path: root/src/thread/sh
AgeCommit message (Collapse)AuthorLines
2018-09-12use hidden visibility for sh __unmapself backendsRich Felker-2/+3
2018-09-12make arch __clone backends hiddenRich Felker-0/+1
these are not a public interface and are not intended to be callable from anywhere but the public clone function or other places in libc.
2018-09-05define and use internal macros for hidden visibility, weak refsRich Felker-7/+4
this cleans up what had become widespread direct inline use of "GNU C" style attributes directly in the source, and lowers the barrier to increased use of hidden visibility, which will be useful to recovering some of the efficiency lost when the protected visibility hack was dropped in commit dc2f368e565c37728b0d620380b849c3a1ddd78f, especially on archs where the PLT ABI is costly.
2017-06-08use hard-coded sh4a atomic opcodes to avoid linker errors on shRich Felker-4/+4
when using the sh4a opcodes, the assembler tags the resulting object file as requiring sh4a. the linker then refuses to (static) link it with object files marked as requiring j2, since there is no isa level that includes both sh4a and j2 instructions.
2016-01-22move sh __unmapself code from arch/sh/src to main src treeRich Felker-0/+24
2016-01-21overhaul sh atomics for new atomics framework, add j-core cas.l backendRich Felker-0/+105
sh needs runtime-selected atomic backends since there are a number of supported models that use non-forwards-compatible (non-smp-compatible) atomic mechanisms. previously, the code paths for this were highly inefficient since they involved C function calls with multiple branches in the callee and heavy spills in the caller. the new code performs calls the runtime-selected asm fragment from inline asm with extremely minimal clobbers, rather than using a function call. for the sh4a case where the atomic mechanism is known and there is no forward-compatibility issue, the movli.l and movco.l instructions are provided as a_ll and a_sc, allowing the new shared atomic.h to generate efficient inline versions of all the basic atomic operations without needing a cas loop.
2015-11-02use explicit __cp_cancel label in cancellable syscall asm for all archsRich Felker-11/+11
previously, only archs that needed to do stack cleanup defined a __cp_cancel label for acting on cancellation in their syscall asm, and a default definition was provided by a weak alias to __cancel, the C function. this resulted in wrong codegen for arm on gcc versions affected by pr 68178 and possibly similar issues (like pr 66609) on other archs, and also created an inconsistency where the __cp_begin and __cp_end labels were treated as const data but __cp_cancel was treated as a function. this in turn caused incorrect code generation on archs where function pointers point to function descriptors rather than code (for now, only sh/fdpic).
2015-09-12make sh clone asm fdpic-compatibleRich Felker-3/+9
clone calls back to a function pointer provided by the caller, which will actually be a pointer to a function descriptor on fdpic. the obvious solution is to have a separate version of clone for fdpic, but I have taken a simpler approach to go around the problem. instead of calling the pointed-to function from asm, a direct call is made to an internal C function which then calls the pointed-to function. this lets the C compiler generate the appropriate calling convention for an indirect call with no need for ABI-specific assembly.
2015-06-16switch to using trap number 31 for syscalls on shRich Felker-5/+5
nominally the low bits of the trap number on sh are the number of syscall arguments, but they have never been used by the kernel, and some code making syscalls does not even know the number of arguments and needs to pass an arbitrary high number anyway. sh3/sh4 traditionally used the trap range 16-31 for syscalls, but part of this range overlapped with hardware exceptions/interrupts on sh2 hardware, so an incompatible range 32-47 was chosen for sh2. using trap number 31 everywhere, since it's in the existing sh3/sh4 range and does not conflict with sh2 hardware, is a proposed unification of the kernel syscall convention that will allow binaries to be shared between sh2 and sh3/sh4. if this is not accepted into the kernel, we can refit the sh2 target with runtime selection mechanisms for the trap number, but doing so would be invasive and would entail non-trivial overhead.
2015-06-16switch sh port's __unmapself to generic version when running on sh2/nommuRich Felker-3/+3
due to the way the interrupt and syscall trap mechanism works, userspace on sh2 must never set the stack pointer to an invalid value. thus, the approach used on most archs, where __unmapself executes with no stack for the interval between SYS_munmap and SYS_exit, is not viable on sh2. in order not to pessimize sh3/sh4, the sh asm version of __unmapself is not removed. instead it's renamed and redirected through code that calls either the generic (safe) __unmapself or the sh3/sh4 asm, depending on compile-time and run-time conditions.
2015-06-16add support for sh2 interrupt-masking-based atomics to sh portRich Felker-6/+0
the sh2 target is being considered an ISA subset of sh3/sh4, in the sense that binaries built for sh2 are intended to be usable on later cpu models/kernels with mmu support. so rather than hard-coding sh2-specific atomics, the runtime atomic selection mechanisms that was already in place has been extended to add sh2 atomics. at this time, the sh2 atomics are not SMP-compatible; since the ISA lacks actual atomic operations, the new code instead masks interrupts for the duration of the atomic operation, producing an atomic result on single-core. this is only possible because the kernel/hardware does not impose protections against userspace doing so. additional changes will be needed to support future SMP systems. care has been taken to avoid producing significant additional code size in the case where it's known at compile-time that the target is not sh2 and does not need sh2-specific code.
2015-04-17fix sh build regressions in asmRich Felker-1/+1
even hidden functions need @PLT symbol references; otherwise an absolute address is produced instead of a PC-relative one.
2015-04-17fix sh __set_thread_area uninitialized return valueRich Felker-1/+2
this caused the dynamic linker/startup code to abort when r0 happened to contain a negative value.
2015-04-14consistently use hidden visibility for cancellable syscall internalsRich Felker-3/+9
in a few places, non-hidden symbols were referenced from asm in ways that assumed ld-time binding. while these is no semantic reason these symbols need to be hidden, fixing the references without making them hidden was going to be ugly, and hidden reduces some bloat anyway. in the asm files, .global/.hidden directives have been moved to the top to unclutter the actual code.
2014-02-27rename superh port to "sh" for consistencyRich Felker-0/+113
linux, gcc, etc. all use "sh" as the name for the superh arch. there was already some inconsistency internally in musl: the dynamic linker was searching for "ld-musl-sh.path" as its path file despite its own name being "". there was some sentiment in both directions as to how to resolve the inconsistency, but overall "sh" was favored.