[patch 02/52] [PATCH] Improve address space mode selection.

Martin Schwidefsky
2009-11-13T15:17:26Z

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From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Introduce user_mode to replace the two variables switch_amode and
s390_noexec. There are three valid combinations of the old values:
1) switch_amode == 0 && s390_noexec == 0
2) switch_amode == 1 && s390_noexec == 0
3) switch_amode == 1 && s390_noexec == 1
They get replaced by
1) user_mode == HOME_SPACE_MODE
2) user_mode == PRIMARY_SPACE_MODE
3) user_mode == SECONDARY_SPACE_MODE
The new kernel parameter user_mode=[primary,secondary,home] lets
you choose the address space mode the user space processes should
use. In addition the CONFIG_S390_SWITCH_AMODE config option
is removed.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

arch/s390/Kconfig | 15 ---------------
arch/s390/defconfig | 1 -
arch/s390/include/asm/mmu_context.h | 4 ++--
arch/s390/include/asm/pgalloc.h | 3 ++-
arch/s390/include/asm/setup.h | 17 ++++++-----------
arch/s390/kernel/setup.c | 36 ++++++++++++++++++++----------------
arch/s390/kernel/vdso.c | 9 +++++----
arch/s390/kvm/Kconfig | 1 -
arch/s390/lib/uaccess_mvcos.c | 4 ----
arch/s390/mm/fault.c | 4 ++--
arch/s390/mm/pgtable.c | 2 +-
11 files changed, 38 insertions(+), 58 deletions(-)

Index: quilt-2.6/arch/s390/defconfig
===================================================================
--- quilt-2.6.orig/arch/s390/defconfig 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/defconfig 2009-11-13 16:08:12.000000000 +0100
@@ -185,7 +185,6 @@
CONFIG_COMPAT=y
CONFIG_SYSVIPC_COMPAT=y
CONFIG_AUDIT_ARCH=y
-CONFIG_S390_SWITCH_AMODE=y
CONFIG_S390_EXEC_PROTECT=y

#
Index: quilt-2.6/arch/s390/include/asm/mmu_context.h
===================================================================
--- quilt-2.6.orig/arch/s390/include/asm/mmu_context.h 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/include/asm/mmu_context.h 2009-11-13 16:08:12.000000000 +0100
@@ -36,7 +36,7 @@
mm->context.has_pgste = 1;
mm->context.alloc_pgste = 1;
} else {
- mm->context.noexec = s390_noexec;
+ mm->context.noexec = (user_mode == SECONDARY_SPACE_MODE);
mm->context.has_pgste = 0;
mm->context.alloc_pgste = 0;
}
@@ -58,7 +58,7 @@
pgd_t *pgd = mm->pgd;

S390_lowcore.user_asce = mm->context.asce_bits | __pa(pgd);
- if (switch_amode) {
+ if (user_mode != HOME_SPACE_MODE) {
/* Load primary space page table origin. */
pgd = mm->context.noexec ? get_shadow_table(pgd) : pgd;
S390_lowcore.user_exec_asce = mm->context.asce_bits | __pa(pgd);
Index: quilt-2.6/arch/s390/include/asm/pgalloc.h
===================================================================
--- quilt-2.6.orig/arch/s390/include/asm/pgalloc.h 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/include/asm/pgalloc.h 2009-11-13 16:08:12.000000000 +0100
@@ -143,7 +143,8 @@
spin_lock_init(&mm->context.list_lock);
INIT_LIST_HEAD(&mm->context.crst_list);
INIT_LIST_HEAD(&mm->context.pgtable_list);
- return (pgd_t *) crst_table_alloc(mm, s390_noexec);
+ return (pgd_t *)
+ crst_table_alloc(mm, user_mode == SECONDARY_SPACE_MODE);
}
#define pgd_free(mm, pgd) crst_table_free(mm, (unsigned long *) pgd)

Index: quilt-2.6/arch/s390/include/asm/setup.h
===================================================================
--- quilt-2.6.orig/arch/s390/include/asm/setup.h 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/include/asm/setup.h 2009-11-13 16:08:12.000000000 +0100
@@ -49,17 +49,12 @@

void detect_memory_layout(struct mem_chunk chunk[]);

-#ifdef CONFIG_S390_SWITCH_AMODE
-extern unsigned int switch_amode;
-#else
-#define switch_amode (0)
-#endif
-
-#ifdef CONFIG_S390_EXEC_PROTECT
-extern unsigned int s390_noexec;
-#else
-#define s390_noexec (0)
-#endif
+#define PRIMARY_SPACE_MODE 0
+#define ACCESS_REGISTER_MODE 1
+#define SECONDARY_SPACE_MODE 2
+#define HOME_SPACE_MODE 3
+
+extern unsigned int user_mode;

