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arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN

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With the ASID now installed in TTBR1, we can re-enable ARM64_SW_TTBR0_PAN
by ensuring that we switch to a reserved ASID of zero when disabling
user access and restore the active user ASID on the uaccess enable path.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon
2017-08-10 13:58:16 +01:00
parent 158d495899
commit 27a921e757
10 changed files with 42 additions and 21 deletions
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21
arch/arm64/include/asm/uaccess.h
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@@ -107,15 +107,19 @@ static inline void __uaccess_ttbr0_disable(void)
{
unsigned long ttbr;
ttbr = read_sysreg(ttbr1_el1);
/* reserved_ttbr0 placed at the end of swapper_pg_dir */
ttbr = read_sysreg(ttbr1_el1) + SWAPPER_DIR_SIZE;
write_sysreg(ttbr, ttbr0_el1);
write_sysreg(ttbr + SWAPPER_DIR_SIZE, ttbr0_el1);
isb();
/* Set reserved ASID */
ttbr &= ~(0xffffUL << 48);
write_sysreg(ttbr, ttbr1_el1);
isb();
}
static inline void __uaccess_ttbr0_enable(void)
{
unsigned long flags;
unsigned long flags, ttbr0, ttbr1;
/*
* Disable interrupts to avoid preemption between reading the 'ttbr0'
@@ -123,7 +127,16 @@ static inline void __uaccess_ttbr0_enable(void)
* roll-over and an update of 'ttbr0'.
*/
local_irq_save(flags);
write_sysreg(current_thread_info()->ttbr0, ttbr0_el1);
ttbr0 = current_thread_info()->ttbr0;
/* Restore active ASID */
ttbr1 = read_sysreg(ttbr1_el1);
ttbr1 |= ttbr0 & (0xffffUL << 48);
write_sysreg(ttbr1, ttbr1_el1);
isb();
/* Restore user page table */
write_sysreg(ttbr0, ttbr0_el1);
isb();
local_irq_restore(flags);
}