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authorLinus Torvalds <torvalds@linux-foundation.org>2016-10-08 06:19:31 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-08 06:19:31 +0300
commit07021b43597f506cc525d139ed1a94e79cf184f2 (patch)
tree888ab33ec69b397ae6f8a2c82d14197047ee827e /Documentation
parentd1f5323370fceaed43a7ee38f4c7bfc7e70f28d0 (diff)
parentb7b7013cac55d794940bd9cb7b7c55c9dececac4 (diff)
downloadlinux-07021b43597f506cc525d139ed1a94e79cf184f2.tar.xz
Merge tag 'powerpc-4.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman: "Highlights: - Major rework of Book3S 64-bit exception vectors (Nicholas Piggin) - Use gas sections for arranging exception vectors et. al. - Large set of TM cleanups and selftests (Cyril Bur) - Enable transactional memory (TM) lazily for userspace (Cyril Bur) - Support for XZ compression in the zImage wrapper (Oliver O'Halloran) - Add support for bpf constant blinding (Naveen N. Rao) - Beginnings of upstream support for PA Semi Nemo motherboards (Darren Stevens) Fixes: - Ensure .mem(init|exit).text are within _stext/_etext (Michael Ellerman) - xmon: Don't use ld on 32-bit (Michael Ellerman) - vdso64: Use double word compare on pointers (Anton Blanchard) - powerpc/nvram: Fix an incorrect partition merge (Pan Xinhui) - powerpc: Fix usage of _PAGE_RO in hugepage (Christophe Leroy) - powerpc/mm: Update FORCE_MAX_ZONEORDER range to allow hugetlb w/4K (Aneesh Kumar K.V) - Fix memory leak in queue_hotplug_event() error path (Andrew Donnellan) - Replay hypervisor maintenance interrupt first (Nicholas Piggin) Various performance optimisations (Anton Blanchard): - Align hot loops of memset() and backwards_memcpy() - During context switch, check before setting mm_cpumask - Remove static branch prediction in atomic{, 64}_add_unless - Only disable HAVE_EFFICIENT_UNALIGNED_ACCESS on POWER7 little endian - Set default CPU type to POWER8 for little endian builds Cleanups & features: - Sparse fixes/cleanups (Daniel Axtens) - Preserve CFAR value on SLB miss caused by access to bogus address (Paul Mackerras) - Radix MMU fixups for POWER9 (Aneesh Kumar K.V) - Support for setting used_(vsr|vr|spe) in sigreturn path (for CRIU) (Simon Guo) - Optimise syscall entry for virtual, relocatable case (Nicholas Piggin) - Optimise MSR handling in exception handling (Nicholas Piggin) - Support for kexec with Radix MMU (Benjamin Herrenschmidt) - powernv EEH fixes (Russell Currey) - Suprise PCI hotplug support for powernv (Gavin Shan) - Endian/sparse fixes for powernv PCI (Gavin Shan) - Defconfig updates (Anton Blanchard) - KVM: PPC: Book3S HV: Migrate pinned pages out of CMA (Balbir Singh) - cxl: Flush PSL cache before resetting the adapter (Frederic Barrat) - cxl: replace loop with for_each_child_of_node(), remove unneeded of_node_put() (Andrew Donnellan) - Fix HV facility unavailable to use correct handler (Nicholas Piggin) - Remove unnecessary syscall trampoline (Nicholas Piggin) - fadump: Fix build break when CONFIG_PROC_VMCORE=n (Michael Ellerman) - Quieten EEH message when no adapters are found (Anton Blanchard) - powernv: Add PHB register dump debugfs handle (Russell Currey) - Use kprobe blacklist for exception handlers & asm functions (Nicholas Piggin) - Document the syscall ABI (Nicholas Piggin) - MAINTAINERS: Update cxl maintainers (Michael Neuling) - powerpc: Remove all usages of NO_IRQ (Michael Ellerman) Minor cleanups: - Andrew Donnellan, Christophe Leroy, Colin Ian King, Cyril Bur, Frederic Barrat, Pan Xinhui, PrasannaKumar Muralidharan, Rui Teng, Simon Guo" * tag 'powerpc-4.