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Subject[RFC v2 16/26] mm/asi: Option to map current task into ASI
Date
Add an option to map the current task into an ASI page-table.
The task is mapped when entering isolation and unmapped on
abort/exit.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
arch/x86/include/asm/asi.h | 2 ++
arch/x86/mm/asi.c | 25 +++++++++++++++++++++----
arch/x86/mm/asi_pagetable.c | 4 ++--
3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/asi.h b/arch/x86/include/asm/asi.h
index 1ac8fd3..a277e43 100644
--- a/arch/x86/include/asm/asi.h
+++ b/arch/x86/include/asm/asi.h
@@ -17,6 +17,7 @@
*/
#define ASI_MAP_STACK_CANARY 0x01 /* map stack canary */
#define ASI_MAP_CPU_PTR 0x02 /* for get_cpu_var()/this_cpu_ptr() */
+#define ASI_MAP_CURRENT_TASK 0x04 /* map the current task */

enum page_table_level {
PGT_LEVEL_PTE,
@@ -31,6 +32,7 @@ enum page_table_level {
struct asi {
spinlock_t lock; /* protect all attributes */
pgd_t *pgd; /* ASI page-table */
+ int mapping_flags; /* map flags */
struct list_head mapping_list; /* list of VA range mapping */

/*
diff --git a/arch/x86/mm/asi.c b/arch/x86/mm/asi.c
index f049438..acd1135 100644
--- a/arch/x86/mm/asi.c
+++ b/arch/x86/mm/asi.c
@@ -28,6 +28,7 @@ struct asi_map_option {
struct asi_map_option asi_map_percpu_options[] = {
{ ASI_MAP_STACK_CANARY, &fixed_percpu_data, sizeof(fixed_percpu_data) },
{ ASI_MAP_CPU_PTR, &this_cpu_off, sizeof(this_cpu_off) },
+ { ASI_MAP_CURRENT_TASK, &current_task, sizeof(current_task) },
};

static void asi_log_fault(struct asi *asi, struct pt_regs *regs,
@@ -96,8 +97,9 @@ bool asi_fault(struct pt_regs *regs, unsigned long error_code,
return true;
}

-static int asi_init_mapping(struct asi *asi, int flags)
+static int asi_init_mapping(struct asi *asi)
{
+ int flags = asi->mapping_flags;
struct asi_map_option *option;
int i, err;

@@ -164,8 +166,9 @@ struct asi *asi_create(int map_flags)
spin_lock_init(&asi->lock);
spin_lock_init(&asi->fault_lock);
asi_init_backend(asi);
+ asi->mapping_flags = map_flags;

- err = asi_init_mapping(asi, map_flags);
+ err = asi_init_mapping(asi);
if (err)
goto error;

@@ -248,6 +251,15 @@ int asi_enter(struct asi *asi)
goto err_clear_asi;

/*
+ * Optionally, also map the current task.
+ */
+ if (asi->mapping_flags & ASI_MAP_CURRENT_TASK) {
+ err = asi_map(asi, current, sizeof(struct task_struct));
+ if (err)
+ goto err_unmap_stack;
+ }
+
+ /*
* Instructions ordering is important here because we should be
* able to deal with any interrupt/exception which will abort
* the isolation and restore CR3 to its original value:
@@ -269,7 +281,7 @@ int asi_enter(struct asi *asi)
if (!original_cr3) {
WARN_ON(1);
err = -EINVAL;
- goto err_unmap_stack;
+ goto err_unmap_task;
}
asi_session->original_cr3 = original_cr3;

@@ -286,6 +298,9 @@ int asi_enter(struct asi *asi)

return 0;

+err_unmap_task:
+ if (asi->mapping_flags & ASI_MAP_CURRENT_TASK)
+ asi_unmap(asi, current);
err_unmap_stack:
asi_unmap(asi, current->stack);
err_clear_asi:
@@ -345,8 +360,10 @@ void asi_exit(struct asi *asi)
*/
asi_session->abort_depth = 0;

- /* unmap stack */
+ /* unmap stack and task */
asi_unmap(asi, current->stack);
+ if (asi->mapping_flags & ASI_MAP_CURRENT_TASK)
+ asi_unmap(asi, current);
}
EXPORT_SYMBOL(asi_exit);

diff --git a/arch/x86/mm/asi_pagetable.c b/arch/x86/mm/asi_pagetable.c
index bcc95f2..8076626 100644
--- a/arch/x86/mm/asi_pagetable.c
+++ b/arch/x86/mm/asi_pagetable.c
@@ -714,7 +714,7 @@ int asi_map_range(struct asi *asi, void *ptr, size_t size,
* Don't log info the current stack because it is mapped/unmapped
* everytime we enter/exit isolation.
*/
- if (ptr != current->stack) {
+ if (ptr != current->stack && ptr != current) {
pr_debug("ASI %p: MAP %px/%lx/%d -> %lx-%lx\n",
asi, ptr, size, level, map_addr, map_end);
if (map_addr < addr)
@@ -1001,7 +1001,7 @@ void asi_unmap(struct asi *asi, void *ptr)
* Don't log info the current stack because it is mapped/unmapped
* everytime we enter/exit isolation.
*/
- if (ptr != current->stack) {
+ if (ptr != current->stack && ptr != current) {
pr_debug("ASI %p: UNMAP %px/%lx/%d\n", asi, ptr,
range_mapping->size, range_mapping->level);
}
--
1.7.1
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