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Message-ID: <87lhmobvuu.fsf@linux.vnet.ibm.com>
Date: Wed, 03 Dec 2014 20:53:37 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Mel Gorman <mgorman@...e.de>,
Linux Kernel <linux-kernel@...r.kernel.org>,
Linux-MM <linux-mm@...ck.org>,
LinuxPPC-dev <linuxppc-dev@...ts.ozlabs.org>,
Hugh Dickins <hughd@...gle.com>, Dave Jones <davej@...hat.com>,
Rik van Riel <riel@...hat.com>,
Ingo Molnar <mingo@...hat.com>,
Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
Sasha Levin <sasha.levin@...cle.com>,
Paul Mackerras <paulus@...ba.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 03/10] mm: Convert p[te|md]_numa users to p[te|md]_protnone_numa
Benjamin Herrenschmidt <benh@...nel.crashing.org> writes:
> On Tue, 2014-12-02 at 12:57 +0530, Aneesh Kumar K.V wrote:
>> Now, hash_preload can possibly insert an hpte in hash page table even if
>> the access is not allowed by the pte permissions. But i guess even that
>> is ok. because we will fault again, end-up calling hash_page_mm where we
>> handle that part correctly.
>
> I think we need a test case...
>
I ran the subpageprot test that Paul had written. I modified it to ran
with selftest.
commit 0cd3756bce6880a13de49406ce5c8537712c9bf8
Author: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
Date: Wed Dec 3 20:40:06 2014 +0530
selftest/ppc: Add subpage protection self test.
Originally written by Paul Mackerras <paulus@...ba.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
diff --git a/tools/testing/selftests/powerpc/mm/Makefile b/tools/testing/selftests/powerpc/mm/Makefile
index 357ccbd6bad9..fb00c6f7d675 100644
--- a/tools/testing/selftests/powerpc/mm/Makefile
+++ b/tools/testing/selftests/powerpc/mm/Makefile
@@ -1,7 +1,7 @@
noarg:
$(MAKE) -C ../
-PROGS := hugetlb_vs_thp_test
+PROGS := hugetlb_vs_thp_test subpage_prot
all: $(PROGS)
diff --git a/tools/testing/selftests/powerpc/mm/subpage_prot.c b/tools/testing/selftests/powerpc/mm/subpage_prot.c
new file mode 100644
index 000000000000..1efeafc2e175
--- /dev/null
+++ b/tools/testing/selftests/powerpc/mm/subpage_prot.c
@@ -0,0 +1,150 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <sys/ptrace.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <ucontext.h>
+#include <assert.h>
+
+#include "utils.h"
+
+void *mallocblock;
+unsigned long mallocsize;
+void *fileblock;
+off_t filesize;
+
+int in_test;
+volatile int faulted;
+volatile void *dar;
+int errors;
+
+static void segv(int signum, siginfo_t *info, void *ctxt_v)
+{
+ ucontext_t *ctxt = (ucontext_t *)ctxt_v;
+ struct pt_regs *regs = ctxt->uc_mcontext.regs;
+
+ if (!in_test) {
+ fprintf(stderr, "Segfault outside of test !\n");
+ exit(1);
+ }
+ faulted = 1;
+ dar = (void *)regs->dar;
+ regs->nip += 4;
+}
+
+static inline void do_read(const volatile void *addr)
+{
+ int ret;
+ asm volatile("lwz %0,0(%1); twi 0,%0,0; isync;\n"
+ : "=r" (ret) : "r" (addr) : "memory");
+}
+
+static inline void do_write(const volatile void *addr)
+{
+ int val = 0x1234567;
+ asm volatile("stw %0,0(%1); sync; \n"
+ : : "r" (val), "r" (addr) : "memory");
+}
+
+static inline void check_faulted(void *addr, long page, long subpage, int write)
+{
+ int want_fault = (subpage == ((page + 3) % 16));
+
+ if (write)
+ want_fault |= (subpage == ((page + 1) % 16));
+
+ if (faulted != want_fault) {
+ printf("Failed at 0x%p (p=%ld,sp=%ld,w=%d), want=%s, got=%s !\n",
+ addr, page, subpage, write,
+ want_fault ? "fault" : "pass",
+ faulted ? "fault" : "pass");
+ ++errors;
+ }
+ if (faulted) {
+ if (dar != addr) {
+ printf("Fault expected at 0x%p and happened at 0x%p !\n",
+ addr, dar);
+ }
+ faulted = 0;
+ asm volatile("sync" : : : "memory");
+ }
+}
+
+static int run_test(void *addr, unsigned long size)
+{
+ unsigned int *map;
+ long i, j, pages, err;
+
+ pages = size / 0x10000;
+ map = malloc(pages * 4);
+ assert(map);
+
+ /* for each page, mark subpage i % 16 read only and subpage
+ * (i + 3) % 16 inaccessible
+ */
+ for (i = 0; i < pages; i++)
+ map[i] = (0x40000000 >> (((i + 1) * 2) % 32)) |
+ (0xc0000000 >> (((i + 3) * 2) % 32));
+ err = syscall(310, addr, size, map);
+ if (err) {
+ perror("subpage_perm");
+ return 1;
+ }
+ free(map);
+
+ in_test = 1;
+ errors = 0;
+ for (i = 0; i < pages; i++)
+ for (j = 0; j < 16; j++, addr += 0x1000) {
+ do_read(addr);
+ check_faulted(addr, i, j, 0);
+ do_write(addr);
+ check_faulted(addr, i, j, 1);
+ }
+ in_test = 0;
+ if (errors) {
+ printf("%d errors detected\n", errors);
+ return 1;
+ }
+ printf("OK\n");
+ return 0;
+}
+
+int test_main(void)
+{
+ unsigned long align;
+
+ if (getpagesize() != 0x10000) {
+ fprintf(stderr, "Kernel page size must be 64K!\n");
+ return 1;
+ }
+
+ struct sigaction act = {
+ .sa_sigaction = segv,
+ .sa_flags = SA_SIGINFO
+ };
+ sigaction(SIGSEGV, &act, NULL);
+
+ mallocsize = 4*16*1024*1024;
+ posix_memalign(&mallocblock, 64*1024, mallocsize);
+ assert(mallocblock);
+ align = (unsigned long)mallocblock;
+ if (align & 0xffff)
+ align = (align | 0xffff) + 1;
+ mallocblock = (void *)align;
+
+ printf("allocated malloc block of 0x%lx bytes at 0x%p\n",
+ mallocsize, mallocblock);
+
+ printf("testing malloc block...\n");
+ return run_test(mallocblock, mallocsize);
+}
+
+int main(void)
+{
+ return test_harness(test_main, "subpage_prot");
+}
--
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