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-rw-r--r--arch/s390/mm/fault.c746
1 files changed, 245 insertions, 501 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index e173b6187ad5..c421dd44ffbe 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -3,17 +3,19 @@
* S390 version
* Copyright IBM Corp. 1999
* Author(s): Hartmut Penner (hp@de.ibm.com)
- * Ulrich Weigand (uweigand@de.ibm.com)
+ * Ulrich Weigand (uweigand@de.ibm.com)
*
* Derived from "arch/i386/mm/fault.c"
* Copyright (C) 1995 Linus Torvalds
*/
#include <linux/kernel_stat.h>
+#include <linux/mmu_context.h>
#include <linux/perf_event.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
+#include <linux/jump_label.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
@@ -34,36 +36,27 @@
#include <linux/kfence.h>
#include <asm/asm-extable.h>
#include <asm/asm-offsets.h>
+#include <asm/ptrace.h>
+#include <asm/fault.h>
#include <asm/diag.h>
#include <asm/gmap.h>
#include <asm/irq.h>
-#include <asm/mmu_context.h>
#include <asm/facility.h>
#include <asm/uv.h>
#include "../kernel/entry.h"
-#define __FAIL_ADDR_MASK -4096L
-#define __SUBCODE_MASK 0x0600
-#define __PF_RES_FIELD 0x8000000000000000ULL
-
-#define VM_FAULT_BADCONTEXT ((__force vm_fault_t) 0x010000)
-#define VM_FAULT_BADMAP ((__force vm_fault_t) 0x020000)
-#define VM_FAULT_BADACCESS ((__force vm_fault_t) 0x040000)
-#define VM_FAULT_SIGNAL ((__force vm_fault_t) 0x080000)
-#define VM_FAULT_PFAULT ((__force vm_fault_t) 0x100000)
-
enum fault_type {
KERNEL_FAULT,
USER_FAULT,
GMAP_FAULT,
};
-static unsigned long store_indication __read_mostly;
+static DEFINE_STATIC_KEY_FALSE(have_store_indication);
static int __init fault_init(void)
{
if (test_facility(75))
- store_indication = 0xc00;
+ static_branch_enable(&have_store_indication);
return 0;
}
early_initcall(fault_init);
@@ -73,82 +66,90 @@ early_initcall(fault_init);
*/
static enum fault_type get_fault_type(struct pt_regs *regs)
{
- unsigned long trans_exc_code;
+ union teid teid = { .val = regs->int_parm_long };
+ struct gmap *gmap;
- trans_exc_code = regs->int_parm_long & 3;
- if (likely(trans_exc_code == 0)) {
- /* primary space exception */
+ if (likely(teid.as == PSW_BITS_AS_PRIMARY)) {
if (user_mode(regs))
return USER_FAULT;
if (!IS_ENABLED(CONFIG_PGSTE))
return KERNEL_FAULT;
- if (test_pt_regs_flag(regs, PIF_GUEST_FAULT))
+ gmap = (struct gmap *)S390_lowcore.gmap;
+ if (regs->cr1 == gmap->asce)
return GMAP_FAULT;
return KERNEL_FAULT;
}
- if (trans_exc_code == 2)
+ if (teid.as == PSW_BITS_AS_SECONDARY)
return USER_FAULT;
- if (trans_exc_code == 1) {
- /* access register mode, not used in the kernel */
+ /* Access register mode, not used in the kernel */
+ if (teid.as == PSW_BITS_AS_ACCREG)
return USER_FAULT;
- }
- /* home space exception -> access via kernel ASCE */
+ /* Home space -> access via kernel ASCE */
return KERNEL_FAULT;
}
-static int bad_address(void *p)
+static unsigned long get_fault_address(struct pt_regs *regs)
{
- unsigned long dummy;
+ union teid teid = { .val = regs->int_parm_long };
- return get_kernel_nofault(dummy, (unsigned long *)p);
+ return teid.addr * PAGE_SIZE;
+}
+
+static __always_inline bool fault_is_write(struct pt_regs *regs)
+{
+ union teid teid = { .val = regs->int_parm_long };
+
+ if (static_branch_likely(&have_store_indication))
+ return teid.fsi == TEID_FSI_STORE;
+ return false;
}
static void dump_pagetable(unsigned long asce, unsigned long address)
{
- unsigned long *table = __va(asce & _ASCE_ORIGIN);
+ unsigned long entry, *table = __va(asce & _ASCE_ORIGIN);
pr_alert("AS:%016lx ", asce);
switch (asce & _ASCE_TYPE_MASK) {
case _ASCE_TYPE_REGION1:
table += (address & _REGION1_INDEX) >> _REGION1_SHIFT;
- if (bad_address(table))
+ if (get_kernel_nofault(entry, table))
goto bad;
- pr_cont("R1:%016lx ", *table);
- if (*table & _REGION_ENTRY_INVALID)
