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| author | Sven Schnelle <svens@linux.ibm.com> | 2020-04-28 09:52:23 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2020-08-26 18:47:21 +0200 |
| commit | 4bff8cb5450287e246d365b719148b2d9364c292 (patch) | |
| tree | 4cc4c378f7541d4b8fd080663d2f0847a24c2cfc /arch/s390/kernel/entry.S | |
| parent | 98ad45fb58c14ebef6da27f91905e5b8fcff8686 (diff) | |
s390: convert to GENERIC_VDSO
Convert s390 to generic vDSO. There are a few special things on s390:
- vDSO can be called without a stack frame - glibc did this in the past.
So we need to allocate a stackframe on our own.
- The former assembly code used stcke to get the TOD clock and applied
time steering to it. We need to do the same in the new code. This is done
in the architecture specific __arch_get_hw_counter function. The steering
information is stored in an architecure specific area in the vDSO data.
- CPUCLOCK_VIRT is now handled with a syscall fallback, which might
be slower/less accurate than the old implementation.
The getcpu() function stays as an assembly function because there is no
generic implementation and the code is just a few lines.
Performance number from my system do 100 mio gettimeofday() calls:
Plain syscall: 8.6s
Generic VDSO: 1.3s
old ASM VDSO: 1s
So it's a bit slower but still much faster than syscalls.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel/entry.S')
| -rw-r--r-- | arch/s390/kernel/entry.S | 6 |
1 files changed, 0 insertions, 6 deletions
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 23edf196d3dc..86235919c2d1 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -435,10 +435,8 @@ ENTRY(system_call) jz .Lsysc_skip_fpu brasl %r14,load_fpu_regs .Lsysc_skip_fpu: - lg %r14,__LC_VDSO_PER_CPU mvc __LC_RETURN_PSW(16),__PT_PSW(%r11) stpt __LC_EXIT_TIMER - mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER lmg %r0,%r15,__PT_R0(%r11) b __LC_RETURN_LPSWE @@ -797,13 +795,11 @@ ENTRY(io_int_handler) TRACE_IRQS_ON 0: #endif - lg %r14,__LC_VDSO_PER_CPU mvc __LC_RETURN_PSW(16),__PT_PSW(%r11) tm __PT_PSW+1(%r11),0x01 # returning to user ? jno .Lio_exit_kernel BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP stpt __LC_EXIT_TIMER - mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER .Lio_exit_kernel: lmg %r0,%r15,__PT_R0(%r11) b __LC_RETURN_LPSWE @@ -1213,14 +1209,12 @@ ENTRY(mcck_int_handler) brasl %r14,s390_handle_mcck TRACE_IRQS_ON .Lmcck_return: - lg %r14,__LC_VDSO_PER_CPU lmg %r0,%r10,__PT_R0(%r11) mvc __LC_RETURN_MCCK_PSW(16),__PT_PSW(%r11) # move return PSW tm __LC_RETURN_MCCK_PSW+1,0x01 # returning to user ? jno 0f BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP stpt __LC_EXIT_TIMER - mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER 0: lmg %r11,%r15,__PT_R11(%r11) b __LC_RETURN_MCCK_LPSWE |