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[Qemu-devel] [PATCH 2/3] exec.c: Don't accidentally sign-extend 4-byte l
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH 2/3] exec.c: Don't accidentally sign-extend 4-byte loads in subpage_read() |
Date: |
Mon, 11 Jun 2018 18:10:06 +0100 |
In subpage_read() we perform a load of the data into a local buffer
which we then access using ldub_p(), lduw_p(), ldl_p() or ldq_p()
depending on its size, storing the result into the uint64_t *data.
Since ldl_p() returns an 'int', this means that for the 4-byte
case we will sign-extend the data, whereas for 1 and 2 byte
reads we zero-extend it.
This ought not to matter since the caller will likely ignore values in
the high bytes of the data, but add a cast so that we're consistent.
Signed-off-by: Peter Maydell <address@hidden>
---
exec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/exec.c b/exec.c
index 9cbba6adcd3..90b47cde7b1 100644
--- a/exec.c
+++ b/exec.c
@@ -2747,7 +2747,7 @@ static MemTxResult subpage_read(void *opaque, hwaddr
addr, uint64_t *data,
*data = lduw_p(buf);
return MEMTX_OK;
case 4:
- *data = ldl_p(buf);
+ *data = (uint32_t)ldl_p(buf);
return MEMTX_OK;
case 8:
*data = ldq_p(buf);
--
2.17.1
- [Qemu-devel] [PATCH 0/3] Add ldn_*_p() and stn_*_p() and use them in exec.c, Peter Maydell, 2018/06/11
- [Qemu-devel] [PATCH 1/3] bswap: Add new stn_*_p() and ldn_*_p() memory access functions, Peter Maydell, 2018/06/11
- [Qemu-devel] [PATCH 3/3] exec.c: Use stn_p() and ldn_p() instead of explicit switches, Peter Maydell, 2018/06/11
- [Qemu-devel] [PATCH 2/3] exec.c: Don't accidentally sign-extend 4-byte loads in subpage_read(),
Peter Maydell <=
- Re: [Qemu-devel] [PATCH 0/3] Add ldn_*_p() and stn_*_p() and use them in exec.c, no-reply, 2018/06/11
- Re: [Qemu-devel] [PATCH 0/3] Add ldn_*_p() and stn_*_p() and use them in exec.c, no-reply, 2018/06/11
- Re: [Qemu-devel] [PATCH 0/3] Add ldn_*_p() and stn_*_p() and use them in exec.c, Peter Maydell, 2018/06/15