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authorLinus Torvalds <torvalds@linux-foundation.org>2020-08-07 10:33:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-07 10:33:50 -0700
commit25d8d4eecace9de5a6a2193e4df1917afbdd3052 (patch)
tree1f1bbde6423745251c41fb4d1842e70b9f7bca07 /Documentation/powerpc
parent60e76bb8a4e4c5398ea9053535e1fd0c9d6bb06e (diff)
parenta7aaa2f26bfd932a654706b19859e7adf802bee2 (diff)
downloadlwn-25d8d4eecace9de5a6a2193e4df1917afbdd3052.tar.gz
lwn-25d8d4eecace9de5a6a2193e4df1917afbdd3052.zip
Merge tag 'powerpc-5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman: - Add support for (optionally) using queued spinlocks & rwlocks. - Support for a new faster system call ABI using the scv instruction on Power9 or later. - Drop support for the PROT_SAO mmap/mprotect flag as it will be unsupported on Power10 and future processors, leaving us with no way to implement the functionality it requests. This risks breaking userspace, though we believe it is unused in practice. - A bug fix for, and then the removal of, our custom stack expansion checking. We now allow stack expansion up to the rlimit, like other architectures. - Remove the remnants of our (previously disabled) topology update code, which tried to react to NUMA layout changes on virtualised systems, but was prone to crashes and other problems. - Add PMU support for Power10 CPUs. - A change to our signal trampoline so that we don't unbalance the link stack (branch return predictor) in the signal delivery path. - Lots of other cleanups, refactorings, smaller features and so on as usual. Thanks to: Abhishek Goel, Alastair D'Silva, Alexander A. Klimov, Alexey Kardashevskiy, Alistair Popple, Andrew Donnellan, Aneesh Kumar K.V, Anju T Sudhakar, Anton Blanchard, Arnd Bergmann, Athira Rajeev, Balamuruhan S, Bharata B Rao, Bill Wendling, Bin Meng, Cédric Le Goater, Chris Packham, Christophe Leroy, Christoph Hellwig, Daniel Axtens, Dan Williams, David Lamparter, Desnes A. Nunes do Rosario, Erhard F., Finn Thain, Frederic Barrat, Ganesh Goudar, Gautham R. Shenoy, Geoff Levand, Greg Kurz, Gustavo A. R. Silva, Hari Bathini, Harish, Imre Kaloz, Joel Stanley, Joe Perches, John Crispin, Jordan Niethe, Kajol Jain, Kamalesh Babulal, Kees Cook, Laurent Dufour, Leonardo Bras, Li RongQing, Madhavan Srinivasan, Mahesh Salgaonkar, Mark Cave-Ayland, Michal Suchanek, Milton Miller, Mimi Zohar, Murilo Opsfelder Araujo, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nayna Jain, Nicholas Piggin, Oliver O'Halloran, Palmer Dabbelt, Pedro Miraglia Franco de Carvalho, Philippe Bergheaud, Pingfan Liu, Pratik Rajesh Sampat, Qian Cai, Qinglang Miao, Randy Dunlap, Ravi Bangoria, Sachin Sant, Sam Bobroff, Sandipan Das, Santosh Sivaraj, Satheesh Rajendran, Shirisha Ganta, Sourabh Jain, Srikar Dronamraju, Stan Johnson, Stephen Rothwell, Thadeu Lima de Souza Cascardo, Thiago Jung Bauermann, Tom Lane, Vaibhav Jain, Vladis Dronov, Wei Yongjun, Wen Xiong, YueHaibing. * tag 'powerpc-5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (337 commits) selftests/powerpc: Fix pkey syscall redefinitions powerpc: Fix circular dependency between percpu.h and mmu.h powerpc/powernv/sriov: Fix use of uninitialised variable selftests/powerpc: Skip vmx/vsx/tar/etc tests on older CPUs powerpc/40x: Fix assembler warning about r0 powerpc/papr_scm: Add support for fetching nvdimm 'fuel-gauge' metric powerpc/papr_scm: Fetch nvdimm performance stats from PHYP cpuidle: pseries: Fixup exit latency for CEDE(0) cpuidle: pseries: Add function to parse extended CEDE records cpuidle: pseries: Set the latency-hint before entering CEDE selftests/powerpc: Fix online CPU selection powerpc/perf: Consolidate perf_callchain_user_[64|32]() powerpc/pseries/hotplug-cpu: Remove double free in error path powerpc/pseries/mobility: Add pr_debug() for device tree changes powerpc/pseries/mobility: Set pr_fmt() powerpc/cacheinfo: Warn if cache object chain becomes unordered powerpc/cacheinfo: Improve diagnostics about malformed cache lists powerpc/cacheinfo: Use name@unit instead of full DT path in debug messages powerpc/cacheinfo: Set pr_fmt() powerpc: fix function annotations to avoid section mismatch warnings with gcc-10 ...
