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-rw-r--r--Documentation/devicetree/bindings/dma/snps-dma.txt2
-rw-r--r--Documentation/devicetree/bindings/pinctrl/pinctrl-palmas.txt9
-rw-r--r--Documentation/filesystems/ext4.txt2
-rw-r--r--Documentation/kernel-parameters.txt2
-rw-r--r--Documentation/speculation.txt90
5 files changed, 101 insertions, 4 deletions
diff --git a/Documentation/devicetree/bindings/dma/snps-dma.txt b/Documentation/devicetree/bindings/dma/snps-dma.txt
index c261598164a7..17d43ca27f41 100644
--- a/Documentation/devicetree/bindings/dma/snps-dma.txt
+++ b/Documentation/devicetree/bindings/dma/snps-dma.txt
@@ -58,6 +58,6 @@ Example:
interrupts = <0 35 0x4>;
status = "disabled";
dmas = <&dmahost 12 0 1>,
- <&dmahost 13 0 1 0>;
+ <&dmahost 13 1 0>;
dma-names = "rx", "rx";
};
diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-palmas.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-palmas.txt
index caf297bee1fb..c28d4eb83b76 100644
--- a/Documentation/devicetree/bindings/pinctrl/pinctrl-palmas.txt
+++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-palmas.txt
@@ -35,6 +35,15 @@ Optional properties:
- ti,palmas-enable-dvfs2: Enable DVFS2. Configure pins for DVFS2 mode.
Selection primary or secondary function associated to GPADC_START
and SYSEN2 pin/pad for DVFS2 interface
+- ti,palmas-override-powerhold: This is applicable for PMICs for which
+ GPIO7 is configured in POWERHOLD mode which has higher priority
+ over DEV_ON bit and keeps the PMIC supplies on even after the DEV_ON
+ bit is turned off. This property enables driver to over ride the
+ POWERHOLD value to GPIO7 so as to turn off the PMIC in power off
+ scenarios. So for GPIO7 if ti,palmas-override-powerhold is set
+ then the GPIO_7 field should never be muxed to anything else.
+ It should be set to POWERHOLD by default and only in case of
+ power off scenarios the driver will over ride the mux value.
This binding uses the following generic properties as defined in
pinctrl-bindings.txt:
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 6c0108eb0137..2139ea253142 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -233,7 +233,7 @@ data_err=ignore(*) Just print an error message if an error occurs
data_err=abort Abort the journal if an error occurs in a file
data buffer in ordered mode.
-grpid Give objects the same group ID as their creator.
+grpid New objects have the group ID of their parent.
bsdgroups
nogrpid (*) New objects have the group ID of their creator.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9a415fed5ac7..a5a963b86748 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2484,8 +2484,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
norandmaps Don't use address space randomization. Equivalent to
echo 0 > /proc/sys/kernel/randomize_va_space
- noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
-
noreplace-smp [X86-32,SMP] Don't replace SMP instructions
with UP alternatives
diff --git a/Documentation/speculation.txt b/Documentation/speculation.txt
new file mode 100644
index 000000000000..e9e6cbae2841
--- /dev/null
+++ b/Documentation/speculation.txt
@@ -0,0 +1,90 @@
+This document explains potential effects of speculation, and how undesirable
+effects can be mitigated portably using common APIs.
+
+===========
+Speculation
+===========
+
+To improve performance and minimize average latencies, many contemporary CPUs
+employ speculative execution techniques such as branch prediction, performing
+work which may be discarded at a later stage.
+
+Typically speculative execution cannot be observed from architectural state,
+such as the contents of registers. However, in some cases it is possible to
+observe its impact on microarchitectural state, such as the presence or
+absence of data in caches. Such state may form side-channels which can be
+observed to extract secret information.
+
+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
+following code:
+
+ int load_array(int *array, unsigned int index)
+ {
+ if (index >= MAX_ARRAY_ELEMS)
+ return 0;
+ else
+ return array[index];
+ }
+
+Which, on arm64, may be compiled to an assembly sequence such as:
+
+ CMP <index>, #MAX_ARRAY_ELEMS
+ B.LT less
+ MOV <returnval>, #0
+ RET
+ less:
+ LDR <returnval>, [<array>, <index>]
+ RET
+
+It is possible that a CPU mis-predicts the conditional branch, and
+speculatively loads array[index], even if index >= MAX_ARRAY_ELEMS. This
+value will subsequently be discarded, but the speculated load may affect
+microarchitectural state which can be subsequently measured.
+
+More complex sequences involving multiple dependent memory accesses may
+result in sensitive information being leaked. Consider the following
+code, building on the prior example:
+
+ int load_dependent_arrays(int *arr1, int *arr2, int index)
+ {
+ int val1, val2,
+
+ val1 = load_array(arr1, index);
+ val2 = load_array(arr2, val1);
+
+ return val2;
+ }
+
+Under speculation, the first call to load_array() may return the value
+of an out-of-bounds address, while the second call will influence
+microarchitectural state dependent on this value. This may provide an
+arbitrary read primitive.
+
+====================================
+Mitigating speculation side-channels
+====================================
+
+The kernel provides a generic API to ensure that bounds checks are
+respected even under speculation. Architectures which are affected by
+speculation-based side-channels are expected to implement these
+primitives.
+
+The array_index_nospec() helper in <linux/nospec.h> can be used to
+prevent information from being leaked via side-channels.
+
+A call to array_index_nospec(index, size) returns a sanitized index
+value that is bounded to [0, size) even under cpu speculation
+conditions.
+
+This can be used to protect the earlier load_array() example:
+
+ int load_array(int *array, unsigned int index)
+ {
+ if (index >= MAX_ARRAY_ELEMS)
+ return 0;
+ else {
+ index = array_index_nospec(index, MAX_ARRAY_ELEMS);
+ return array[index];
+ }
+ }