delta/go-git.git/src/runtime/sys_linux_ppc64x.s, branch dev.debug

runtime: inform arena placement using sbrk(0)

2017-04-21T14:34:10+00:00

On 32-bit architectures (or if we fail to map a 64-bit-style arena),
we try to map the heap arena just above the end of the process image.
While we can accept any address, using lower addresses is preferable
because lower addresses cause us to map less of the heap bitmap.

However, if a program is linked against C code that has global
constructors, those constructors may call brk/sbrk to allocate memory
(e.g., many C malloc implementations do this for small allocations).
The brk also starts just above the process image, so this may adjust
the brk past the beginning of where we want to put the heap arena. In
this case, the kernel will pick a different address for the arena and
it will usually be very high (at least, as these things go in a 32-bit
address space).

Fix this by consulting the current value of the brk and using this in
addition to the end of the process image to compute the initial arena
placement.

This is implemented only on Linux currently, since we have no evidence
that it's an issue on any other OSes.

Fixes #19831.

Change-Id: Id64b45d08d8c91e4f50d92d0339146250b04f2f8
Reviewed-on: https://go-review.googlesource.com/39810
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor

cmd/asm: detect invalid DS form offsets for ppc64x

2017-04-17T21:24:35+00:00

While debugging a recent regression it was discovered that
the assembler for ppc64x was not always generating the correct
instruction for DS form loads and stores.  When an instruction
is DS form then the offset must be a multiple of 4, and if it
isn't then bits outside the offset field were being incorrectly
set resulting in unexpected and incorrect instructions.

This change adds a check to determine when the opcode is DS form
and then verifies that the offset is a multiple of 4 before
generating the instruction, otherwise logs an error.

This also changes a few asm files that were using unaligned offsets
for DS form loads and stores.  In the runtime package these were
instructions intended to cause a crash so using aligned or unaligned
offsets doesn't change that behavior.

Change-Id: Ie3a7e1e65dcc9933b54de7a46a054da8459cb56f
Reviewed-on: https://go-review.googlesource.com/40476
Reviewed-by: Michael Hudson-Doyle

time: record monotonic clock reading in time.Now, for more accurate comparisons

2017-02-03T19:04:52+00:00

See https://golang.org/design/12914-monotonic for details.

Fixes #12914.

Change-Id: I80edc2e6c012b4ace7161c84cf067d444381a009
Reviewed-on: https://go-review.googlesource.com/36255
Run-TryBot: Russ Cox 
TryBot-Result: Gobot Gobot 
Reviewed-by: Caleb Spare 
Reviewed-by: Ian Lance Taylor

runtime: unify some signal handling functions

2016-09-24T01:39:48+00:00

Unify the OS-specific versions of msigsave, msigrestore, sigblock,
updatesigmask, and unblocksig into single versions in signal_unix.go.
To do this, make sigprocmask work the same way on all systems, which
required adding a definition of sigprocmask for linux and openbsd.
Also add a single OS-specific function sigmaskToSigset.

Change-Id: I7cbf75131dddb57eeefe648ef845b0791404f785
Reviewed-on: https://go-review.googlesource.com/29689
Run-TryBot: Ian Lance Taylor 
TryBot-Result: Gobot Gobot 
Reviewed-by: David Crawshaw

all: fix assembly vet issues

2016-08-25T18:52:31+00:00

Add missing function prototypes.
Fix function prototypes.
Use FP references instead of SP references.
Fix variable names.
Update comments.
Clean up whitespace. (Not for vet.)

All fairly minor fixes to make vet happy.

Updates #11041

Change-Id: Ifab2cdf235ff61cdc226ab1d84b8467b5ac9446c
Reviewed-on: https://go-review.googlesource.com/27713
Run-TryBot: Josh Bleecher Snyder 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

runtime: Use clock_gettime to get current time on ppc64x

2016-08-23T05:37:05+00:00

Fetch the current time in nanoseconds, not microseconds, by using
clock_gettime rather than gettimeofday.

