Re: [PATCH 3/3] bpf powerpc: add support for bpf constant blinding

On 09/23/2016 10:35 PM, Naveen N. Rao wrote:

In line with similar support for other architectures by Daniel Borkmann.

'MOD Default X' from test_bpf without constant blinding:
84 bytes emitted from JIT compiler (pass:3, flen:7)
d0000000058a4688 + <x>:
    0:	nop
    4:	nop
    8:	std     r27,-40(r1)
    c:	std     r28,-32(r1)
   10:	xor     r8,r8,r8
   14:	xor     r28,r28,r28
   18:	mr      r27,r3
   1c:	li      r8,66
   20:	cmpwi   r28,0
   24:	bne     0x0000000000000030
   28:	li      r8,0
   2c:	b       0x0000000000000044
   30:	divwu   r9,r8,r28
   34:	mullw   r9,r28,r9
   38:	subf    r8,r9,r8
   3c:	rotlwi  r8,r8,0
   40:	li      r8,66
   44:	ld      r27,-40(r1)
   48:	ld      r28,-32(r1)
   4c:	mr      r3,r8
   50:	blr

... and with constant blinding:
140 bytes emitted from JIT compiler (pass:3, flen:11)
d00000000bd6ab24 + <x>:
    0:	nop
    4:	nop
    8:	std     r27,-40(r1)
    c:	std     r28,-32(r1)
   10:	xor     r8,r8,r8
   14:	xor     r28,r28,r28
   18:	mr      r27,r3
   1c:	lis     r2,-22834
   20:	ori     r2,r2,36083
   24:	rotlwi  r2,r2,0
   28:	xori    r2,r2,36017
   2c:	xoris   r2,r2,42702
   30:	rotlwi  r2,r2,0
   34:	mr      r8,r2
   38:	rotlwi  r8,r8,0
   3c:	cmpwi   r28,0
   40:	bne     0x000000000000004c
   44:	li      r8,0
   48:	b       0x000000000000007c
   4c:	divwu   r9,r8,r28
   50:	mullw   r9,r28,r9
   54:	subf    r8,r9,r8
   58:	rotlwi  r8,r8,0
   5c:	lis     r2,-17137
   60:	ori     r2,r2,39065
   64:	rotlwi  r2,r2,0
   68:	xori    r2,r2,39131
   6c:	xoris   r2,r2,48399
   70:	rotlwi  r2,r2,0
   74:	mr      r8,r2
   78:	rotlwi  r8,r8,0
   7c:	ld      r27,-40(r1)
   80:	ld      r28,-32(r1)
   84:	mr      r3,r8
   88:	blr

Signed-off-by: Naveen N. Rao <redacted>

Acked-by: Daniel Borkmann <daniel@iogearbox.net>