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Subject[RFC v2 19/26] mm/asi: Add option to map RCU data
Date
Add an option to map RCU data when creating an ASI. This will map
the percpu rcu_data (which is not exported by the kernel), and
allow ASI to use RCU without faulting.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
arch/x86/include/asm/asi.h | 1 +
arch/x86/mm/asi.c | 4 ++++
2 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/asi.h b/arch/x86/include/asm/asi.h
index a277e43..8199618 100644
--- a/arch/x86/include/asm/asi.h
+++ b/arch/x86/include/asm/asi.h
@@ -18,6 +18,7 @@
#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 */
+#define ASI_MAP_RCU_DATA 0x08 /* map rcu data */

enum page_table_level {
PGT_LEVEL_PTE,
diff --git a/arch/x86/mm/asi.c b/arch/x86/mm/asi.c
index acd1135..20c23dc 100644
--- a/arch/x86/mm/asi.c
+++ b/arch/x86/mm/asi.c
@@ -7,6 +7,7 @@

#include <linux/export.h>
#include <linux/gfp.h>
+#include <linux/irq_work.h>
#include <linux/mm.h>
#include <linux/printk.h>
#include <linux/sched/debug.h>
@@ -16,6 +17,8 @@
#include <asm/bug.h>
#include <asm/mmu_context.h>

+#include "../../../kernel/rcu/tree.h"
+
/* ASI sessions, one per cpu */
DEFINE_PER_CPU_PAGE_ALIGNED(struct asi_session, cpu_asi_session);

@@ -29,6 +32,7 @@ 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) },
+ { ASI_MAP_RCU_DATA, &rcu_data, sizeof(rcu_data) },
};

static void asi_log_fault(struct asi *asi, struct pt_regs *regs,
--
1.7.1
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