+ pr_cont("R1:%016lx ", entry);
+ if (entry & _REGION_ENTRY_INVALID)
goto out;
- table = __va(*table & _REGION_ENTRY_ORIGIN);
+ table = __va(entry & _REGION_ENTRY_ORIGIN);
fallthrough;
case _ASCE_TYPE_REGION2:
table += (address & _REGION2_INDEX) >> _REGION2_SHIFT;
- if (bad_address(table))
+ if (get_kernel_nofault(entry, table))
goto bad;
- pr_cont("R2:%016lx ", *table);
- if (*table & _REGION_ENTRY_INVALID)
+ pr_cont("R2:%016lx ", entry);
+ if (entry & _REGION_ENTRY_INVALID)
goto out;
- table = __va(*table & _REGION_ENTRY_ORIGIN);
+ table = __va(entry & _REGION_ENTRY_ORIGIN);
fallthrough;
case _ASCE_TYPE_REGION3:
table += (address & _REGION3_INDEX) >> _REGION3_SHIFT;
- if (bad_address(table))
+ if (get_kernel_nofault(entry, table))
goto bad;
- pr_cont("R3:%016lx ", *table);
- if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
+ pr_cont("R3:%016lx ", entry);
+ if (entry & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
goto out;
- table = __va(*table & _REGION_ENTRY_ORIGIN);
+ table = __va(entry & _REGION_ENTRY_ORIGIN);
fallthrough;
case _ASCE_TYPE_SEGMENT:
table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
- if (bad_address(table))
+ if (get_kernel_nofault(entry, table))
goto bad;
- pr_cont("S:%016lx ", *table);
- if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
+ pr_cont("S:%016lx ", entry);
+ if (entry & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
goto out;
- table = __va(*table & _SEGMENT_ENTRY_ORIGIN);
+ table = __va(entry & _SEGMENT_ENTRY_ORIGIN);
}
table += (address & _PAGE_INDEX) >> _PAGE_SHIFT;
- if (bad_address(table))
+ if (get_kernel_nofault(entry, table))
goto bad;
- pr_cont("P:%016lx ", *table);
+ pr_cont("P:%016lx ", entry);
out:
pr_cont("\n");
return;
@@ -158,163 +159,113 @@ bad:
static void dump_fault_info(struct pt_regs *regs)
{
+ union teid teid = { .val = regs->int_parm_long };
unsigned long asce;
pr_alert("Failing address: %016lx TEID: %016lx\n",
- regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
+ get_fault_address(regs), teid.val);
pr_alert("Fault in ");
- switch (regs->int_parm_long & 3) {
- case 3:
+ switch (teid.as) {
+ case PSW_BITS_AS_HOME:
pr_cont("home space ");
break;
- case 2:
+ case PSW_BITS_AS_SECONDARY:
pr_cont("secondary space ");
break;
- case 1:
+ case PSW_BITS_AS_ACCREG:
pr_cont("access register ");
break;
- case 0:
+ case PSW_BITS_AS_PRIMARY:
pr_cont("primary space ");
break;
}
pr_cont("mode while using ");
switch (get_fault_type(regs)) {
case USER_FAULT:
- asce = S390_lowcore.user_asce;
+ asce = S390_lowcore.user_asce.val;
pr_cont("user ");
break;
case GMAP_FAULT:
- asce = ((struct gmap *) S390_lowcore.gmap)->asce;
+ asce = ((struct gmap *)S390_lowcore.gmap)->asce;
pr_cont("gmap ");
break;
case KERNEL_FAULT:
- asce = S390_lowcore.kernel_asce;
+ asce = S390_lowcore.kernel_asce.val;
pr_cont("kernel ");
break;
default:
unreachable();
}
pr_cont("ASCE.\n");
- dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
+ dump_pagetable(asce, get_fault_address(regs));
}
int show_unhandled_signals = 1;
void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault)
{
+ static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
+
if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
return;
if (!unhandled_signal(current, signr))
return;
- if (!printk_ratelimit())
+ if (!__ratelimit(&rs))
return;
- printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ",
- regs->int_code & 0xffff, regs->int_code >> 17);
+ pr_alert("User process fault: interruption code %04x ilc:%d ",
+ regs->int_code & 0xffff, regs->int_code >> 17);
print_vma_addr(KERN_CONT "in ", regs->psw.addr);
- printk(KERN_CONT "\n");
+ pr_cont("\n");
if (is_mm_fault)
dump_fault_info(regs);
show_regs(regs);
}
-/*
- * Send SIGSEGV to task. This is an external routine
- * to keep the stack usage of do_page_fault small.
