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Date: Tue, 19 Jul 2011 11:53:07 +0100
From: "Jan Beulich" <JBeulich@...ell.com>
To: <mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc: <mjg@...hat.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86: serialize EFI time accesses on rtc_lock
The EFI specification requires that callers of the time related runtime
functions serialize with other CMOS accesses in the kernel, as the EFI
time functions may choose to also use the legacy CMOS RTC.
Besides fixing a latent bug, this is a prerequisite to safely enable
the rtc-efi driver for x86, which ought to be preferred over rtc-cmos
on all EFI platforms.
Signed-off-by: Jan Beulich <jbeulich@...ell.com>
Cc: Matthew Garrett <mjg@...hat.com>
---
arch/x86/platform/efi/efi.c | 39 +++++++++++++++++++++++++++++++++------
1 file changed, 33 insertions(+), 6 deletions(-)
--- 3.0-rc7/arch/x86/platform/efi/efi.c
+++ 3.0-rc7-x86-rtc-lock-EFI/arch/x86/platform/efi/efi.c
@@ -79,26 +79,50 @@ early_param("add_efi_memmap", setup_add_
static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
{
- return efi_call_virt2(get_time, tm, tc);
+ unsigned long flags;
+ efi_status_t status;
+
+ spin_lock_irqsave(&rtc_lock, flags);
+ status = efi_call_virt2(get_time, tm, tc);
+ spin_unlock_irqrestore(&rtc_lock, flags);
+ return status;
}
static efi_status_t virt_efi_set_time(efi_time_t *tm)
{
- return efi_call_virt1(set_time, tm);
+ unsigned long flags;
+ efi_status_t status;
+
+ spin_lock_irqsave(&rtc_lock, flags);
+ status = efi_call_virt1(set_time, tm);
+ spin_unlock_irqrestore(&rtc_lock, flags);
+ return status;
}
static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
efi_bool_t *pending,
efi_time_t *tm)
{
- return efi_call_virt3(get_wakeup_time,
- enabled, pending, tm);
+ unsigned long flags;
+ efi_status_t status;
+
+ spin_lock_irqsave(&rtc_lock, flags);
+ status = efi_call_virt3(get_wakeup_time,
+ enabled, pending, tm);
+ spin_unlock_irqrestore(&rtc_lock, flags);
+ return status;
}
static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
{
- return efi_call_virt2(set_wakeup_time,
- enabled, tm);
+ unsigned long flags;
+ efi_status_t status;
+
+ spin_lock_irqsave(&rtc_lock, flags);
+ status = efi_call_virt2(set_wakeup_time,
+ enabled, tm);
+ spin_unlock_irqrestore(&rtc_lock, flags);
+ return status;
}
static efi_status_t virt_efi_get_variable(efi_char16_t *name,
@@ -164,11 +188,14 @@ static efi_status_t __init phys_efi_set_
static efi_status_t __init phys_efi_get_time(efi_time_t *tm,
efi_time_cap_t *tc)
{
+ unsigned long flags;
efi_status_t status;
+ spin_lock_irqsave(&rtc_lock, flags);
efi_call_phys_prelog();
status = efi_call_phys2(efi_phys.get_time, tm, tc);
efi_call_phys_epilog();
+ spin_unlock_irqrestore(&rtc_lock, flags);
return status;
}
--
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