In case of nested user of the FPU or vector registers in the kernel
the current code uses the mask of the FPU/vector registers of the
previous contexts to decide which registers to save and restore.
E.g. if the previous context used KERNEL_VXR_V0V7 and the next
context wants to use KERNEL_VXR_V24V31 the first 8 vector registers
are stored to the FPU state structure. But this is not necessary
as the next context does not use these registers.
Rework the FPU/vector register save and restore code. The new code
does a few things differently:
1) A lowcore field is used instead of a per-cpu variable.
2) The kernel_fpu_end function now has two parameters just like
kernel_fpu_begin. The register flags are required by both
functions to save / restore the minimal register set.
3) The inline functions kernel_fpu_begin/kernel_fpu_end now do the
update of the register masks. If the user space FPU registers
have already been stored neither save_fpu_regs nor the
__kernel_fpu_begin/__kernel_fpu_end functions have to be called
for the first context. In this case kernel_fpu_begin adds 7
instructions and kernel_fpu_end adds 4 instructions.
3) The inline assemblies in __kernel_fpu_begin / __kernel_fpu_end
to save / restore the vector registers are simplified a bit.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The current prealign logic will fail for sizes < alignment,
as the new datalen passed to the vector function is smaller
than zero. Being a size_t this gets wrapped to a huge
number causing memory overruns and wrong data.
Let's add an early exit if the size is smaller than the minimal
size with alignment. This will also avoid calling the software
fallback twice for all sizes smaller than the minimum size
(prealign + remaining)
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Fixes: f848dbd3bc ("s390/crc32-vx: add crypto API module for optimized CRC-32 algorithms")
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add a crypto API module to access the vector extension based CRC-32
implementations. Users can request the optimized implementation through
the shash crypto API interface.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
