docs: speculation.txt: mark example blocks as such

Identify the example blocks there, in order to avoid Sphinx
warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mauro Carvalho Chehab 2019-04-10 06:56:27 -03:00 committed by Jonathan Corbet
parent 59bc64f0d0
commit 5d2a2c5910
1 changed files with 4 additions and 4 deletions

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@ -17,7 +17,7 @@ observed to extract secret information.
For example, in the presence of branch prediction, it is possible for bounds For example, in the presence of branch prediction, it is possible for bounds
checks to be ignored by code which is speculatively executed. Consider the checks to be ignored by code which is speculatively executed. Consider the
following code: following code::
int load_array(int *array, unsigned int index) int load_array(int *array, unsigned int index)
{ {
@ -27,7 +27,7 @@ following code:
return array[index]; return array[index];
} }
Which, on arm64, may be compiled to an assembly sequence such as: Which, on arm64, may be compiled to an assembly sequence such as::
CMP <index>, #MAX_ARRAY_ELEMS CMP <index>, #MAX_ARRAY_ELEMS
B.LT less B.LT less
@ -44,7 +44,7 @@ microarchitectural state which can be subsequently measured.
More complex sequences involving multiple dependent memory accesses may More complex sequences involving multiple dependent memory accesses may
result in sensitive information being leaked. Consider the following result in sensitive information being leaked. Consider the following
code, building on the prior example: code, building on the prior example::
int load_dependent_arrays(int *arr1, int *arr2, int index) int load_dependent_arrays(int *arr1, int *arr2, int index)
{ {
@ -77,7 +77,7 @@ A call to array_index_nospec(index, size) returns a sanitized index
value that is bounded to [0, size) even under cpu speculation value that is bounded to [0, size) even under cpu speculation
conditions. conditions.
This can be used to protect the earlier load_array() example: This can be used to protect the earlier load_array() example::
int load_array(int *array, unsigned int index) int load_array(int *array, unsigned int index)
{ {