- */
-static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
+static void do_sigsegv(struct pt_regs *regs, int si_code)
{
report_user_fault(regs, SIGSEGV, 1);
- force_sig_fault(SIGSEGV, si_code,
- (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
+ force_sig_fault(SIGSEGV, si_code, (void __user *)get_fault_address(regs));
}
-static noinline void do_no_context(struct pt_regs *regs)
+static void handle_fault_error_nolock(struct pt_regs *regs, int si_code)
{
+ enum fault_type fault_type;
+ unsigned long address;
+ bool is_write;
+
+ if (user_mode(regs)) {
+ if (WARN_ON_ONCE(!si_code))
+ si_code = SEGV_MAPERR;
+ return do_sigsegv(regs, si_code);
+ }
if (fixup_exception(regs))
return;
- /*
- * Oops. The kernel tried to access some bad page. We'll have to
- * terminate things with extreme prejudice.
- */
- if (get_fault_type(regs) == KERNEL_FAULT)
- printk(KERN_ALERT "Unable to handle kernel pointer dereference"
- " in virtual kernel address space\n");
+ fault_type = get_fault_type(regs);
+ if (fault_type == KERNEL_FAULT) {
+ address = get_fault_address(regs);
+ is_write = fault_is_write(regs);
+ if (kfence_handle_page_fault(address, is_write, regs))
+ return;
+ }
+ if (fault_type == KERNEL_FAULT)
+ pr_alert("Unable to handle kernel pointer dereference in virtual kernel address space\n");
else
- printk(KERN_ALERT "Unable to handle kernel paging request"
- " in virtual user address space\n");
+ pr_alert("Unable to handle kernel paging request in virtual user address space\n");
dump_fault_info(regs);
die(regs, "Oops");
}
-static noinline void do_low_address(struct pt_regs *regs)
+static void handle_fault_error(struct pt_regs *regs, int si_code)
{
- /* Low-address protection hit in kernel mode means
- NULL pointer write access in kernel mode. */
- if (regs->psw.mask & PSW_MASK_PSTATE) {
- /* Low-address protection hit in user mode 'cannot happen'. */
- die (regs, "Low-address protection");
- }
+ struct mm_struct *mm = current->mm;
- do_no_context(regs);
-}
-
-static noinline void do_sigbus(struct pt_regs *regs)
-{
- /*
- * Send a sigbus, regardless of whether we were in kernel
- * or user mode.
- */
- force_sig_fault(SIGBUS, BUS_ADRERR,
- (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
+ mmap_read_unlock(mm);
+ handle_fault_error_nolock(regs, si_code);
}
-static noinline void do_fault_error(struct pt_regs *regs, int access,
- vm_fault_t fault)
+static void do_sigbus(struct pt_regs *regs)
{
- int si_code;
-
- switch (fault) {
- case VM_FAULT_BADACCESS:
- case VM_FAULT_BADMAP:
- /* Bad memory access. Check if it is kernel or user space. */
- if (user_mode(regs)) {
- /* User mode accesses just cause a SIGSEGV */
- si_code = (fault == VM_FAULT_BADMAP) ?
- SEGV_MAPERR : SEGV_ACCERR;
- do_sigsegv(regs, si_code);
- break;
- }
- fallthrough;
- case VM_FAULT_BADCONTEXT:
- case VM_FAULT_PFAULT:
- do_no_context(regs);
- break;
- case VM_FAULT_SIGNAL:
- if (!user_mode(regs))
- do_no_context(regs);
- break;
- default: /* fault & VM_FAULT_ERROR */
- if (fault & VM_FAULT_OOM) {
- if (!user_mode(regs))
- do_no_context(regs);
- else
- pagefault_out_of_memory();
- } else if (fault & VM_FAULT_SIGSEGV) {
- /* Kernel mode? Handle exceptions or die */
- if (!user_mode(regs))
- do_no_context(regs);
- else
- do_sigsegv(regs, SEGV_MAPERR);
- } else if (fault & VM_FAULT_SIGBUS) {
- /* Kernel mode? Handle exceptions or die */
- if (!user_mode(regs))
- do_no_context(regs);
- else
- do_sigbus(regs);
- } else
- BUG();
- break;
- }
+ force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)get_fault_address(regs));
}
/*
@@ -323,161 +274,178 @@ static noinline void do_fault_error(struct pt_regs *regs, int access,
* routines.
