Fix safe_syscall() on ppc64 host

Fix mmap() 0 length error case
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Merge remote-tracking branch 'remotes/vivier2/tags/linux-user-for-3.0-pull-request' into staging

Fix safe_syscall() on ppc64 host
Fix mmap() 0 length error case

# gpg: Signature made Tue 31 Jul 2018 09:41:07 BST
# gpg:                using RSA key F30C38BD3F2FBE3C
# gpg: Good signature from "Laurent Vivier <lvivier@redhat.com>"
# gpg:                 aka "Laurent Vivier <laurent@vivier.eu>"
# gpg:                 aka "Laurent Vivier (Red Hat) <lvivier@redhat.com>"
# Primary key fingerprint: CD2F 75DD C8E3 A4DC 2E4F  5173 F30C 38BD 3F2F BE3C

* remotes/vivier2/tags/linux-user-for-3.0-pull-request:
  linux-user: ppc64: don't use volatile register during safe_syscall
  tests: add check_invalid_maps to test-mmap
  linux-user/mmap.c: handle invalid len maps correctly

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

linux-user/host/ppc64/safe-syscall.inc.S

@@ -49,7 +49,9 @@ safe_syscall_base:
 	 *               and returns the result in r3
 	 * Shuffle everything around appropriately.
 	 */
-	mr	11, 3	/* signal_pending */
+	std     14, 16(1) /* Preserve r14 in SP+16 */
+	.cfi_offset 14, 16
+	mr	14, 3	/* signal_pending */
 	mr	0, 4	/* syscall number */
 	mr	3, 5	/* syscall arguments */
 	mr	4, 6
@@ -67,12 +69,13 @@ safe_syscall_base:
 	 */
 safe_syscall_start:
 	/* if signal_pending is non-zero, don't do the call */
-	lwz	12, 0(11)
+	lwz	12, 0(14)
 	cmpwi	0, 12, 0
 	bne-	0f
 	sc
 safe_syscall_end:
 	/* code path when we did execute the syscall */
+	ld 14, 16(1) /* restore r14 to its original value */
 	bnslr+
 
 	/* syscall failed; return negative errno */
@@ -81,6 +84,7 @@ safe_syscall_end:
 
 	/* code path when we didn't execute the syscall */
 0:	addi	3, 0, -TARGET_ERESTARTSYS
+	ld 14, 16(1) /* restore r14 to its orginal value */
 	blr
 	.cfi_endproc
 

linux-user/mmap.c

@@ -391,14 +391,23 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
     }
 #endif
 
-    if (offset & ~TARGET_PAGE_MASK) {
+    if (!len) {
         errno = EINVAL;
         goto fail;
     }
 
+    /* Also check for overflows... */
     len = TARGET_PAGE_ALIGN(len);
-    if (len == 0)
-        goto the_end;
+    if (!len) {
+        errno = ENOMEM;
+        goto fail;
+    }
+
+    if (offset & ~TARGET_PAGE_MASK) {
+        errno = EINVAL;
+        goto fail;
+    }
+
     real_start = start & qemu_host_page_mask;
     host_offset = offset & qemu_host_page_mask;
 

tests/tcg/multiarch/test-mmap.c

@@ -27,7 +27,7 @@
 #include <stdint.h>
 #include <string.h>
 #include <unistd.h>
-
+#include <errno.h>
 #include <sys/mman.h>
 
 #define D(x)
@@ -435,6 +435,25 @@ void checked_write(int fd, const void *buf, size_t count)
     fail_unless(rc == count);
 }
 
+void check_invalid_mmaps(void)
+{
+    unsigned char *addr;
+
+    /* Attempt to map a zero length page.  */
+    addr = mmap(NULL, 0, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    fprintf(stdout, "%s addr=%p", __func__, (void *)addr);
+    fail_unless(addr == MAP_FAILED);
+    fail_unless(errno == EINVAL);
+
+    /* Attempt to map a over length page.  */
+    addr = mmap(NULL, -4, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    fprintf(stdout, "%s addr=%p", __func__, (void *)addr);
+    fail_unless(addr == MAP_FAILED);
+    fail_unless(errno == ENOMEM);
+
+    fprintf(stdout, " passed\n");
+}
+
 int main(int argc, char **argv)
 {
 	char tempname[] = "/tmp/.cmmapXXXXXX";
@@ -476,6 +495,7 @@ int main(int argc, char **argv)
 	check_file_fixed_mmaps();
 	check_file_fixed_eof_mmaps();
 	check_file_unfixed_eof_mmaps();
+	check_invalid_mmaps();
 
 	/* Fails at the moment.  */
 	/* check_aligned_anonymous_fixed_mmaps_collide_with_host(); */