/*
* Machine features detected in head.S
Index: quilt-2.6/arch/s390/Kconfig
===================================================================
--- quilt-2.6.orig/arch/s390/Kconfig 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/Kconfig 2009-11-13 16:08:12.000000000 +0100
@@ -192,23 +192,8 @@
bool
default y

-config S390_SWITCH_AMODE
- bool "Switch kernel/user addressing modes"
- help
- This option allows to switch the addressing modes of kernel and user
- space. The kernel parameter switch_amode=on will enable this feature,
- default is disabled. Enabling this (via kernel parameter) on machines
- earlier than IBM System z9-109 EC/BC will reduce system performance.
-
- Note that this option will also be selected by selecting the execute
- protection option below. Enabling the execute protection via the
- noexec kernel parameter will also switch the addressing modes,
- independent of the switch_amode kernel parameter.
-
-
config S390_EXEC_PROTECT
bool "Data execute protection"
- select S390_SWITCH_AMODE
help
This option allows to enable a buffer overflow protection for user
space programs and it also selects the addressing mode option above.
Index: quilt-2.6/arch/s390/kernel/setup.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/setup.c 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/kernel/setup.c 2009-11-13 16:08:12.000000000 +0100
@@ -305,9 +305,8 @@
}
early_param("mem", early_parse_mem);

-#ifdef CONFIG_S390_SWITCH_AMODE
-unsigned int switch_amode = 0;
-EXPORT_SYMBOL_GPL(switch_amode);
+unsigned int user_mode = HOME_SPACE_MODE;
+EXPORT_SYMBOL_GPL(user_mode);

static int set_amode_and_uaccess(unsigned long user_amode,
unsigned long user32_amode)
@@ -340,23 +339,29 @@
*/
static int __init early_parse_switch_amode(char *p)
{
- switch_amode = 1;
+ if (user_mode != SECONDARY_SPACE_MODE)
+ user_mode = PRIMARY_SPACE_MODE;
return 0;
}
early_param("switch_amode", early_parse_switch_amode);

-#else /* CONFIG_S390_SWITCH_AMODE */
-static inline int set_amode_and_uaccess(unsigned long user_amode,
- unsigned long user32_amode)
+static int __init early_parse_user_mode(char *p)
{
+ if (p && strcmp(p, "primary") == 0)
+ user_mode = PRIMARY_SPACE_MODE;
+#ifdef CONFIG_S390_EXEC_PROTECT
+ else if (p && strcmp(p, "secondary") == 0)
+ user_mode = SECONDARY_SPACE_MODE;
+#endif
+ else if (!p || strcmp(p, "home") == 0)
+ user_mode = HOME_SPACE_MODE;
+ else
+ return 1;
return 0;
}
-#endif /* CONFIG_S390_SWITCH_AMODE */
+early_param("user_mode", early_parse_user_mode);

#ifdef CONFIG_S390_EXEC_PROTECT
-unsigned int s390_noexec = 0;
-EXPORT_SYMBOL_GPL(s390_noexec);
-
/*
* Enable execute protection?
*/
@@ -364,8 +369,7 @@
{
if (!strncmp(p, "off", 3))
return 0;
- switch_amode = 1;
- s390_noexec = 1;
+ user_mode = SECONDARY_SPACE_MODE;
return 0;
}
early_param("noexec", early_parse_noexec);
@@ -373,7 +377,7 @@

static void setup_addressing_mode(void)
{
- if (s390_noexec) {
+ if (user_mode == SECONDARY_SPACE_MODE) {
if (set_amode_and_uaccess(PSW_ASC_SECONDARY,
PSW32_ASC_SECONDARY))
pr_info("Execute protection active, "
@@ -381,7 +385,7 @@
else
pr_info("Execute protection active, "
"mvcos not available\n");
- } else if (switch_amode) {
+ } else if (user_mode == PRIMARY_SPACE_MODE) {
if (set_amode_and_uaccess(PSW_ASC_PRIMARY, PSW32_ASC_PRIMARY))
pr_info("Address spaces switched, "
"mvcos available\n");
@@ -411,7 +415,7 @@
lc->restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
lc->restart_psw.addr =
PSW_ADDR_AMODE | (unsigned long) restart_int_handler;
- if (switch_amode)
+ if (user_mode != HOME_SPACE_MODE)
lc->restart_psw.mask |= PSW_ASC_HOME;
lc->external_new_psw.mask = psw_kernel_bits;
lc->external_new_psw.addr =
Index: quilt-2.6/arch/s390/kernel/vdso.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/vdso.c 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/kernel/vdso.c 2009-11-13 16:08:12.000000000 +0100
@@ -86,7 +86,8 @@
unsigned int facility_list;

facility_list = stfl();
- vd->ectg_available = switch_amode && (facility_list & 1);
+ vd->ectg_available =
+ user_mode != HOME_SPACE_MODE && (facility_list & 1);
}