*
* interruption code (int_code):
- * 04 Protection -> Write-Protection (suppression)
- * 10 Segment translation -> Not present (nullification)
- * 11 Page translation -> Not present (nullification)
- * 3b Region third trans. -> Not present (nullification)
+ * 04 Protection -> Write-Protection (suppression)
+ * 10 Segment translation -> Not present (nullification)
+ * 11 Page translation -> Not present (nullification)
+ * 3b Region third trans. -> Not present (nullification)
*/
-static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
+static void do_exception(struct pt_regs *regs, int access)
{
- struct gmap *gmap;
- struct task_struct *tsk;
- struct mm_struct *mm;
struct vm_area_struct *vma;
- enum fault_type type;
- unsigned long trans_exc_code;
unsigned long address;
+ struct mm_struct *mm;
+ enum fault_type type;
unsigned int flags;
+ struct gmap *gmap;
vm_fault_t fault;
bool is_write;
- tsk = current;
/*
* The instruction that caused the program check has
* been nullified. Don't signal single step via SIGTRAP.
*/
clear_thread_flag(TIF_PER_TRAP);
-
if (kprobe_page_fault(regs, 14))
- return 0;
-
- mm = tsk->mm;
- trans_exc_code = regs->int_parm_long;
- address = trans_exc_code & __FAIL_ADDR_MASK;
- is_write = (trans_exc_code & store_indication) == 0x400;
-
- /*
- * Verify that the fault happened in user space, that
- * we are not in an interrupt and that there is a
- * user context.
- */
- fault = VM_FAULT_BADCONTEXT;
+ return;
+ mm = current->mm;
+ address = get_fault_address(regs);
+ is_write = fault_is_write(regs);
type = get_fault_type(regs);
switch (type) {
case KERNEL_FAULT:
- if (kfence_handle_page_fault(address, is_write, regs))
- return 0;
- goto out;
+ return handle_fault_error_nolock(regs, 0);
case USER_FAULT:
case GMAP_FAULT:
if (faulthandler_disabled() || !mm)
- goto out;
+ return handle_fault_error_nolock(regs, 0);
break;
}
-
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
flags = FAULT_FLAG_DEFAULT;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
- if (access == VM_WRITE || is_write)
+ if (is_write)
+ access = VM_WRITE;
+ if (access == VM_WRITE)
flags |= FAULT_FLAG_WRITE;
- mmap_read_lock(mm);
+ if (!(flags & FAULT_FLAG_USER))
+ goto lock_mmap;
+ vma = lock_vma_under_rcu(mm, address);
+ if (!vma)
+ goto lock_mmap;
+ if (!(vma->vm_flags & access)) {
+ vma_end_read(vma);
+ goto lock_mmap;
+ }
+ fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
+ if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
+ vma_end_read(vma);
+ if (!(fault & VM_FAULT_RETRY)) {
+ count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+ if (unlikely(fault & VM_FAULT_ERROR))
+ goto error;
+ return;
+ }
+ count_vm_vma_lock_event(VMA_LOCK_RETRY);
+ if (fault & VM_FAULT_MAJOR)
+ flags |= FAULT_FLAG_TRIED;
+ /* Quick path to respond to signals */
+ if (fault_signal_pending(fault, regs)) {
+ if (!user_mode(regs))
+ handle_fault_error_nolock(regs, 0);
+ return;
+ }
+lock_mmap:
+ mmap_read_lock(mm);
gmap = NULL;
if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) {
- gmap = (struct gmap *) S390_lowcore.gmap;
+ gmap = (struct gmap *)S390_lowcore.gmap;
current->thread.gmap_addr = address;
current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE);
current->thread.gmap_int_code = regs->int_code & 0xffff;
address = __gmap_translate(gmap, address);
- if (address == -EFAULT) {
- fault = VM_FAULT_BADMAP;
- goto out_up;
- }
+ if (address == -EFAULT)
+ return handle_fault_error(regs, SEGV_MAPERR);
if (gmap->pfault_enabled)
flags |= FAULT_FLAG_RETRY_NOWAIT;
}
-
retry:
- fault = VM_FAULT_BADMAP;
vma = find_vma(mm, address);
if (!vma)
- goto out_up;
-
+ return handle_fault_error(regs, SEGV_MAPERR);
if (unlikely(vma->vm_start > address)) {
if (!(vma->vm_flags & VM_GROWSDOWN))
- goto out_up;
- if (expand_stack(vma, address))
- goto out_up;
+ return handle_fault_error(regs, SEGV_MAPERR);
+ vma = expand_stack(mm, address);
+ if (!vma)
+ return handle_fault_error_nolock(regs, SEGV_MAPERR);
}
-
- /*
- * Ok, we have a good vm_area for this memory access, so
- * we can handle it..
