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Re: [Qemu-devel] [PATCH 2/3] exec.c: Don't accidentally sign-extend 4-by
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] exec.c: Don't accidentally sign-extend 4-byte loads in subpage_read() |
Date: |
Tue, 12 Jun 2018 10:58:26 -1000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 06/11/2018 07:10 AM, Peter Maydell wrote:
> 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>
> ---
Reviewed-by: Richard Henderson <address@hidden>
r~
- [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, 2018/06/11
- Re: [Qemu-devel] [PATCH 2/3] exec.c: Don't accidentally sign-extend 4-byte loads in subpage_read(),
Richard Henderson <=
- 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