docs: Update documentation to reflect what TAINT_CPU_OUT_OF_SPEC means

Here's a patch updating the meaning of TAINT_CPU_OUT_OF_SPEC after
Borislav introduced changes in a7e1f67ed29f and upcoming patches in tip.

TAINT_CPU_OUT_OF_SPEC now means a bit more what it implies as the
flag isn't set just because of a CPU misconfiguration or mismatch.
Historically it was for SMP kernel oops on an officially SMP incapable
processor but now it also covers CPUs whose MSRs have been incorrectly
poked at from userspace, drivers being used on non supported
architectures, broken firmware, mismatched CPUs, ...

Update documentation and script to reflect that.

Signed-off-by: Mathieu Chouquet-Stringer <me@mathieu.digital>
Link: https://lore.kernel.org/r/20201202153244.709752-1-me@mathieu.digital
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index d7a17859adbdc46cfd5df87b5820eb5398ed42e5..1d56a6b73a4e95ccb7c7b1798d7de41c231817f3 100644 (file)
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1336,7 +1336,7 @@ ORed together. The letters are seen in "Tainted" line of Oops reports.
 ======  =====  ==============================================================
      1  `(P)`  proprietary module was loaded
      2  `(F)`  module was force loaded
-     4  `(S)`  SMP kernel oops on an officially SMP incapable processor
+     4  `(S)`  kernel running on an out of specification system
      8  `(R)`  module was force unloaded
     16  `(M)`  processor reported a Machine Check Exception (MCE)
     32  `(B)`  bad page referenced or some unexpected page flags

diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst
index f718a2eaf1f614685c7bb14115fbac2d416697cd..ceeed7b0798da68239854044fb6f0551af4b382b 100644 (file)
--- a/Documentation/admin-guide/tainted-kernels.rst
+++ b/Documentation/admin-guide/tainted-kernels.rst
@@ -84,7 +84,7 @@ Bit  Log  Number  Reason that got the kernel tainted
 ===  ===  ======  ========================================================
   0  G/P       1  proprietary module was loaded
   1  _/F       2  module was force loaded
-  2  _/S       4  SMP kernel oops on an officially SMP incapable processor
+  2  _/S       4  kernel running on an out of specification system
   3  _/R       8  module was force unloaded
   4  _/M      16  processor reported a Machine Check Exception (MCE)
   5  _/B      32  bad page referenced or some unexpected page flags
@@ -116,10 +116,23 @@ More detailed explanation for tainting
  1)  ``F`` if any module was force loaded by ``insmod -f``, ``' '`` if all
      modules were loaded normally.
 
- 2)  ``S`` if the oops occurred on an SMP kernel running on hardware that
-     hasn't been certified as safe to run multiprocessor.
-     Currently this occurs only on various Athlons that are not
-     SMP capable.
+ 2)  ``S`` if the kernel is running on a processor or system that is out of
+     specification: hardware has been put into an unsupported configuration,
+     therefore proper execution cannot be guaranteed.
+     Kernel will be tainted if, for example:
+
+     - on x86: PAE is forced through forcepae on intel CPUs (such as Pentium M)
+       which do not report PAE but may have a functional implementation, an SMP
+       kernel is running on non officially capable SMP Athlon CPUs, MSRs are
+       being poked at from userspace.
+     - on arm: kernel running on certain CPUs (such as Keystone 2) without
+       having certain kernel features enabled.
+     - on arm64: there are mismatched hardware features between CPUs, the
+       bootloader has booted CPUs in different modes.
+     - certain drivers are being used on non supported architectures (such as
+       scsi/snic on something else than x86_64, scsi/ips on non
+       x86/x86_64/itanium, have broken firmware settings for the
+       irqchip/irq-gic on arm64 ...).
 
  3)  ``R`` if a module was force unloaded by ``rmmod -f``, ``' '`` if all
      modules were unloaded normally.

diff --git a/tools/debugging/kernel-chktaint b/tools/debugging/kernel-chktaint
index 2240cb56e6e5e6ed30a75913d4d5fecbb8f193c3..607b2b280945bc4de744bf70e90fba6f70cafa8d 100755 (executable)
--- a/tools/debugging/kernel-chktaint
+++ b/tools/debugging/kernel-chktaint
@@ -72,7 +72,7 @@ if [ `expr $T % 2` -eq 0 ]; then
        addout " "
 else
        addout "S"
-       echo " * SMP kernel oops on an officially SMP incapable processor (#2)"
+       echo " * kernel running on an out of specification system (#2)"
 fi
 
 T=`expr $T / 2`