The code, #undef CONFIG_OPTIMIZE_INLINING, is not working as expected
because <linux/compiler_types.h> is parsed before vclock_gettime.c since
28128c61e0 ("kconfig.h: Include compiler types to avoid missed struct
attributes").
Since then, <linux/compiler_types.h> is included really early by using the
'-include' option. So, you cannot negate the decision of
<linux/compiler_types.h> in this way.
You can confirm it by checking the pre-processed code, like this:
$ make arch/x86/entry/vdso/vdso32/vclock_gettime.i
There is no difference with/without CONFIG_CC_OPTIMIZE_FOR_SIZE.
It is about two years since 28128c61e0. Nobody has reported a problem
(or, nobody has even noticed the fact that this code is not working).
It is ugly and unreliable to attempt to undefine a CONFIG option from C
files, and anyway the inlining heuristic is up to the compiler.
Just remove the broken code.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: David Miller <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20200220110807.32534-1-masahiroy@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Older versions of bintutils do not allow symbol math across different
segments on sparc:
====================
Assembler messages:
99: Error: operation combines symbols in different segments
====================
This is controlled by whether or not DIFF_EXPR_OK is defined in
gas/config/tc-*.h and for sparc this was not the case until mid-2017.
So we have to patch between %stick and %tick another way.
Do what powerpc does and emit two versions of the relevant functions,
one using %tick and one using %stick, and patch the symbols in the
dynamic symbol table.
Fixes: 2f6c9bf31a ("sparc: Improve VDSO instruction patching.")
Reported-by: Meelis Roos <mroos@linux.ee>
Tested-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: David S. Miller <davem@davemloft.net>
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>
Masahiro Yamada
David S. Miller
Nagarathnam Muthusamy