Following patch is based on work done by Nick Alcock on 64-bit vDSO for sparc
in Oracle linux. I have extended it to include support for 32-bit vDSO for sparc
on 64-bit kernel.
vDSO for sparc is based on the X86 implementation. This patch
provides vDSO support for both 64-bit and 32-bit programs on 64-bit kernel.
vDSO will be disabled on 32-bit linux kernel on sparc.
*) vclock_gettime.c contains all the vdso functions. Since data page is mapped
before the vdso code page, the pointer to data page is got by subracting offset
from an address in the vdso code page. The return address stored in
%i7 is used for this purpose.
*) During compilation, both 32-bit and 64-bit vdso images are compiled and are
converted into raw bytes by vdso2c program to be ready for mapping into the
process. 32-bit images are compiled only if CONFIG_COMPAT is enabled. vdso2c
generates two files vdso-image-64.c and vdso-image-32.c which contains the
respective vDSO image in C structure.
*) During vdso initialization, required number of vdso pages are allocated and
raw bytes are copied into the pages.
*) During every exec, these pages are mapped into the process through
arch_setup_additional_pages and the location of mapping is passed on to the
process through aux vector AT_SYSINFO_EHDR which is used by glibc.
*) A new update_vsyscall routine for sparc is added to keep the data page in
vdso updated.
*) As vDSO cannot contain dynamically relocatable references, a new version of
cpu_relax is added for the use of vDSO.
This change also requires a putback to glibc to use vDSO. For testing,
programs planning to try vDSO can be compiled against the generated
vdso(64/32).so in the source.
Testing:
========
[root@localhost ~]# cat vdso_test.c
int main() {
struct timespec tv_start, tv_end;
struct timeval tv_tmp;
int i;
int count = 1 * 1000 * 10000;
long long diff;
clock_gettime(0, &tv_start);
for (i = 0; i < count; i++)
gettimeofday(&tv_tmp, NULL);
clock_gettime(0, &tv_end);
diff = (long long)(tv_end.tv_sec -
tv_start.tv_sec)*(1*1000*1000*1000);
diff += (tv_end.tv_nsec - tv_start.tv_nsec);
printf("Start sec: %d\n", tv_start.tv_sec);
printf("End sec : %d\n", tv_end.tv_sec);
printf("%d cycles in %lld ns = %f ns/cycle\n", count, diff,
(double)diff / (double)count);
return 0;
}
[root@localhost ~]# cc vdso_test.c -o t32_without_fix -m32 -lrt
[root@localhost ~]# ./t32_without_fix
Start sec: 1502396130
End sec : 1502396140
10000000 cycles in 9565148528 ns = 956.514853 ns/cycle
[root@localhost ~]# cc vdso_test.c -o t32_with_fix -m32 ./vdso32.so.dbg
[root@localhost ~]# ./t32_with_fix
Start sec: 1502396168
End sec : 1502396169
10000000 cycles in 798141262 ns = 79.814126 ns/cycle
[root@localhost ~]# cc vdso_test.c -o t64_without_fix -m64 -lrt
[root@localhost ~]# ./t64_without_fix
Start sec: 1502396208
End sec : 1502396218
10000000 cycles in 9846091800 ns = 984.609180 ns/cycle
[root@localhost ~]# cc vdso_test.c -o t64_with_fix -m64 ./vdso64.so.dbg
[root@localhost ~]# ./t64_with_fix
Start sec: 1502396257
End sec : 1502396257
10000000 cycles in 380984048 ns = 38.098405 ns/cycle
V1 to V2 Changes:
=================
Added hot patching code to switch the read stick instruction to read
tick instruction based on the hardware.
V2 to V3 Changes:
=================
Merged latest changes from sparc-next and moved the initialization
of clocksource_tick.archdata.vclock_mode to time_init_early. Disabled
queued spinlock and rwlock configuration when simulating 32-bit config
to compile 32-bit VDSO.
V3 to V4 Changes:
=================
Hardcoded the page size as 8192 in linker script for both 64-bit and
32-bit binaries. Removed unused variables in vdso2c.h. Added -mv8plus flag to
Makefile to prevent the generation of relocation entries for __lshrdi3 in 32-bit
vdso binary.
Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Signed-off-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull sparc updates from David Miller:
1) Kill off support for sun4c and Cypress sun4m chips.
And as a result we were able to also kill off that ugly btfixup thing
that required multi-stage links of the final vmlinux image in the
Kbuild system. This should make the kbuild maintainers really happy.
Thanks a lot to Sam Ravnborg for his tireless efforts to get this
going.
2) Convert sparc64 to nobootmem. I suspect now with sparc32 being a lot
cleaner, it should be able to fall in line and modernize in this area
too.
3) Make sparc32 use generic clockevents, from Tkhai Kirill.
[ I fixed up the BPF rules, and tried to clean up the build rules too.
But I don't have - or want - a sparc cross-build environment, so the
BPF rule bug and the related build cleanup was all done with just a
bare "make -n" pseudo-test. - Linus ]
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next: (110 commits)
sparc32: use flushi when run-time patching in per_cpu_patch
sparc32: fix cpuid_patch run-time patching
sparc32: drop unused inline functions in srmmu.c
sparc32: drop unused functions in pgtsrmmu.h
sparc32,leon: move leon mmu functions to leon_mm.c
sparc32,leon: remove duplicate definitions in leon.h
sparc32,leon: remove duplicate UART register definitions
sparc32,leon: move leon ASI definitions to asi.h
sparc32: move trap table to a separate file
sparc64: renamed ttable.S to ttable_64.S
sparc32: Remove asm/sysen.h header.
sparc32: Delete asm/smpprim.h
sparc32: Remove unused empty_bad_page{,_table} declarations.
sparc32: Kill boot_cpu_id4
sparc32: Move GET_PROCESSOR*_ID() out of asm/asmmacro.h
sparc32: Remove completely unused code from asm/cache.h
sparc32: Add ucmpdi2.o to obj-y instead of lib-y.
sparc32: add ucmpdi2
sparc: introduce arch/sparc/Kbuild
sparc: remove obsolete documentation
...
This allows us to do:
make arch/sparc/
to build the core part of the sparc kernel.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
