On Tue, 8 Jan 2019 at 22:46, David Gibson <da...@gibson.dropbear.id.au> wrote:
>
> From: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk>
>
> The VSX register array is a block of 64 128-bit registers where the first 32
> registers consist of the existing 64-bit FP registers extended to 128-bit
> using new VSR registers, and the last 32 registers are the VMX 128-bit
> registers as show below:
>
> 64-bit 64-bit
> +--------------------+--------------------+
> | FP0 | | VSR0
> +--------------------+--------------------+
> | FP1 | | VSR1
> +--------------------+--------------------+
> | ... | ... | ...
> +--------------------+--------------------+
> | FP30 | | VSR30
> +--------------------+--------------------+
> | FP31 | | VSR31
> +--------------------+--------------------+
> | VMX0 | VSR32
> +-----------------------------------------+
> | VMX1 | VSR33
> +-----------------------------------------+
> | ... | ...
> +-----------------------------------------+
> | VMX30 | VSR62
> +-----------------------------------------+
> | VMX31 | VSR63
> +-----------------------------------------+
>
> In order to allow for future conversion of VSX instructions to use TCG vector
> operations, recreate the same layout using an aligned version of the existing
> vsr register array.
>
> Since the old fpr and avr register arrays are removed, the existing callers
> must also be updated to use the correct offset in the vsr register array. This
> also includes switching the relevant VMState fields over to using subarrays
> to make sure that migration is preserved.
> @@ -281,15 +281,17 @@ static void save_user_regs(CPUPPCState *env, struct
> target_mcontext *frame)
> /* Save VSX second halves */
> if (env->insns_flags2 & PPC2_VSX) {
> uint64_t *vsregs = (uint64_t *)&frame->mc_vregs.altivec[34];
This line didn't change in this patch, but the code change seems
to have prompted Coverity to warn (CID 1396862):
illegal_address: &frame->mc_vregs.altivec[34] evaluates to an address that is
at byte offset 544 of an array of 528 bytes.
> @@ -393,16 +395,18 @@ static void restore_user_regs(CPUPPCState *env,
> /* Restore VSX second halves */
> if (env->insns_flags2 & PPC2_VSX) {
> uint64_t *vsregs = (uint64_t *)&frame->mc_vregs.altivec[34];
...and then CID 1396863 is the same issue for this line.
Is this legit, or a false-positive ?
thanks
-- PMM