- */
- fault = VM_FAULT_BADACCESS;
if (unlikely(!(vma->vm_flags & access)))
- goto out_up;
-
- if (is_vm_hugetlb_page(vma))
- address &= HPAGE_MASK;
- /*
- * If for any reason at all we couldn't handle the fault,
- * make sure we exit gracefully rather than endlessly redo
- * the fault.
- */
+ return handle_fault_error(regs, SEGV_ACCERR);
fault = handle_mm_fault(vma, address, flags, regs);
if (fault_signal_pending(fault, regs)) {
- fault = VM_FAULT_SIGNAL;
if (flags & FAULT_FLAG_RETRY_NOWAIT)
- goto out_up;
- goto out;
+ mmap_read_unlock(mm);
+ if (!user_mode(regs))
+ handle_fault_error_nolock(regs, 0);
+ return;
+ }
+ /* The fault is fully completed (including releasing mmap lock) */
+ if (fault & VM_FAULT_COMPLETED) {
+ if (gmap) {
+ mmap_read_lock(mm);
+ goto gmap;
+ }
+ return;
+ }
+ if (unlikely(fault & VM_FAULT_ERROR)) {
+ mmap_read_unlock(mm);
+ goto error;
}
- if (unlikely(fault & VM_FAULT_ERROR))
- goto out_up;
-
if (fault & VM_FAULT_RETRY) {
- if (IS_ENABLED(CONFIG_PGSTE) && gmap &&
- (flags & FAULT_FLAG_RETRY_NOWAIT)) {
+ if (IS_ENABLED(CONFIG_PGSTE) && gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
/*
- * FAULT_FLAG_RETRY_NOWAIT has been set, mmap_lock has
- * not been released
+ * FAULT_FLAG_RETRY_NOWAIT has been set,
+ * mmap_lock has not been released
*/
current->thread.gmap_pfault = 1;
- fault = VM_FAULT_PFAULT;
- goto out_up;
+ return handle_fault_error(regs, 0);
}
flags &= ~FAULT_FLAG_RETRY_NOWAIT;
flags |= FAULT_FLAG_TRIED;
mmap_read_lock(mm);
goto retry;
}
+gmap:
if (IS_ENABLED(CONFIG_PGSTE) && gmap) {
address = __gmap_link(gmap, current->thread.gmap_addr,
address);
- if (address == -EFAULT) {
- fault = VM_FAULT_BADMAP;
- goto out_up;
- }
+ if (address == -EFAULT)
+ return handle_fault_error(regs, SEGV_MAPERR);
if (address == -ENOMEM) {
fault = VM_FAULT_OOM;
- goto out_up;
+ mmap_read_unlock(mm);
+ goto error;
}
}
- fault = 0;
-out_up:
mmap_read_unlock(mm);
-out:
- return fault;
+ return;
+error:
+ if (fault & VM_FAULT_OOM) {
+ if (!user_mode(regs))
+ handle_fault_error_nolock(regs, 0);
+ else
+ pagefault_out_of_memory();
+ } else if (fault & VM_FAULT_SIGSEGV) {
+ if (!user_mode(regs))
+ handle_fault_error_nolock(regs, 0);
+ else
+ do_sigsegv(regs, SEGV_MAPERR);
+ } else if (fault & VM_FAULT_SIGBUS) {
+ if (!user_mode(regs))
+ handle_fault_error_nolock(regs, 0);
+ else
+ do_sigbus(regs);
+ } else {
+ BUG();
+ }
}
void do_protection_exception(struct pt_regs *regs)
{
- unsigned long trans_exc_code;
- int access;
- vm_fault_t fault;
+ union teid teid = { .val = regs->int_parm_long };
- trans_exc_code = regs->int_parm_long;
/*
* Protection exceptions are suppressing, decrement psw address.
