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x86/vdso: Give the [ph]vclock_page declarations real types 

Clean up the vDSO code a bit by giving pvclock_page and hvclock_page
their actual types instead of u8[PAGE_SIZE].  This shouldn't
materially affect the generated code.

Heavily based on a patch from Linus.

[ tglx: Adapted to the unified VDSO code ]

Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/6920c5188f8658001af1fc56fd35b815706d300c.1561241273.git.luto@kernel.org
This commit is contained in:
Andy Lutomirski 2019-06-22 15:08:18 -07:00 committed by Thomas Gleixner
parent 22ca962288
commit ecf9db3d1f
1 changed files with 24 additions and 12 deletions
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36
arch/x86/include/asm/vdso/gettimeofday.h
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@ -26,13 +26,33 @@
#define VDSO_HAS_CLOCK_GETRES 1
/*
* Declare the memory-mapped vclock data pages. These come from hypervisors.
* If we ever reintroduce something like direct access to an MMIO clock like
* the HPET again, it will go here as well.
*
* A load from any of these pages will segfault if the clock in question is
* disabled, so appropriate compiler barriers and checks need to be used
* to prevent stray loads.
*
* These declarations MUST NOT be const. The compiler will assume that
* an extern const variable has genuinely constant contents, and the
* resulting code won't work, since the whole point is that these pages
* change over time, possibly while we're accessing them.
*/
#ifdef CONFIG_PARAVIRT_CLOCK
extern u8 pvclock_page[PAGE_SIZE]
/*
* This is the vCPU 0 pvclock page. We only use pvclock from the vDSO
* if the hypervisor tells us that all vCPUs can get valid data from the
* vCPU 0 page.
*/
extern struct pvclock_vsyscall_time_info pvclock_page
__attribute__((visibility("hidden")));
#endif
#ifdef CONFIG_HYPERV_TSCPAGE
extern u8 hvclock_page[PAGE_SIZE]
extern struct ms_hyperv_tsc_page hvclock_page
__attribute__((visibility("hidden")));
#endif
@ -131,14 +151,9 @@ clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
#endif
#ifdef CONFIG_PARAVIRT_CLOCK
static const struct pvclock_vsyscall_time_info *get_pvti0(void)
{
return (const struct pvclock_vsyscall_time_info *)&pvclock_page;
}
static u64 vread_pvclock(void)
{
const struct pvclock_vcpu_time_info *pvti = &get_pvti0()->pvti;
const struct pvclock_vcpu_time_info *pvti = &pvclock_page.pvti;
u32 version;
u64 ret;
@ -180,10 +195,7 @@ static u64 vread_pvclock(void)
#ifdef CONFIG_HYPERV_TSCPAGE
static u64 vread_hvclock(void)
{
const struct ms_hyperv_tsc_page *tsc_pg =
(const struct ms_hyperv_tsc_page *)&hvclock_page;
return hv_read_tsc_page(tsc_pg);
return hv_read_tsc_page(&hvclock_page);
}
#endif