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (156 commits) powerpc/bpf: Add support for bpf constant blinding powerpc/bpf: Implement support for tail calls powerpc/bpf: Introduce accessors for using the tmp local stack space powerpc/fadump: Fix build break when CONFIG_PROC_VMCORE=n powerpc: tm: Enable transactional memory (TM) lazily for userspace powerpc/tm: Add TM Unavailable Exception powerpc: Remove do_load_up_transact_{fpu,altivec} powerpc: tm: Rename transct_(*) to ck(\1)_state powerpc: tm: Always use fp_state and vr_state to store live registers selftests/powerpc: Add checks for transactional VSXs in signal contexts selftests/powerpc: Add checks for transactional VMXs in signal contexts selftests/powerpc: Add checks for transactional FPUs in signal contexts selftests/powerpc: Add checks for transactional GPRs in signal contexts selftests/powerpc: Check that signals always get delivered selftests/powerpc: Add TM tcheck helpers in C selftests/powerpc: Allow tests to extend their kill timeout selftests/powerpc: Introduce GPR asm helper header file selftests/powerpc: Move VMX stack frame macros to header file selftests/powerpc: Rework FPU stack placement macros and move to header file selftests/powerpc: Check for VSX preservation across userspace preemption ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/powerpc/syscall64-abi.txt105
1 files changed, 105 insertions, 0 deletions
diff --git a/Documentation/powerpc/syscall64-abi.txt b/Documentation/powerpc/syscall64-abi.txt
new file mode 100644
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+++ b/Documentation/powerpc/syscall64-abi.txt
@@ -0,0 +1,105 @@
+===============================================
+Power Architecture 64-bit Linux system call ABI
+===============================================
+
+syscall
+=======
+
+syscall calling sequence[*] matches the Power Architecture 64-bit ELF ABI
+specification C function calling sequence, including register preservation
+rules, with the following differences.
+
+[*] Some syscalls (typically low-level management functions) may have
+ different calling sequences (e.g., rt_sigreturn).
+
+Parameters and return value
+---------------------------
+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.
+
+Stack
+-----
+System calls do not modify the caller's stack frame. For example, the caller's
+stack frame LR and CR save fields are not used.
+
+Register preservation rules
+---------------------------
+Register preservation rules match the ELF ABI calling sequence with the
+following differences:
+
+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)
+cr1, cr5-7: Nonvolatile.
+lr: Nonvolatile.
+
+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
+transaction state, and the syscall can affect the behavior of the transaction.
+
+If the processor is in suspended state when a syscall is made, the syscall
+will be performed as normal, and will return as normal. The syscall will be
+performed in suspended state, so its side effects will be persistent according
+to the usual transactional memory semantics. A syscall may or may not result
+in the transaction being doomed by hardware.
+
+If the processor is in transactional state when a syscall is made, then the
+behavior depends on the presence of PPC_FEATURE2_HTM_NOSC in the AT_HWCAP2 ELF
+auxiliary vector.
+
+- If present, which is the case for newer kernels, then the syscall will not
+ be performed and the transaction will be doomed by the kernel with the
+ failure code TM_CAUSE_SYSCALL | TM_CAUSE_PERSISTENT in the TEXASR SPR.
+
+- If not present (older kernels), then the kernel will suspend the
+ transactional state and the syscall will proceed as in the case of a
+ suspended state syscall, and will resume the transactional state before
+ returning to the caller. This case is not well defined or supported, so this
+ behavior should not be relied upon.
+
+
+vsyscall
+========
+
+vsyscall calling sequence matches the syscall calling sequence, with the
+following differences. Some vsyscalls may have different calling sequences.
+
+Parameters and return value
+---------------------------
+r0 is not used as an input. The vsyscall is selected by its address.
+
+Stack
+-----
+The vsyscall may or may not use the caller's stack frame save areas.
+
+Register preservation rules
+---------------------------
+r0: Volatile.
+cr1, cr5-7: Volatile.
+lr: Volatile.
+
+Invocation
+----------
+The vsyscall is performed with a branch-with-link instruction to the vsyscall
+function address.
+
+Transactional Memory
+--------------------
+vsyscalls will run in the same transactional state as the caller. A vsyscall
+may or may not result in the transaction being doomed by hardware.