unsigned long i, maxram = get_ram_size();
> +
> +	/* the VM has more than 2GB of memory */
> +	if (maxram >= 0x80000000) {
> +		report_skip("Invalid SCCB address");
> +		return;
> +	}
> +	/* test all possible valid addresses immediately after the end of memory
> +	 * up to 64KB after the end of memory
> +	 */
> +	for (i = 0; i < 0x10000 && i + maxram < 0x80000000; i += 8)
> +		if (!test_one_sccb(valid_code, MKPTR(i + maxram), 0, PGM_BIT_ADDR, 0))
> +			goto out;
> +	/* test more addresses until we reach 1MB after end of memory;
> +	 * increment by a prime number (times 8) in order to test all
> +	 * possible valid offsets inside pages
> +	 */
> +	for (; i < 0x100000 && i + maxram < 0x80000000 ; i += 808)
> +		if (!test_one_sccb(valid_code, MKPTR(i + maxram), 0, PGM_BIT_ADDR, 0))
> +			goto out;
> +	/* test the remaining addresses until we reach address 2GB;
> +	 * increment by a prime number (times 8) in order to test all
> +	 * possible valid offsets inside pages
> +	 */
> +	for (; i < 0x80000000; i += 800024)
> +		if (!test_one_sccb(valid_code, MKPTR(i + maxram), 0, PGM_BIT_ADDR, 0))
> +			goto out;
> +out:
> +	report("Invalid SCCB address", i >= 0x80000000);
> +}
> +
> +/**
> + * Test some bits in the instruction format that are specified to be ignored.
> + */
> +static void test_instbits(void)
> +{
> +	SCCBHeader *h = (SCCBHeader *)pagebuf;
> +	int cc;
> +
> +	expect_pgm_int();
> +	sclp_mark_busy();
> +	h->length = 8;
> +	sclp_setup_int();
> +
> +	asm volatile(
> +		"       .insn   rre,0xb2204200,%1,%2\n"  /* servc %1,%2 */
> +		"       ipm     %0\n"
> +		"       srl     %0,28"
> +		: "=&d" (cc) : "d" (valid_code), "a" (__pa(pagebuf))
> +		: "cc", "memory");
> +	if (lc->pgm_int_code) {
> +		sclp_handle_ext();
> +		cc = 1;
> +	} else if (!cc)
> +		sclp_wait_busy();
> +	report("Instruction format ignored bits", cc == 0);
> +}
> +
> +/**
> + * Find a valid SCLP command code; not all codes are always allowed, and
> + * probing should be performed in the right order.

Find valid READ INFO command code

> + */
> +static void find_valid_sclp_code(void)
> +{
> +	const unsigned int commands[] = { SCLP_CMDW_READ_SCP_INFO_FORCED,
> +					  SCLP_CMDW_READ_SCP_INFO };
> +	SCCBHeader *h = (SCCBHeader *)pagebuf;
> +	int i, cc;
> +
> +	for (i = 0; i < ARRAY_SIZE(commands); i++) {
> +		sclp_mark_busy();
> +		memset(h, 0, sizeof(*h));
> +		h->length = 4096;
> +
> +		valid_code = commands[i];
> +		cc = sclp_service_call(commands[i], h);
> +		if (cc)
> +			break;
> +		if (h->response_code == SCLP_RC_NORMAL_READ_COMPLETION)
> +			return;
> +		if (h->response_code != SCLP_RC_INVALID_SCLP_COMMAND)
> +			break;
> +	}
> +	valid_code = 0;
> +	report_abort("READ_SCP_INFO failed");
> +}
> +
> +int main(void)
> +{
> +	report_prefix_push("sclp");
> +	find_valid_sclp_code();
> +
> +	/* Test some basic things */
> +	test_instbits();
> +	test_priv();
> +	test_addressing();
> +
> +	/* Test the specification exceptions */
> +	test_sccb_too_short();
> +	test_sccb_unaligned();
> +	test_sccb_prefix();
> +	test_sccb_high();
> +
> +	/* Test the expected response codes */
> +	test_inval();
> +	test_short();
> +	test_boundary();
> +	test_toolong();
> +
> +	return report_summary();
> +}
> diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
> index f1b07cd..75e3d37 100644
> --- a/s390x/unittests.cfg
> +++ b/s390x/unittests.cfg
> @@ -75,3 +75,6 @@ file = stsi.elf
>  [smp]
>  file = smp.elf
>  extra_params =-smp 2
> +
> +[sclp]
> +file = sclp.elf

I like Tomas' idea about the two tests.



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