diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-10-07 20:19:31 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-10-07 20:19:31 -0700 |
commit | 07021b43597f506cc525d139ed1a94e79cf184f2 (patch) | |
tree | 888ab33ec69b397ae6f8a2c82d14197047ee827e /Documentation/powerpc | |
parent | d1f5323370fceaed43a7ee38f4c7bfc7e70f28d0 (diff) | |
parent | b7b7013cac55d794940bd9cb7b7c55c9dececac4 (diff) | |
download | linux-07021b43597f506cc525d139ed1a94e79cf184f2.tar.gz |
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/powerpc')
-rw-r--r-- | Documentation/powerpc/syscall64-abi.txt | 105 |
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 index 000000000000..fa716a0d88bd --- /dev/null +++ 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. |