* The exception to this rule are aborted transactions, for these
@@ -490,281 +458,50 @@ void do_protection_exception(struct pt_regs *regs)
* as a special case because the translation exception code
* field is not guaranteed to contain valid data in this case.
*/
- if (unlikely(!(trans_exc_code & 4))) {
- do_low_address(regs);
- return;
+ if (unlikely(!teid.b61)) {
+ if (user_mode(regs)) {
+ /* Low-address protection in user mode: cannot happen */
+ die(regs, "Low-address protection");
+ }
+ /*
+ * Low-address protection in kernel mode means
+ * NULL pointer write access in kernel mode.
+ */
+ return handle_fault_error_nolock(regs, 0);
}
- if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) {
- regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) |
- (regs->psw.addr & PAGE_MASK);
- access = VM_EXEC;
- fault = VM_FAULT_BADACCESS;
- } else {
- access = VM_WRITE;
- fault = do_exception(regs, access);
+ if (unlikely(MACHINE_HAS_NX && teid.b56)) {
+ regs->int_parm_long = (teid.addr * PAGE_SIZE) | (regs->psw.addr & PAGE_MASK);
+ return handle_fault_error_nolock(regs, SEGV_ACCERR);
}
- if (unlikely(fault))
- do_fault_error(regs, access, fault);
+ do_exception(regs, VM_WRITE);
}
NOKPROBE_SYMBOL(do_protection_exception);
void do_dat_exception(struct pt_regs *regs)
{
- int access;
- vm_fault_t fault;
-
- access = VM_ACCESS_FLAGS;
- fault = do_exception(regs, access);
- if (unlikely(fault))
- do_fault_error(regs, access, fault);
+ do_exception(regs, VM_ACCESS_FLAGS);
}
NOKPROBE_SYMBOL(do_dat_exception);
-#ifdef CONFIG_PFAULT
-/*
- * 'pfault' pseudo page faults routines.
- */
-static int pfault_disable;
-
-static int __init nopfault(char *str)
-{
- pfault_disable = 1;
- return 1;
-}
-
-__setup("nopfault", nopfault);
-
-struct pfault_refbk {
- u16 refdiagc;
- u16 reffcode;
- u16 refdwlen;
- u16 refversn;
- u64 refgaddr;
- u64 refselmk;
- u64 refcmpmk;
- u64 reserved;
-} __attribute__ ((packed, aligned(8)));
-
-static struct pfault_refbk pfault_init_refbk = {
- .refdiagc = 0x258,
- .reffcode = 0,
- .refdwlen = 5,
- .refversn = 2,
- .refgaddr = __LC_LPP,
- .refselmk = 1ULL << 48,
- .refcmpmk = 1ULL << 48,
- .reserved = __PF_RES_FIELD
-};
-
-int pfault_init(void)
-{
- int rc;
-
- if (pfault_disable)
- return -1;
- diag_stat_inc(DIAG_STAT_X258);
- asm volatile(
- " diag %1,%0,0x258\n"
- "0: j 2f\n"
- "1: la %0,8\n"
- "2:\n"
- EX_TABLE(0b,1b)
- : "=d" (rc)
- : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc");
- return rc;
-}
-
-static struct pfault_refbk pfault_fini_refbk = {
- .refdiagc = 0x258,
- .reffcode = 1,
- .refdwlen = 5,
- .refversn = 2,
-};
-
-void pfault_fini(void)
-{
-
- if (pfault_disable)
- return;
- diag_stat_inc(DIAG_STAT_X258);
- asm volatile(
- " diag %0,0,0x258\n"
- "0: nopr %%r7\n"
- EX_TABLE(0b,0b)
- : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc");
-}
-
-static DEFINE_SPINLOCK(pfault_lock);
-static LIST_HEAD(pfault_list);
-
-#define PF_COMPLETE 0x0080
-
-/*
- * The mechanism of our pfault code: if Linux is running as guest, runs a user
- * space process and the user space process accesses a page that the host has
- * paged out we get a pfault interrupt.
- *
- * This allows us, within the guest, to schedule a different process. Without
- * this mechanism the host would have to suspend the whole virtual cpu until
- * the page has been paged in.
