From 7dcd11bfabdef7bcedded013e74a8f3d54010a9d Mon Sep 17 00:00:00 2001 From: Axel Heider Date: Thu, 25 Jan 2024 16:59:30 +0100 Subject: [PATCH] Section with Special Capabilities Signed-off-by: Axel Heider --- src/cap-description.adoc | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) diff --git a/src/cap-description.adoc b/src/cap-description.adoc index e6e22989..91e6a622 100644 --- a/src/cap-description.adoc +++ b/src/cap-description.adoc @@ -426,23 +426,21 @@ if ( (E < (CAP_MAX_E - 1)) & (t[XLENMAX: XLENMAX - 1] - b[XLENMAX - 1] > 1) ) That is, invert the most significant bit of _t_ if the decoded length of the capability is larger than E. -[#section_null_inf_cap] -=== NULL and Infinite Capabilities +[#section_special_caps] +=== Special Capabilities + +[#section_null_cap] +==== NULL Capability ifdef::cheri_v9_annotations[] NOTE: *CHERI v9 Note:* Encoding <> as zeros removes the need for the difference between in-memory and architectural format. endif::[] -The <> capability is represented with 0 in all fields. This implies -that <> has no permissions and its exponent E is CAP_MAX_E e.g. 52 -when XLENMAX=64, so its bounds cover the entire address space such that the -expanded base is 0 and top is 2^XLENMAX^. In contrast, the <> -capability grants all permissions while its bounds also cover the whole address -space. - -NOTE: The <> capability is also known as 'default', 'almighty', -or 'root' capability. +The <> capability is represented with 0 in all fields. This implies +that it has no permissions and its exponent E is CAP_MAX_E (52 for XLENMAX=64, +24 for XLENMAX=32), so its bounds cover the entire address space such that the +expanded base is 0 and top is 2^XLENMAX^. .Field values of the NULL capability [#null-cap,reftext="NULL",options=header,align=center,width="55%",cols="1,1,3"] @@ -461,6 +459,15 @@ or 'root' capability. | Reserved| zeros | All reserved fields |============================================================================== +[#section_infinite_cap] +==== Infinite Capability + +The <> capability grants all permissions while its bounds also +cover the whole address space. + +NOTE: The <> capability is also known as 'default', 'almighty', +or 'root' capability. + .Field values of the Infinite capability [#infinite-cap,reftext="Infinite"] [options=header,width="100%",align=center,width="55%",cols="1,1,3"]