Hi Richard,
On 28/06/17 16:56, Richard Earnshaw (lists) wrote:
On 20/06/17 16:01, Thomas Preudhomme wrote:
Hi,
Function cmse_nonsecure_entry_clear_before_return has code to deal with
high VFP register (D16-D31) while ARMv8-M Baseline and Mainline both do
not support more than 16 double VFP registers (D0-D15). This makes this
security-sensitive code harder to read for not much benefit since
libcall for cmse_nonsecure_call functions do not deal with those high
VFP registers anyway.
This commit gets rid of this code for simplicity and fixes 2 issues in
the same function:
- stop the first loop when reaching maxregno to avoid dealing with VFP
registers if targetting Thumb-1 or using -mfloat-abi=soft
- include maxregno in that loop
This is silently baking in dangerous assumptions about GCC's internal
numbering of the registers. That's not a good idea from a long-term
portability perspective.
At the very least you need to assert that all the interesting registers
are numbered in the range 0..63; but ideally the code should just handle
pretty much any assignment of internal register numbers.
Well there is already this:
gcc_assert ((unsigned) maxregno <= sizeof (to_clear_mask) * __CHAR_BIT__);
Did you consider using sbitmaps rather than doing all the multi-word
stuff by steam?
No but am happy to. I'll respin the patch.
Best regards,
Thomas
