On Mon, May 14, 2018 at 04:49:43PM +0100, Maciej W. Rozycki wrote:
> Check the TIF_32BIT_FPREGS task setting of the tracee rather than the
> tracer in determining the layout of floating-point general registers in
> the floating-point context, correcting access to odd-numbered registers
> for o32 tracees where the setting disagrees between the two processes.
>
> Cc: stable@xxxxxxxxxxxxxxx # 3.14+
> Fixes: 597ce1723e0f ("MIPS: Support for 64-bit FP with O32 binaries")
> Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxx>
> ---
> Hi,
>
> These are not the usual requests used by GDB to access the floating-point
> context, which is likely why it went unnoticed so long. They are only
> used as a fallback in the case where PTRACE_GETFPREGS and PTRACE_SETFPREGS
> requests are not supported, i.e. with ancient kernels.
>
> However to verify an unrelated GDB bug fix I have tweaked GDB to always
> use PTRACE_PEEKUSR and PTRACE_POKEUSR, and then discovered this issue in
> native GDB regression testing, as it showed regressions from corrupt FGR
> contents across numerous tests compared to the usual results. This fix
> removed those regressions then.
>
> Not being typically used does not mean we ought to keep the interface
> broken. Therefore please apply.
Looks good. Applied to fixes branch for 4.17.
Thanks
James
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