#ifdef CONFIG_64BIT
@@ -114,7 +115,7 @@

lowcore->vdso_per_cpu_data = __LC_PASTE;

- if (!switch_amode || !vdso_enabled)
+ if (user_mode == HOME_SPACE_MODE || !vdso_enabled)
return 0;

segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
@@ -160,7 +161,7 @@
unsigned long segment_table, page_table, page_frame;
u32 *psal, *aste;

- if (!switch_amode || !vdso_enabled)
+ if (user_mode == HOME_SPACE_MODE || !vdso_enabled)
return;

psal = (u32 *)(addr_t) lowcore->paste[4];
@@ -184,7 +185,7 @@

static void vdso_init_cr5(void)
{
- if (switch_amode && vdso_enabled)
+ if (user_mode != HOME_SPACE_MODE && vdso_enabled)
on_each_cpu(__vdso_init_cr5, NULL, 1);
}
#endif /* CONFIG_64BIT */
Index: quilt-2.6/arch/s390/kvm/Kconfig
===================================================================
--- quilt-2.6.orig/arch/s390/kvm/Kconfig 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/kvm/Kconfig 2009-11-13 16:08:12.000000000 +0100
@@ -20,7 +20,6 @@
depends on HAVE_KVM && EXPERIMENTAL
select PREEMPT_NOTIFIERS
select ANON_INODES
- select S390_SWITCH_AMODE
---help---
Support hosting paravirtualized guest machines using the SIE
virtualization capability on the mainframe. This should work
Index: quilt-2.6/arch/s390/lib/uaccess_mvcos.c
===================================================================
--- quilt-2.6.orig/arch/s390/lib/uaccess_mvcos.c 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/lib/uaccess_mvcos.c 2009-11-13 16:08:12.000000000 +0100
@@ -162,7 +162,6 @@
return size;
}

-#ifdef CONFIG_S390_SWITCH_AMODE
static size_t strnlen_user_mvcos(size_t count, const char __user *src)
{
char buf[256];
@@ -200,7 +199,6 @@
} while ((len_str == len) && (done < count));
return done;
}
-#endif /* CONFIG_S390_SWITCH_AMODE */

struct uaccess_ops uaccess_mvcos = {
.copy_from_user = copy_from_user_mvcos_check,
@@ -215,7 +213,6 @@
.futex_atomic_cmpxchg = futex_atomic_cmpxchg_std,
};

-#ifdef CONFIG_S390_SWITCH_AMODE
struct uaccess_ops uaccess_mvcos_switch = {
.copy_from_user = copy_from_user_mvcos,
.copy_from_user_small = copy_from_user_mvcos,
@@ -228,4 +225,3 @@
.futex_atomic_op = futex_atomic_op_pt,
.futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
};
-#endif
Index: quilt-2.6/arch/s390/mm/fault.c
===================================================================
--- quilt-2.6.orig/arch/s390/mm/fault.c 2009-11-13 16:08:12.000000000 +0100
+++ quilt-2.6/arch/s390/mm/fault.c 2009-11-13 16:08:12.000000000 +0100
@@ -112,7 +112,7 @@
if (trans_exc_code == 2)
/* Access via secondary space, set_fs setting decides */
return current->thread.mm_segment.ar4;
- if (!switch_amode)
+ if (user_mode == HOME_SPACE_MODE)
/* User space if the access has been done via home space. */
return trans_exc_code == 3;
/*
@@ -168,7 +168,7 @@
* terminate things with extreme prejudice.
*/
address = trans_exc_code & __FAIL_ADDR_MASK;
- if (user_space_fault(trans_exc_code) == 0)
+ if (!user_space_fault(trans_exc_code))
printk(KERN_ALERT "Unable to handle kernel pointer dereference"
" at virtual kernel address %p\n", (void *)address);
else
Index: quilt-2.6/arch/s390/mm/pgtable.c
===================================================================
--- quilt-2.6.orig/arch/s390/mm/pgtable.c 2009-11-13 15:48:32.000000000 +0100
+++ quilt-2.6/arch/s390/mm/pgtable.c 2009-11-13 16:08:12.000000000 +0100
@@ -269,7 +269,7 @@
struct mm_struct *mm, *old_mm;

/* Do we have switched amode? If no, we cannot do sie */
- if (!switch_amode)
+ if (user_mode == HOME_SPACE_MODE)
return -EINVAL;

/* Do we have pgstes? if yes, we are done */