Anybody has an idea if this patch is still relevant? None of the golang
tests I have conducted exposed any issues possibly related to lack of
arch_prctl SYSCALL.
On Wednesday, August 31, 2016 at 11:22:37 AM UTC-4, Nadav Har'El wrote:
>
>
> On Wed, Aug 31, 2016 at 4:04 PM, Benoit Canet <benoit.can...@gmail.com
> <javascript:>> wrote:
>
>> Needed by libraries produced by the Go compiler.
>>
>> With this patch and the golang app the runtime
>> init crash later because of a vdso issue.
>>
>> It can be examinated by insertion an abort()
>> before osv send SIGSEGV to the program.
>>
>> (gdb) bt
>> at /usr/lib/golang/src/runtime/mheap.go:503
>> argc=<error reading variable: Cannot access memory at address
>> 0xffffffffffffffcc>, argv=<optimized out>) at core/app.cc:338
>> Backtrace stopped: previous frame inner to this frame (corrupt stack?)
>> (gdb) frame 9
>> 188 CALL AX
>> (gdb) lsit
>> Undefined command: "lsit". Try "help".
>> (gdb) list
>> 183 RET
>> 184 fallback:
>> 185 LEAQ 0(SP), DI
>> 186 MOVQ $0, SI
>> 187 MOVQ runtime·__vdso_gettimeofday_sym(SB), AX
>> 188 CALL AX
>> 189 MOVQ 0(SP), AX // sec
>> 190 MOVL 8(SP), DX // usec
>> 191 IMULQ $1000, DX
>> 192 // sec is in AX, nsec in DX
>> (gdb) p $ax
>> $1 = 0
>> (gdb)
>>
>> Signed-off-by: Pekka Enberg <pen...@scylladb.com <javascript:>>
>> Signed-off-by: Benoît Canet <ben...@scylladb.com <javascript:>>
>> ---
>> Makefile | 1 +
>> arch/x64/msr.hh | 1 +
>> arch/x64/prctl.cc | 39 +++++++++++++++++++++++++++++++++++++++
>> linux.cc | 3 +++
>> 4 files changed, 44 insertions(+)
>> create mode 100644 arch/x64/prctl.cc
>>
>> diff --git a/Makefile b/Makefile
>> index e294a03..4518da8 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -882,6 +882,7 @@ objects += arch/x64/ioapic.o
>> objects += arch/x64/apic.o
>> objects += arch/x64/apic-clock.o
>> objects += arch/x64/entry-xen.o
>> +objects += arch/x64/prctl.o
>> objects += arch/x64/xen.o
>> objects += arch/x64/xen_intr.o
>> objects += core/sampler.o
>> diff --git a/arch/x64/msr.hh b/arch/x64/msr.hh
>> index d77c75c..9aa8314 100644
>> --- a/arch/x64/msr.hh
>> +++ b/arch/x64/msr.hh
>> @@ -62,6 +62,7 @@ enum class msr : uint32_t {
>> IA32_LSTAR = 0xc0000082,
>> IA32_FMASK = 0xc0000084,
>> IA32_FS_BASE = 0xc0000100,
>> + IA32_GS_BASE = 0xc0000101,
>>
>> KVM_WALL_CLOCK = 0x11,
>> KVM_SYSTEM_TIME = 0x12,
>> diff --git a/arch/x64/prctl.cc b/arch/x64/prctl.cc
>> new file mode 100644
>> index 0000000..73ba7c7
>> --- /dev/null
>> +++ b/arch/x64/prctl.cc
>> @@ -0,0 +1,39 @@
>> +/*
>> + * Copyright (C) 2014 Cloudius Systems, Ltd.
>> + *
>> + * This work is open source software, licensed under the terms of the
>> + * BSD license as described in the LICENSE file in the top-level
>> directory.
>> + */
>> +
>> +#include "arch.hh"
>> +#include "msr.hh"
>> +#include "libc/libc.hh"
>> +
>> +#include <assert.h>
>> +#include <stdio.h>
>> +
>> +enum {
>> + ARCH_SET_GS = 0x1001,
>> + ARCH_SET_FS = 0x1002,
>> + ARCH_GET_FS = 0x1003,
>> + ARCH_GET_GS = 0x1004,
>> +};
>> +
>> +long arch_prctl(int code, unsigned long addr)
>> +{
>> + switch (code) {
>> + case ARCH_SET_GS:
>> + processor::wrmsr(msr::IA32_GS_BASE, addr);
>> + asm volatile ("movq %0, %%gs" :: "r"(addr));
>>
>
> By the way, I think these "movq" things are wrong - I don't know what they
> are supposed to be doing?
>
>
>
>> + break;
>> + case ARCH_SET_FS:
>> + processor::wrmsr(msr::IA32_FS_BASE, addr);
>> + asm volatile ("movq %0, %%fs" :: "r"(addr));
>> + break;
>> + case ARCH_GET_FS:
>> + return processor::rdmsr(msr::IA32_FS_BASE);
>> + case ARCH_GET_GS:
>> + return processor::rdmsr(msr::IA32_GS_BASE);
>> + }
>> + return libc_error(EINVAL);
>> +}
>> diff --git a/linux.cc b/linux.cc
>> index e78bb0c..03be002 100644
>> --- a/linux.cc
>> +++ b/linux.cc
>> @@ -297,6 +297,8 @@ int rt_sigprocmask(int how, sigset_t * nset, sigset_t
>> * oset, size_t sigsetsize)
>> return sigprocmask(how, nset, oset);
>> }
>>
>> +extern long arch_prctl(int code, unsigned long addr);
>> +
>> long syscall(long number, ...)
>> {
>> switch (number) {
>> @@ -319,6 +321,7 @@ long syscall(long number, ...)
>> SYSCALL2(munmap, void *, size_t);
>> SYSCALL4(rt_sigaction, int, const struct k_sigaction *, struct
>> k_sigaction *, size_t);
>> SYSCALL4(rt_sigprocmask, int, sigset_t *, sigset_t *, size_t);
>> + SYSCALL2(arch_prctl, int, unsigned long);
>> }
>>
>> debug_always("syscall(): unimplemented system call %d\n", number);
>> --
>> 2.7.4
>>
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