- *
- * So when we get such an interrupt then we set the state of the current task
- * to uninterruptible and also set the need_resched flag. Both happens within
- * interrupt context(!). If we later on want to return to user space we
- * recognize the need_resched flag and then call schedule(). It's not very
- * obvious how this works...
- *
- * Of course we have a lot of additional fun with the completion interrupt (->
- * host signals that a page of a process has been paged in and the process can
- * continue to run). This interrupt can arrive on any cpu and, since we have
- * virtual cpus, actually appear before the interrupt that signals that a page
- * is missing.
- */
-static void pfault_interrupt(struct ext_code ext_code,
- unsigned int param32, unsigned long param64)
-{
- struct task_struct *tsk;
- __u16 subcode;
- pid_t pid;
-
- /*
- * Get the external interruption subcode & pfault initial/completion
- * signal bit. VM stores this in the 'cpu address' field associated
- * with the external interrupt.
- */
- subcode = ext_code.subcode;
- if ((subcode & 0xff00) != __SUBCODE_MASK)
- return;
- inc_irq_stat(IRQEXT_PFL);
- /* Get the token (= pid of the affected task). */
- pid = param64 & LPP_PID_MASK;
- rcu_read_lock();
- tsk = find_task_by_pid_ns(pid, &init_pid_ns);
- if (tsk)
- get_task_struct(tsk);
- rcu_read_unlock();
- if (!tsk)
- return;
- spin_lock(&pfault_lock);
- if (subcode & PF_COMPLETE) {
- /* signal bit is set -> a page has been swapped in by VM */
- if (tsk->thread.pfault_wait == 1) {
- /* Initial interrupt was faster than the completion
- * interrupt. pfault_wait is valid. Set pfault_wait
- * back to zero and wake up the process. This can
- * safely be done because the task is still sleeping
- * and can't produce new pfaults. */
- tsk->thread.pfault_wait = 0;
- list_del(&tsk->thread.list);
- wake_up_process(tsk);
- put_task_struct(tsk);
- } else {
- /* Completion interrupt was faster than initial
- * interrupt. Set pfault_wait to -1 so the initial
- * interrupt doesn't put the task to sleep.
- * If the task is not running, ignore the completion
- * interrupt since it must be a leftover of a PFAULT
- * CANCEL operation which didn't remove all pending
- * completion interrupts. */
- if (task_is_running(tsk))
- tsk->thread.pfault_wait = -1;
- }
- } else {
- /* signal bit not set -> a real page is missing. */
- if (WARN_ON_ONCE(tsk != current))
- goto out;
- if (tsk->thread.pfault_wait == 1) {
- /* Already on the list with a reference: put to sleep */
- goto block;
- } else if (tsk->thread.pfault_wait == -1) {
- /* Completion interrupt was faster than the initial
- * interrupt (pfault_wait == -1). Set pfault_wait
- * back to zero and exit. */
- tsk->thread.pfault_wait = 0;
- } else {
- /* Initial interrupt arrived before completion
- * interrupt. Let the task sleep.
- * An extra task reference is needed since a different
- * cpu may set the task state to TASK_RUNNING again
- * before the scheduler is reached. */
- get_task_struct(tsk);
- tsk->thread.pfault_wait = 1;
- list_add(&tsk->thread.list, &pfault_list);
-block:
- /* Since this must be a userspace fault, there
- * is no kernel task state to trample. Rely on the
- * return to userspace schedule() to block. */
- __set_current_state(TASK_UNINTERRUPTIBLE);
- set_tsk_need_resched(tsk);
- set_preempt_need_resched();
- }
- }
-out:
- spin_unlock(&pfault_lock);
- put_task_struct(tsk);
-}
-
-static int pfault_cpu_dead(unsigned int cpu)
-{
- struct thread_struct *thread, *next;
- struct task_struct *tsk;
-
- spin_lock_irq(&pfault_lock);
- list_for_each_entry_safe(thread, next, &pfault_list, list) {
- thread->pfault_wait = 0;
- list_del(&thread->list);
- tsk = container_of(thread, struct task_struct, thread);
- wake_up_process(tsk);
- put_task_struct(tsk);
- }
- spin_unlock_irq(&pfault_lock);
- return 0;
-}
-
-static int __init pfault_irq_init(void)
-{
- int rc;
-
- rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
- if (rc)
- goto out_extint;
- rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
- if (rc)
- goto out_pfault;
- irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
- cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead",
- NULL, pfault_cpu_dead);
- return 0;
-
-out_pfault:
- unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
-out_extint:
- pfault_disable = 1;
- return rc;
-}
-early_initcall(pfault_irq_init);
-
-#endif /* CONFIG_PFAULT */
-
#if IS_ENABLED(CONFIG_PGSTE)
void do_secure_storage_access(struct pt_regs *regs)
{
- unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK;
+ union teid teid = { .val = regs->int_parm_long };
+ unsigned long addr = get_fault_address(regs);
struct vm_area_struct *vma;
struct mm_struct *mm;
struct page *page;
+ struct gmap *gmap;
int rc;
/*
- * bit 61 tells us if the address is valid, if it's not we
- * have a major problem and should stop the kernel or send a
- * SIGSEGV to the process. Unfortunately bit 61 is not
- * reliable without the misc UV feature so we need to check
- * for that as well.
