From: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx>
Tests no-execute (Instruction Execution Protection) DAT protection.
Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
---
This was originally part of my first patchset, but was pushed back
after David introduced virtual memory allocation. It's more a RFC, as
I'm not completely happy with the memory management manipulation I do.
---
lib/s390x/asm/interrupt.h | 1 +
lib/s390x/interrupt.c | 9 +++++
s390x/Makefile | 1 +
s390x/iep.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++
s390x/unittests.cfg | 4 +++
5 files changed, 104 insertions(+)
create mode 100644 s390x/iep.c
diff --git a/lib/s390x/asm/interrupt.h b/lib/s390x/asm/interrupt.h
index 3ccc8e3..39ae534 100644
--- a/lib/s390x/asm/interrupt.h
+++ b/lib/s390x/asm/interrupt.h
@@ -15,6 +15,7 @@ void handle_pgm_int(void);
void expect_pgm_int(void);
uint16_t clear_pgm_int(void);
void check_pgm_int_code(uint16_t code);
+void register_pgm_handler(void (*handler)(struct lowcore *));
/* Activate low-address protection */
static inline void low_prot_enable(void)
diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
index 56c7603..fe6cdba 100644
--- a/lib/s390x/interrupt.c
+++ b/lib/s390x/interrupt.c
@@ -15,6 +15,7 @@
static bool pgm_int_expected;
static struct lowcore *lc;
+static void (*custom_pgm_handler)(struct lowcore *);
void expect_pgm_int(void)
{
@@ -41,8 +42,16 @@ void check_pgm_int_code(uint16_t code)
code == lc->pgm_int_code, code, lc->pgm_int_code);
}
+void register_pgm_handler(void (*handler)(struct lowcore *))
+{
+ custom_pgm_handler = handler;
+}
+
static void fixup_pgm_int(void)
{
+ if (custom_pgm_handler)
+ return custom_pgm_handler(lc);
+
switch (lc->pgm_int_code) {
case PGM_INT_CODE_PRIVILEGED_OPERATION:
/* Normal operation is in supervisor state, so this exception
diff --git a/s390x/Makefile b/s390x/Makefile
index abc3242..d4275a1 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -9,6 +9,7 @@ tests += $(TEST_DIR)/pfmf.elf
tests += $(TEST_DIR)/cmm.elf
tests += $(TEST_DIR)/vector.elf
tests += $(TEST_DIR)/gs.elf
+tests += $(TEST_DIR)/iep.elf
all: directories test_cases
diff --git a/s390x/iep.c b/s390x/iep.c
new file mode 100644
index 0000000..87f3007
--- /dev/null
+++ b/s390x/iep.c
@@ -0,0 +1,89 @@
+/*
+ * Instruction Execution Prevention (IEP) DAT test.
+ *
+ * Copyright (c) 2018 IBM Corp
+ *
+ * Authors:
+ * Janosch Frank <frankja@xxxxxxxxxxxxx>
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Library General Public License version 2.
+ */
+#include <libcflat.h>
+#include <vmalloc.h>
+#include <asm/facility.h>
+#include <asm/interrupt.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm-generic/barrier.h>
+
+static pteval_t *get_pte(pgd_t *pgtable, uintptr_t vaddr)
+{
+ pgd_t *pgd = pgd_offset(pgtable, vaddr);
+ p4d_t *p4d = p4d_offset(pgd, vaddr);
+ pud_t *pud = pud_offset(p4d, vaddr);
+ pmd_t *pmd = pmd_offset(pud, vaddr);
+ pte_t *pte = pte_offset(pmd, vaddr);
+
+ return &pte_val(*pte);
+}
+
+void iep_handler(struct lowcore *lc)
+{
+ if (lc->pgm_int_code == PGM_INT_CODE_PROTECTION)
+ lc->pgm_old_psw.addr = lc->sw_int_grs[14];
+}
+
+static void test_iep(void)
+{
+ uint16_t *code;
+ uint8_t *iepbuf = 0;
+ void (*fn)(void);
+ pteval_t *pte;
+ pgd_t *pgtable = (pgd_t *)(stctg(1) & ~(ASCE_DT_REGION1 | REGION_TABLE_LENGTH));
+
+
+ /* Enable IEP */
+ ctl_set_bit(0, 20);
+
+ /* Get and protect a page with the IEP bit */
+ iepbuf = alloc_page();
+ pte = get_pte(pgtable, (uintptr_t)iepbuf);
+ ipte((uintptr_t)iepbuf, pte);
+ *pte |= PAGE_ENTRY_IEP;
+ *pte &= ~PAGE_ENTRY_I;
+ mb();
+
+ register_pgm_handler(&iep_handler);
+
+ /* Code branches into r14 which contains the return address. */
+ code = (uint16_t *)iepbuf;
+ *code = 0x07fe;
+ asm volatile("" : : "m" (code));
+ fn = (void *)code;
+ mb();
+
+ expect_pgm_int();
+ /* Jump into protected page */
+ fn();
+ check_pgm_int_code(PGM_INT_CODE_PROTECTION);
+ ctl_clear_bit(0, 20);
+}
+
+int main(void)
+{
+ bool has_iep = test_facility(130);
+
+ report_prefix_push("iep");
+ report_xfail("DAT IEP available", !has_iep, has_iep);
+ if (!has_iep)
+ goto done;
+
+ /* Setup DAT 1:1 mapping and memory management */
+ setup_vm();
+ test_iep();
+
+done:
+ report_prefix_pop();
+ return report_summary();
+}
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index ff7eea1..760402e 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -55,3 +55,7 @@ file = vector.elf
[gs]
file = gs.elf
+
+[iep]
+file = iep.elf
+
--
2.7.4