Diffstat (limited to 'Documentation/powerpc')
-rw-r--r--Documentation/powerpc/cpu_families.rst10
-rw-r--r--Documentation/powerpc/mpc52xx.rst2
-rw-r--r--Documentation/powerpc/syscall64-abi.rst42
3 files changed, 37 insertions, 17 deletions
diff --git a/Documentation/powerpc/cpu_families.rst b/Documentation/powerpc/cpu_families.rst
index 1e063c5440c3..9b84e045e713 100644
--- a/Documentation/powerpc/cpu_families.rst
+++ b/Documentation/powerpc/cpu_families.rst
@@ -9,7 +9,9 @@ and are supported by arch/powerpc.
Book3S (aka sPAPR)
------------------
-- Hash MMU
+- Hash MMU (except 603 and e300)
+- Software loaded TLB (603 and e300)
+- Selectable Software loaded TLB in addition to hash MMU (755, 7450, e600)
- Mix of 32 & 64 bit::
+--------------+ +----------------+
@@ -24,9 +26,9 @@ Book3S (aka sPAPR)
| |
| |
v v
- +--------------+ +----------------+ +-------+
- | 604 | | 750 (G3) | ---> | 750CX |
- +--------------+ +----------------+ +-------+
+ +--------------+ +-----+ +----------------+ +-------+
+ | 604 | | 755 | <--- | 750 (G3) | ---> | 750CX |
+ +--------------+ +-----+ +----------------+ +-------+
| | |
| | |
v v v
diff --git a/Documentation/powerpc/mpc52xx.rst b/Documentation/powerpc/mpc52xx.rst
index 8676ac63e077..30260707c3fe 100644
--- a/Documentation/powerpc/mpc52xx.rst
+++ b/Documentation/powerpc/mpc52xx.rst
@@ -2,7 +2,7 @@
Linux 2.6.x on MPC52xx family
=============================
-For the latest info, go to http://www.246tNt.com/mpc52xx/
+For the latest info, go to https://www.246tNt.com/mpc52xx/
To compile/use :
diff --git a/Documentation/powerpc/syscall64-abi.rst b/Documentation/powerpc/syscall64-abi.rst
index e49f69f941b9..46caaadbb029 100644
--- a/Documentation/powerpc/syscall64-abi.rst
+++ b/Documentation/powerpc/syscall64-abi.rst
@@ -5,6 +5,15 @@ Power Architecture 64-bit Linux system call ABI
syscall
=======
+Invocation
+----------
+The syscall is made with the sc instruction, and returns with execution
+continuing at the instruction following the sc instruction.
+
+If PPC_FEATURE2_SCV appears in the AT_HWCAP2 ELF auxiliary vector, the
+scv 0 instruction is an alternative that may provide better performance,
+with some differences to calling sequence.
+
syscall calling sequence\ [1]_ matches the Power Architecture 64-bit ELF ABI
specification C function calling sequence, including register preservation
rules, with the following differences.
@@ -12,16 +21,23 @@ rules, with the following differences.
.. [1] Some syscalls (typically low-level management functions) may have
different calling sequences (e.g., rt_sigreturn).
-Parameters and return value
----------------------------
+Parameters
+----------
The system call number is specified in r0.
There is a maximum of 6 integer parameters to a syscall, passed in r3-r8.
-Both a return value and a return error code are returned. cr0.SO is the return
-error code, and r3 is the return value or error code. When cr0.SO is clear,
-the syscall succeeded and r3 is the return value. When cr0.SO is set, the
-syscall failed and r3 is the error code that generally corresponds to errno.
+Return value
+------------
+- For the sc instruction, both a value and an error condition are returned.
+ cr0.SO is the error condition, and r3 is the return value. When cr0.SO is
+ clear, the syscall succeeded and r3 is the return value. When cr0.SO is set,
+ the syscall failed and r3 is the error value (that normally corresponds to
+ errno).
+
+- For the scv 0 instruction, the return value indicates failure if it is
+ -4095..-1 (i.e., it is >= -MAX_ERRNO (-4095) as an unsigned comparison),
+ in which case the error value is the negated return value.
Stack
-----
@@ -34,22 +50,23 @@ Register preservation rules match the ELF ABI calling sequence with the
following differences:
=========== ============= ========================================
+--- For the sc instruction, differences with the ELF ABI ---
r0 Volatile (System call number.)
r3 Volatile (Parameter 1, and return value.)
r4-r8 Volatile (Parameters 2-6.)
-cr0 Volatile (cr0.SO is the return error condition)
+cr0 Volatile (cr0.SO is the return error condition.)
cr1, cr5-7 Nonvolatile
lr Nonvolatile
+
+--- For the scv 0 instruction, differences with the ELF ABI ---
+r0 Volatile (System call number.)
+r3 Volatile (Parameter 1, and return value.)
+r4-r8 Volatile (Parameters 2-6.)
=========== ============= ========================================
All floating point and vector data registers as well as control and status
registers are nonvolatile.
-Invocation
-----------
-The syscall is performed with the sc instruction, and returns with execution
-continuing at the instruction following the sc instruction.
-
Transactional Memory
--------------------
Syscall behavior can change if the processor is in transactional or suspended
@@ -75,6 +92,7 @@ auxiliary vector.
returning to the caller. This case is not well defined or supported, so this
behavior should not be relied upon.
+scv 0 syscalls will always behave as PPC_FEATURE2_HTM_NOSC.
vsyscall
========