diff options
Diffstat (limited to 'Documentation/x86')
| -rw-r--r-- | Documentation/x86/intel_mpx.txt | 10 | ||||
| -rw-r--r-- | Documentation/x86/pat.txt | 32 | ||||
| -rw-r--r-- | Documentation/x86/tlb.txt | 4 | ||||
| -rw-r--r-- | Documentation/x86/x86_64/machinecheck | 2 |
4 files changed, 40 insertions, 8 deletions
diff --git a/Documentation/x86/intel_mpx.txt b/Documentation/x86/intel_mpx.txt index 818518a3f..85d0549ad 100644 --- a/Documentation/x86/intel_mpx.txt +++ b/Documentation/x86/intel_mpx.txt @@ -45,7 +45,7 @@ is how we expect the compiler, application and kernel to work together. MPX-instrumented. 3) The kernel detects that the CPU has MPX, allows the new prctl() to succeed, and notes the location of the bounds directory. Userspace is - expected to keep the bounds directory at that locationWe note it + expected to keep the bounds directory at that location. We note it instead of reading it each time because the 'xsave' operation needed to access the bounds directory register is an expensive operation. 4) If the application needs to spill bounds out of the 4 registers, it @@ -136,7 +136,7 @@ A: MPX-enabled application will possibly create a lot of bounds tables in If we were to preallocate them for the 128TB of user virtual address space, we would need to reserve 512TB+2GB, which is larger than the entire virtual address space today. This means they can not be reserved - ahead of time. Also, a single process's pre-popualated bounds directory + ahead of time. Also, a single process's pre-populated bounds directory consumes 2GB of virtual *AND* physical memory. IOW, it's completely infeasible to prepopulate bounds directories. @@ -151,7 +151,7 @@ A: This would work if we could hook the site of each and every memory these calls. Q: Could a bounds fault be handed to userspace and the tables allocated - there in a signal handler intead of in the kernel? + there in a signal handler instead of in the kernel? A: mmap() is not on the list of safe async handler functions and even if mmap() would work it still requires locking or nasty tricks to keep track of the allocation state there. @@ -167,7 +167,7 @@ If a #BR is generated due to a bounds violation caused by MPX. We need to decode MPX instructions to get violation address and set this address into extended struct siginfo. -The _sigfault feild of struct siginfo is extended as follow: +The _sigfault field of struct siginfo is extended as follow: 87 /* SIGILL, SIGFPE, SIGSEGV, SIGBUS */ 88 struct { @@ -240,5 +240,5 @@ them at the same bounds table. This is allowed architecturally. See more information "Intel(R) Architecture Instruction Set Extensions Programming Reference" (9.3.4). -However, if users did this, the kernel might be fooled in to unmaping an +However, if users did this, the kernel might be fooled in to unmapping an in-use bounds table since it does not recognize sharing. diff --git a/Documentation/x86/pat.txt b/Documentation/x86/pat.txt index 54944c71b..2a4ee6302 100644 --- a/Documentation/x86/pat.txt +++ b/Documentation/x86/pat.txt @@ -196,3 +196,35 @@ Another, more verbose way of getting PAT related debug messages is with "debugpat" boot parameter. With this parameter, various debug messages are printed to dmesg log. +PAT Initialization +------------------ + +The following table describes how PAT is initialized under various +configurations. The PAT MSR must be updated by Linux in order to support WC +and WT attributes. Otherwise, the PAT MSR has the value programmed in it +by the firmware. Note, Xen enables WC attribute in the PAT MSR for guests. + + MTRR PAT Call Sequence PAT State PAT MSR + ========================================================= + E E MTRR -> PAT init Enabled OS + E D MTRR -> PAT init Disabled - + D E MTRR -> PAT disable Disabled BIOS + D D MTRR -> PAT disable Disabled - + - np/E PAT -> PAT disable Disabled BIOS + - np/D PAT -> PAT disable Disabled - + E !P/E MTRR -> PAT init Disabled BIOS + D !P/E MTRR -> PAT disable Disabled BIOS + !M !P/E MTRR stub -> PAT disable Disabled BIOS + + Legend + ------------------------------------------------ + E Feature enabled in CPU + D Feature disabled/unsupported in CPU + np "nopat" boot option specified + !P CONFIG_X86_PAT option unset + !M CONFIG_MTRR option unset + Enabled PAT state set to enabled + Disabled PAT state set to disabled + OS PAT initializes PAT MSR with OS setting + BIOS PAT keeps PAT MSR with BIOS setting + diff --git a/Documentation/x86/tlb.txt b/Documentation/x86/tlb.txt index 39d172326..6a0607b99 100644 --- a/Documentation/x86/tlb.txt +++ b/Documentation/x86/tlb.txt @@ -5,7 +5,7 @@ memory, it has two choices: from areas other than the one we are trying to flush will be destroyed and must be refilled later, at some cost. 2. Use the invlpg instruction to invalidate a single page at a - time. This could potentialy cost many more instructions, but + time. This could potentially cost many more instructions, but it is a much more precise operation, causing no collateral damage to other TLB entries. @@ -19,7 +19,7 @@ Which method to do depends on a few things: work. 3. The size of the TLB. The larger the TLB, the more collateral damage we do with a full flush. So, the larger the TLB, the - more attrative an individual flush looks. Data and + more attractive an individual flush looks. Data and instructions have separate TLBs, as do different page sizes. 4. The microarchitecture. The TLB has become a multi-level cache on modern CPUs, and the global flushes have become more diff --git a/Documentation/x86/x86_64/machinecheck b/Documentation/x86/x86_64/machinecheck index b1fb30273..d0648a74f 100644 --- a/Documentation/x86/x86_64/machinecheck +++ b/Documentation/x86/x86_64/machinecheck @@ -36,7 +36,7 @@ between all CPUs. check_interval How often to poll for corrected machine check errors, in seconds - (Note output is hexademical). Default 5 minutes. When the poller + (Note output is hexadecimal). Default 5 minutes. When the poller finds MCEs it triggers an exponential speedup (poll more often) on the polling interval. When the poller stops finding MCEs, it triggers an exponential backoff (poll less often) on the polling |