+ * Bit 61 indicates if the address is valid, if it is not the
+ * kernel should be stopped or SIGSEGV should be sent to the
+ * process. Bit 61 is not reliable without the misc UV feature,
+ * therefore this needs to be checked too.
*/
- if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
- !test_bit_inv(61, &regs->int_parm_long)) {
+ if (uv_has_feature(BIT_UV_FEAT_MISC) && !teid.b61) {
/*
* When this happens, userspace did something that it
* was not supposed to do, e.g. branching into secure
@@ -774,24 +511,28 @@ void do_secure_storage_access(struct pt_regs *regs)
send_sig(SIGSEGV, current, 0);
return;
}
-
/*
- * The kernel should never run into this case and we
- * have no way out of this situation.
+ * The kernel should never run into this case and
+ * there is no way out of this situation.
*/
panic("Unexpected PGM 0x3d with TEID bit 61=0");
}
-
switch (get_fault_type(regs)) {
+ case GMAP_FAULT:
+ mm = current->mm;
+ gmap = (struct gmap *)S390_lowcore.gmap;
+ mmap_read_lock(mm);
+ addr = __gmap_translate(gmap, addr);
+ mmap_read_unlock(mm);
+ if (IS_ERR_VALUE(addr))
+ return handle_fault_error_nolock(regs, SEGV_MAPERR);
+ fallthrough;
case USER_FAULT:
mm = current->mm;
mmap_read_lock(mm);
vma = find_vma(mm, addr);
- if (!vma) {
- mmap_read_unlock(mm);
- do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
- break;
- }
+ if (!vma)
+ return handle_fault_error(regs, SEGV_MAPERR);
page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET);
if (IS_ERR_OR_NULL(page)) {
mmap_read_unlock(mm);
@@ -811,25 +552,19 @@ void do_secure_storage_access(struct pt_regs *regs)
if (rc)
BUG();
break;
- case GMAP_FAULT:
default:
- do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
- WARN_ON_ONCE(1);
+ unreachable();
}
}
NOKPROBE_SYMBOL(do_secure_storage_access);
void do_non_secure_storage_access(struct pt_regs *regs)
{
- unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK;
struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
+ unsigned long gaddr = get_fault_address(regs);
- if (get_fault_type(regs) != GMAP_FAULT) {
- do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
- WARN_ON_ONCE(1);
- return;
- }
-
+ if (WARN_ON_ONCE(get_fault_type(regs) != GMAP_FAULT))
+ return handle_fault_error_nolock(regs, SEGV_MAPERR);
if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL)
send_sig(SIGSEGV, current, 0);
}
@@ -837,6 +572,16 @@ NOKPROBE_SYMBOL(do_non_secure_storage_access);
void do_secure_storage_violation(struct pt_regs *regs)
{
+ struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
+ unsigned long gaddr = get_fault_address(regs);
+
+ /*
+ * If the VM has been rebooted, its address space might still contain
+ * secure pages from the previous boot.
+ * Clear the page so it can be reused.
+ */
+ if (!gmap_destroy_page(gmap, gaddr))
+ return;
/*
* Either KVM messed up the secure guest mapping or the same
* page is mapped into multiple secure guests.
@@ -844,9 +589,8 @@ void do_secure_storage_violation(struct pt_regs *regs)
* This exception is only triggered when a guest 2 is running
* and can therefore never occur in kernel context.
*/
- printk_ratelimited(KERN_WARNING
- "Secure storage violation in task: %s, pid %d\n",
- current->comm, current->pid);
+ pr_warn_ratelimited("Secure storage violation in task: %s, pid %d\n",
+ current->comm, current->pid);
send_sig(SIGSEGV, current, 0);
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.