alistair23-linux/arch/x86/kernel/paravirt_patch_32.c
Andy Lutomirski 9261e050b6 x86/asm/tsc, x86/paravirt: Remove read_tsc() and read_tscp() paravirt hooks
We've had ->read_tsc() and ->read_tscp() paravirt hooks since
the very beginning of paravirt, i.e.,

  d3561b7fa0 ("[PATCH] paravirt: header and stubs for paravirtualisation").

AFAICT, the only paravirt guest implementation that ever
replaced these calls was vmware, and it's gone. Arguably even
vmware shouldn't have hooked RDTSC -- we fully support systems
that don't have a TSC at all, so there's no point for a paravirt
implementation to pretend that we have a TSC but to replace it.

I also doubt that these hooks actually worked. Calls to rdtscl()
and rdtscll(), which respected the hooks, were used seemingly
interchangeably with native_read_tsc(), which did not.

Just remove them. If anyone ever needs them again, they can try
to make a case for why they need them.

Before, on a paravirt config:
  text    	data     bss     dec     hex filename
  12618257      1816384 1093632 15528273 ecf151 vmlinux

After:
  text		data     bss     dec     hex filename
  12617207      1816384 1093632 15527223 eced37 vmlinux

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm ML <kvm@vger.kernel.org>
Cc: virtualization@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/d08a2600fb298af163681e5efd8e599d889a5b97.1434501121.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06 15:23:26 +02:00

74 lines
2.1 KiB
C

#include <asm/paravirt.h>
DEF_NATIVE(pv_irq_ops, irq_disable, "cli");
DEF_NATIVE(pv_irq_ops, irq_enable, "sti");
DEF_NATIVE(pv_irq_ops, restore_fl, "push %eax; popf");
DEF_NATIVE(pv_irq_ops, save_fl, "pushf; pop %eax");
DEF_NATIVE(pv_cpu_ops, iret, "iret");
DEF_NATIVE(pv_cpu_ops, irq_enable_sysexit, "sti; sysexit");
DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax");
DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3");
DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax");
DEF_NATIVE(pv_cpu_ops, clts, "clts");
#if defined(CONFIG_PARAVIRT_SPINLOCKS) && defined(CONFIG_QUEUED_SPINLOCKS)
DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%eax)");
#endif
unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len)
{
/* arg in %eax, return in %eax */
return 0;
}
unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len)
{
/* arg in %edx:%eax, return in %edx:%eax */
return 0;
}
extern bool pv_is_native_spin_unlock(void);
unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
unsigned long addr, unsigned len)
{
const unsigned char *start, *end;
unsigned ret;
#define PATCH_SITE(ops, x) \
case PARAVIRT_PATCH(ops.x): \
start = start_##ops##_##x; \
end = end_##ops##_##x; \
goto patch_site
switch (type) {
PATCH_SITE(pv_irq_ops, irq_disable);
PATCH_SITE(pv_irq_ops, irq_enable);
PATCH_SITE(pv_irq_ops, restore_fl);
PATCH_SITE(pv_irq_ops, save_fl);
PATCH_SITE(pv_cpu_ops, iret);
PATCH_SITE(pv_cpu_ops, irq_enable_sysexit);
PATCH_SITE(pv_mmu_ops, read_cr2);
PATCH_SITE(pv_mmu_ops, read_cr3);
PATCH_SITE(pv_mmu_ops, write_cr3);
PATCH_SITE(pv_cpu_ops, clts);
#if defined(CONFIG_PARAVIRT_SPINLOCKS) && defined(CONFIG_QUEUED_SPINLOCKS)
case PARAVIRT_PATCH(pv_lock_ops.queued_spin_unlock):
if (pv_is_native_spin_unlock()) {
start = start_pv_lock_ops_queued_spin_unlock;
end = end_pv_lock_ops_queued_spin_unlock;
goto patch_site;
}
#endif
default:
ret = paravirt_patch_default(type, clobbers, ibuf, addr, len);
break;
patch_site:
ret = paravirt_patch_insns(ibuf, len, start, end);
break;
}
#undef PATCH_SITE
return ret;
}