Updates #11222

Change-Id: I1c2c1b88f80ae82002518359436e19099061c6fb
Reviewed-on: https://go-review.googlesource.com/26790
Reviewed-by: Brad Fitzpatrick 
Reviewed-by: Lynn Boger 
Reviewed-by: Minux Ma

runtime: support symbolic backtrace of C code in a cgo crash

2016-04-01T04:13:44+00:00

The new function runtime.SetCgoTraceback may be used to register stack
traceback and symbolizer functions, written in C, to do a stack
traceback from cgo code.

There is a sample implementation of runtime.SetCgoSymbolizer at
github.com/ianlancetaylor/cgosymbolizer.  Just importing that package is
sufficient to get symbolic C backtraces.

Currently only supported on linux/amd64.

Change-Id: If96ee2eb41c6c7379d407b9561b87557bfe47341
Reviewed-on: https://go-review.googlesource.com/17761
Reviewed-by: Austin Clements

runtime: fix errno sign for some mmap and mincore cases

2016-02-12T00:07:29+00:00

The caller of mmap expects it to return a positive errno value, but the
linux-arm64 and nacl-386 system calls returned a negative errno value.
Correct them to negate the errno value.

The caller of mincore expects it to return a negative errno value (yes,
this is inconsistent), but the linux-mips64x and linux-ppc64x system
call returned a positive errno value.  Correct them to negate the errno
value.

Add a test that mmap returns errno with the correct sign.  Brad added a
test for mincore's errno value in https://golang.org/cl/19457.

Fixes #14297.

Change-Id: I2b93f32e679bd1eae1c9aef9ae7bcf0ba39521b5
Reviewed-on: https://go-review.googlesource.com/19455
Reviewed-by: Brad Fitzpatrick 
Reviewed-by: Minux Ma 
Run-TryBot: Ian Lance Taylor 
TryBot-Result: Gobot Gobot

cmd/compile, cmd/link, runtime: on ppc64x, maintain the TOC pointer in R2 when compiling PIC

2015-11-12T23:18:58+00:00

The PowerPC ISA does not have a PC-relative load instruction, which poses
obvious challenges when generating position-independent code. The way the ELFv2
ABI addresses this is to specify that r2 points to a per "module" (shared
library or executable) TOC pointer. Maintaining this pointer requires
cooperation between codegen and the system linker:

 * Non-leaf functions leave space on the stack at r1+24 to save the TOC pointer.
 * A call to a function that *might* have to go via a PLT stub must be followed
   by a nop instruction that the system linker can replace with "ld r1, 24(r1)"
   to restore the TOC pointer (only when dynamically linking Go code).
 * When calling a function via a function pointer, the address of the function
   must be in r12, and the first couple of instructions (the "global entry
   point") of the called function use this to derive the address of the TOC
   for the module it is in.
 * When calling a function that is implemented in the same module, the system
   linker adjusts the call to skip over the instructions mentioned above (the
   "local entry point"), assuming that r2 is already correctly set.

So this changeset adds the global entry point instructions, sets the metadata so
the system linker knows where the local entry point is, inserts code to save the
TOC pointer at 24(r1), adds a nop after any call not known to be local and copes
with the odd non-local code transfer in the runtime (e.g. the stuff around
jmpdefer). It does not actually compile PIC yet.

Change-Id: I7522e22bdfd2f891745a900c60254fe9e372c854
Reviewed-on: https://go-review.googlesource.com/15967
Reviewed-by: Russ Cox

runtime, runtime/cgo: conform to PIC register use rules in ppc64 asm

2015-10-18T23:36:39+00:00

PIC code on ppc64le uses R2 as a TOC pointer and when calling a function
through a function pointer must ensure the function pointer is in R12.  These
rules are easy enough to follow unconditionally in our assembly, so do that.

Change-Id: Icfc4e47ae5dfbe15f581cbdd785cdeed6e40bc32
Reviewed-on: https://go-review.googlesource.com/15526
Reviewed-by: Ian Lance Taylor