If we then OR this with 0x40, then the value of 6th bit (0th is first bit) become known, so the right mask is 0xbf instead of 0xcf.
Signed-off-by: Wang YanQing <udkni...@gmail.com> --- Documentation/networking/filter.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt index 8781485..a4508ec 100644 --- a/Documentation/networking/filter.txt +++ b/Documentation/networking/filter.txt @@ -1134,7 +1134,7 @@ The verifier's knowledge about the variable offset consists of: mask and value; no bit should ever be 1 in both. For example, if a byte is read into a register from memory, the register's top 56 bits are known zero, while the low 8 are unknown - which is represented as the tnum (0x0; 0xff). If we -then OR this with 0x40, we get (0x40; 0xcf), then if we add 1 we get (0x0; +then OR this with 0x40, we get (0x40; 0xbf), then if we add 1 we get (0x0; 0x1ff), because of potential carries. Besides arithmetic, the register state can also be updated by conditional branches. For instance, if a SCALAR_VALUE is compared > 8, in the 'true' branch -- 1.8.5.6.2.g3d8a54e.dirty
