Commit-ID: ecf9db3d1f1a8fd2c335148891c3b044e9ce0628 Gitweb: https://git.kernel.org/tip/ecf9db3d1f1a8fd2c335148891c3b044e9ce0628 Author: Andy Lutomirski <l...@kernel.org> AuthorDate: Sat, 22 Jun 2019 15:08:18 -0700 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Mon, 24 Jun 2019 01:21:31 +0200
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 <torva...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Andy Lutomirski <l...@kernel.org> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Cc: Borislav Petkov <b...@alien8.de> Cc: Peter Zijlstra <pet...@infradead.org> Link: https://lkml.kernel.org/r/6920c5188f8658001af1fc56fd35b815706d300c.1561241273.git.l...@kernel.org --- arch/x86/include/asm/vdso/gettimeofday.h | 36 +++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h index f92752d6cbcf..5b63f1f78a1f 100644 --- a/arch/x86/include/asm/vdso/gettimeofday.h +++ b/arch/x86/include/asm/vdso/gettimeofday.h @@ -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
