mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
![Tejun Heo](/assets/img/avatar_default.png)
Impact: pt_regs changed, lazy gs handling made optional, add slight overhead to SAVE_ALL, simplifies error_code path a bit On x86_32, %gs hasn't been used by kernel and handled lazily. pt_regs doesn't have place for it and gs is saved/loaded only when necessary. In preparation for stack protector support, this patch makes lazy %gs handling optional by doing the followings. * Add CONFIG_X86_32_LAZY_GS and place for gs in pt_regs. * Save and restore %gs along with other registers in entry_32.S unless LAZY_GS. Note that this unfortunately adds "pushl $0" on SAVE_ALL even when LAZY_GS. However, it adds no overhead to common exit path and simplifies entry path with error code. * Define different user_gs accessors depending on LAZY_GS and add lazy_save_gs() and lazy_load_gs() which are noop if !LAZY_GS. The lazy_*_gs() ops are used to save, load and clear %gs lazily. * Define ELF_CORE_COPY_KERNEL_REGS() which always read %gs directly. xen and lguest changes need to be verified. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
92 lines
2.1 KiB
C
92 lines
2.1 KiB
C
#ifndef _ASM_X86_MMU_CONTEXT_H
|
|
#define _ASM_X86_MMU_CONTEXT_H
|
|
|
|
#include <asm/desc.h>
|
|
#include <asm/atomic.h>
|
|
#include <asm/pgalloc.h>
|
|
#include <asm/tlbflush.h>
|
|
#include <asm/paravirt.h>
|
|
#ifndef CONFIG_PARAVIRT
|
|
#include <asm-generic/mm_hooks.h>
|
|
|
|
static inline void paravirt_activate_mm(struct mm_struct *prev,
|
|
struct mm_struct *next)
|
|
{
|
|
}
|
|
#endif /* !CONFIG_PARAVIRT */
|
|
|
|
/*
|
|
* Used for LDT copy/destruction.
|
|
*/
|
|
int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
|
|
void destroy_context(struct mm_struct *mm);
|
|
|
|
|
|
static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
|
|
{
|
|
#ifdef CONFIG_SMP
|
|
if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
|
|
percpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
|
|
#endif
|
|
}
|
|
|
|
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
|
|
struct task_struct *tsk)
|
|
{
|
|
unsigned cpu = smp_processor_id();
|
|
|
|
if (likely(prev != next)) {
|
|
/* stop flush ipis for the previous mm */
|
|
cpu_clear(cpu, prev->cpu_vm_mask);
|
|
#ifdef CONFIG_SMP
|
|
percpu_write(cpu_tlbstate.state, TLBSTATE_OK);
|
|
percpu_write(cpu_tlbstate.active_mm, next);
|
|
#endif
|
|
cpu_set(cpu, next->cpu_vm_mask);
|
|
|
|
/* Re-load page tables */
|
|
load_cr3(next->pgd);
|
|
|
|
/*
|
|
* load the LDT, if the LDT is different:
|
|
*/
|
|
if (unlikely(prev->context.ldt != next->context.ldt))
|
|
load_LDT_nolock(&next->context);
|
|
}
|
|
#ifdef CONFIG_SMP
|
|
else {
|
|
percpu_write(cpu_tlbstate.state, TLBSTATE_OK);
|
|
BUG_ON(percpu_read(cpu_tlbstate.active_mm) != next);
|
|
|
|
if (!cpu_test_and_set(cpu, next->cpu_vm_mask)) {
|
|
/* We were in lazy tlb mode and leave_mm disabled
|
|
* tlb flush IPI delivery. We must reload CR3
|
|
* to make sure to use no freed page tables.
|
|
*/
|
|
load_cr3(next->pgd);
|
|
load_LDT_nolock(&next->context);
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
|
|
#define activate_mm(prev, next) \
|
|
do { \
|
|
paravirt_activate_mm((prev), (next)); \
|
|
switch_mm((prev), (next), NULL); \
|
|
} while (0);
|
|
|
|
#ifdef CONFIG_X86_32
|
|
#define deactivate_mm(tsk, mm) \
|
|
do { \
|
|
lazy_load_gs(0); \
|
|
} while (0)
|
|
#else
|
|
#define deactivate_mm(tsk, mm) \
|
|
do { \
|
|
load_gs_index(0); \
|
|
loadsegment(fs, 0); \
|
|
} while (0)
|
|
#endif
|
|
|
|
#endif /* _ASM_X86_MMU_CONTEXT_H */
|