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-rw-r--r--arch/x86/include/asm/pgtable.h3
-rw-r--r--arch/x86/include/asm/text-patching.h2
-rw-r--r--arch/x86/kernel/alternative.c3
-rw-r--r--arch/x86/mm/init.c37
-rw-r--r--init/main.c3
5 files changed, 48 insertions, 0 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 2779ace16d23..702db5904753 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1021,6 +1021,9 @@ static inline void __meminit init_trampoline_default(void)
/* Default trampoline pgd value */
trampoline_pgd_entry = init_top_pgt[pgd_index(__PAGE_OFFSET)];
}
+
+void __init poking_init(void);
+
# ifdef CONFIG_RANDOMIZE_MEMORY
void __meminit init_trampoline(void);
# else
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index f8fc8e86cf01..a75eed841eed 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -39,5 +39,7 @@ extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len);
extern int poke_int3_handler(struct pt_regs *regs);
extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);
extern int after_bootmem;
+extern __ro_after_init struct mm_struct *poking_mm;
+extern __ro_after_init unsigned long poking_addr;
#endif /* _ASM_X86_TEXT_PATCHING_H */
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 0a814d73547a..11d5c710a94f 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -679,6 +679,9 @@ void *__init_or_module text_poke_early(void *addr, const void *opcode,
return addr;
}
+__ro_after_init struct mm_struct *poking_mm;
+__ro_after_init unsigned long poking_addr;
+
static void *__text_poke(void *addr, const void *opcode, size_t len)
{
unsigned long flags;
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 8dacdb96899e..fd10d91a6115 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -6,6 +6,7 @@
#include <linux/swapfile.h>
#include <linux/swapops.h>
#include <linux/kmemleak.h>
+#include <linux/sched/task.h>
#include <asm/set_memory.h>
#include <asm/e820/api.h>
@@ -23,6 +24,7 @@
#include <asm/hypervisor.h>
#include <asm/cpufeature.h>
#include <asm/pti.h>
+#include <asm/text-patching.h>
/*
* We need to define the tracepoints somewhere, and tlb.c
@@ -702,6 +704,41 @@ void __init init_mem_mapping(void)
}
/*
+ * Initialize an mm_struct to be used during poking and a pointer to be used
+ * during patching.
+ */
+void __init poking_init(void)
+{
+ spinlock_t *ptl;
+ pte_t *ptep;
+
+ poking_mm = copy_init_mm();
+ BUG_ON(!poking_mm);
+
+ /*
+ * Randomize the poking address, but make sure that the following page
+ * will be mapped at the same PMD. We need 2 pages, so find space for 3,
+ * and adjust the address if the PMD ends after the first one.
+ */
+ poking_addr = TASK_UNMAPPED_BASE;
+ if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
+ poking_addr += (kaslr_get_random_long("Poking") & PAGE_MASK) %
+ (TASK_SIZE - TASK_UNMAPPED_BASE - 3 * PAGE_SIZE);
+
+ if (((poking_addr + PAGE_SIZE) & ~PMD_MASK) == 0)
+ poking_addr += PAGE_SIZE;
+
+ /*
+ * We need to trigger the allocation of the page-tables that will be
+ * needed for poking now. Later, poking may be performed in an atomic
+ * section, which might cause allocation to fail.
+ */
+ ptep = get_locked_pte(poking_mm, poking_addr, &ptl);
+ BUG_ON(!ptep);
+ pte_unmap_unlock(ptep, ptl);
+}
+
+/*
* devmem_is_allowed() checks to see if /dev/mem access to a certain address
* is valid. The argument is a physical page number.
*
diff --git a/init/main.c b/init/main.c
index 7d4025d665eb..95dd9406ee31 100644
--- a/init/main.c
+++ b/init/main.c
@@ -504,6 +504,8 @@ void __init __weak thread_stack_cache_init(void)
void __init __weak mem_encrypt_init(void) { }
+void __init __weak poking_init(void) { }
+
bool initcall_debug;
core_param(initcall_debug, initcall_debug, bool, 0644);
@@ -737,6 +739,7 @@ asmlinkage __visible void __init start_kernel(void)
taskstats_init_early();
delayacct_init();
+ poking_init();
check_bugs();
acpi_subsystem_init();