[Qemu-devel] [PULL 0/1] linux-user: fix file offset for preadv/pwritev

[Qemu-devel] [PULL 0/1] linux-user: fix file offset for preadv/pwritev

[Max Filippov]

Hi Peter,

please pull the following linux-user fix for QEMU-2.12.

The following changes since commit 9abfc88af3ffd3b33c7fab4471da86462ee71d95:

  Merge remote-tracking branch 'remotes/xtensa/tags/20180402-xtensa' into staging (2018-04-03 19:02:46 +0100)

are available in the git repository at:

  git://github.com/OSLL/qemu-xtensa.git tags/20180409-xtensa

for you to fetch changes up to 9ac225171c9d6b2a1cba35a94ae7eeaa0106cf7d:

  linux-user: fix preadv/pwritev offsets (2018-04-09 18:57:49 -0700)

----------------------------------------------------------------
Fix file offset for preadv/pwritev linux-user syscalls.

----------------------------------------------------------------
Max Filippov (1):
      linux-user: fix preadv/pwritev offsets

 linux-user/syscall.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

-- 
Thanks.
-- Max

[Qemu-devel] [PULL 1/1] linux-user: fix preadv/pwritev offsets

[Max Filippov]

preadv/pwritev accept low and high parts of file offset in two separate
parameters. When host bitness doesn't match guest bitness these parts
must be appropriately recombined.
Introduce target_to_host_low_high that does this recombination and use
it in preadv/pwritev syscalls.

This fixes glibc testsuite test misc/tst-preadvwritev64.

Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 linux-user/syscall.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 5ef517613577..0eab5cc6ade1 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -3386,6 +3386,23 @@ static abi_long do_getsockopt(int sockfd, int level, int optname,
     return ret;
 }
 
+/* Convert target low/high pair representing file offset into the host
+ * low/high pair. This function doesn't handle offsets bigger than 64 bits
+ * as the kernel doesn't handle them either.
+ */
+static void target_to_host_low_high(abi_ulong tlow,
+                                    abi_ulong thigh,
+                                    unsigned long *hlow,
+                                    unsigned long *hhigh)
+{
+    uint64_t off = tlow |
+        ((unsigned long long)thigh << TARGET_LONG_BITS / 2) <<
+        TARGET_LONG_BITS / 2;
+
+    *hlow = off;
+    *hhigh = (off >> HOST_LONG_BITS / 2) >> HOST_LONG_BITS / 2;
+}
+
 static struct iovec *lock_iovec(int type, abi_ulong target_addr,
                                 abi_ulong count, int copy)
 {
@@ -10449,7 +10466,10 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
         {
             struct iovec *vec = lock_iovec(VERIFY_WRITE, arg2, arg3, 0);
             if (vec != NULL) {
-                ret = get_errno(safe_preadv(arg1, vec, arg3, arg4, arg5));
+                unsigned long low, high;
+
+                target_to_host_low_high(arg4, arg5, &low, &high);
+                ret = get_errno(safe_preadv(arg1, vec, arg3, low, high));
                 unlock_iovec(vec, arg2, arg3, 1);
             } else {
                 ret = -host_to_target_errno(errno);
@@ -10462,7 +10482,10 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
         {
             struct iovec *vec = lock_iovec(VERIFY_READ, arg2, arg3, 1);
             if (vec != NULL) {
-                ret = get_errno(safe_pwritev(arg1, vec, arg3, arg4, arg5));
+                unsigned long low, high;
+
+                target_to_host_low_high(arg4, arg5, &low, &high);
+                ret = get_errno(safe_pwritev(arg1, vec, arg3, low, high));
                 unlock_iovec(vec, arg2, arg3, 0);
             } else {
                 ret = -host_to_target_errno(errno);
-- 
2.11.0

Re: [Qemu-devel] [PULL 1/1] linux-user: fix preadv/pwritev offsets

[Richard Henderson]

On 04/10/2018 12:17 PM, Max Filippov wrote:
> +    uint64_t off = tlow |
> +        ((unsigned long long)thigh << TARGET_LONG_BITS / 2) <<

There's a second instance of long long here; needs uint64_t.


r~

Re: [Qemu-devel] [PULL 1/1] linux-user: fix preadv/pwritev offsets

[Max Filippov]

On Mon, Apr 9, 2018 at 8:20 PM, Richard Henderson
<richard.henderson@linaro.org> wrote:
> On 04/10/2018 12:17 PM, Max Filippov wrote:
>> +    uint64_t off = tlow |
>> +        ((unsigned long long)thigh << TARGET_LONG_BITS / 2) <<
>
> There's a second instance of long long here; needs uint64_t.

Ehh, will fix.
BTW, why is uint64_t here better than unsigned long long? Just
shorter?

-- 
Thanks.
-- Max

Re: [Qemu-devel] [PULL 1/1] linux-user: fix preadv/pwritev offsets

[Richard Henderson]

On 04/10/2018 01:29 PM, Max Filippov wrote:
> On Mon, Apr 9, 2018 at 8:20 PM, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>> On 04/10/2018 12:17 PM, Max Filippov wrote:
>>> +    uint64_t off = tlow |
>>> +        ((unsigned long long)thigh << TARGET_LONG_BITS / 2) <<
>>
>> There's a second instance of long long here; needs uint64_t.
> 
> Ehh, will fix.
> BTW, why is uint64_t here better than unsigned long long? Just
> shorter?

Because it's more explicit about the number of bits we're talking about.


r~

Re: [Qemu-devel] [PULL 0/1] linux-user: fix file offset for preadv/pwritev

[Peter Maydell]

On 10 April 2018 at 03:17, Max Filippov <jcmvbkbc@gmail.com> wrote:
> Hi Peter,
>
> please pull the following linux-user fix for QEMU-2.12.
>
> The following changes since commit 9abfc88af3ffd3b33c7fab4471da86462ee71d95:
>
>   Merge remote-tracking branch 'remotes/xtensa/tags/20180402-xtensa' into staging (2018-04-03 19:02:46 +0100)
>
> are available in the git repository at:
>
>   git://github.com/OSLL/qemu-xtensa.git tags/20180409-xtensa
>
> for you to fetch changes up to 9ac225171c9d6b2a1cba35a94ae7eeaa0106cf7d:
>
>   linux-user: fix preadv/pwritev offsets (2018-04-09 18:57:49 -0700)
>
> ----------------------------------------------------------------
> Fix file offset for preadv/pwritev linux-user syscalls.
>
> ----------------------------------------------------------------
> Max Filippov (1):
>       linux-user: fix preadv/pwritev offsets

Applied, thanks.

-- PMM