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soc: qcom: mem-offline: Clear page-table entries after offline

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After a memory block is offlined, the page-table entries should be removed
in order to avoid any CPU speculative accesses happening on this region.
Clear off the entries at the leaf levels (PUD or PMD) on a block mapped
memory region. This only zeroes the entries and does not free the page
table memory. During online, we create mappings again for these regions.

Change-Id: I71091c33589645567c60457ba569dd393ddcab59
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
This commit is contained in:
Sudarshan Rajagopalan
2019-03-14 15:33:45 -07:00
parent 4d8ce4ff50
commit 5ea86bc10f
3 changed files with 56 additions and 1 deletions
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8
arch/arm64/mm/mmu.c
View File

@@ -399,6 +399,14 @@ static phys_addr_t pgd_pgtable_alloc(void)
return __pa(ptr);
}
void create_pgtable_mapping(phys_addr_t start, phys_addr_t end)
{
unsigned long virt = (unsigned long)phys_to_virt(start);
__create_pgd_mapping(init_mm.pgd, start, virt, end - start,
PAGE_KERNEL, NULL, 0);
}
/*
* This function can only be used to modify existing table entries,
* without allocating new levels of table. Note that this permits the

47
drivers/soc/qcom/mem-offline.c
View File

@@ -16,6 +16,8 @@
#include <linux/of.h>
#include <linux/mailbox_client.h>
#include <linux/mailbox/qmp.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
#define AOP_MSG_ADDR_MASK 0xffffffff
#define AOP_MSG_ADDR_HIGH_SHIFT 32
@@ -50,6 +52,43 @@ static struct mem_offline_mailbox {
static struct section_stat *mem_info;
static void clear_pgtable_mapping(phys_addr_t start, phys_addr_t end)
{
unsigned long size = end - start;
unsigned long virt = (unsigned long)phys_to_virt(start);
unsigned long addr_end = virt + size;
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pgd = pgd_offset_k(virt);
while (virt < addr_end) {
/* Check if we have PUD section mapping */
pud = pud_offset(pgd, virt);
if (pud_sect(*pud)) {
pud_clear(pud);
virt += PUD_SIZE;
continue;
}
/* Check if we have PMD section mapping */
pmd = pmd_offset(pud, virt);
if (pmd_sect(*pmd)) {
pmd_clear(pmd);
virt += PMD_SIZE;
continue;
}
/* Clear mapping for page entry */
set_memory_valid(virt, 1, (int)false);
virt += PAGE_SIZE;
}
virt = (unsigned long)phys_to_virt(start);
flush_tlb_kernel_range(virt, addr_end);
}
void record_stat(unsigned long sec, ktime_t delay, int mode)
{
unsigned int total_sec = end_section_nr - start_section_nr + 1;
@@ -137,6 +176,10 @@ static int mem_event_callback(struct notifier_block *self,
if (aop_send_msg(__pfn_to_phys(start), true))
pr_err("PASR: AOP online request addr:0x%llx failed\n",
__pfn_to_phys(start));
if (!debug_pagealloc_enabled()) {
/* Create kernel page-tables */
create_pgtable_mapping(start_addr, end_addr);
}
break;
case MEM_ONLINE:
@@ -154,6 +197,10 @@ static int mem_event_callback(struct notifier_block *self,
cur = ktime_get();
break;
case MEM_OFFLINE:
if (!debug_pagealloc_enabled()) {
/* Clear kernel page-tables */
clear_pgtable_mapping(start_addr, end_addr);
}
if (aop_send_msg(__pfn_to_phys(start), false))
pr_err("PASR: AOP offline request addr:0x%llx failed\n",
__pfn_to_phys(start));

2
include/linux/memblock.h
View File

@@ -140,7 +140,7 @@ void __next_reserved_mem_region(u64 *idx, phys_addr_t *out_start,
void __memblock_free_early(phys_addr_t base, phys_addr_t size);
void __memblock_free_late(phys_addr_t base, phys_addr_t size);
void create_pgtable_mapping(phys_addr_t start, phys_addr_t end);
/**
* for_each_mem_range - iterate through memblock areas from type_a and not
* included in type_b. Or just type_a if type_b is NULL.