Commit 0bc40e54 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 mm updates from Ingo Molnar:
 "The changes in here are:

   - text_poke() fixes and an extensive set of executability lockdowns,
     to (hopefully) eliminate the last residual circumstances under
     which we are using W|X mappings even temporarily on x86 kernels.
     This required a broad range of surgery in text patching facilities,
     module loading, trampoline handling and other bits.

   - tweak page fault messages to be more informative and more
     structured.

   - remove DISCONTIGMEM support on x86-32 and make SPARSEMEM the
     default.

   - reduce KASLR granularity on 5-level paging kernels from 512 GB to
     1 GB.

   - misc other changes and updates"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
  x86/mm: Initialize PGD cache during mm initialization
  x86/alternatives: Add comment about module removal races
  x86/kprobes: Use vmalloc special flag
  x86/ftrace: Use vmalloc special flag
  bpf: Use vmalloc special flag
  modules: Use vmalloc special flag
  mm/vmalloc: Add flag for freeing of special permsissions
  mm/hibernation: Make hibernation handle unmapped pages
  x86/mm/cpa: Add set_direct_map_*() functions
  x86/alternatives: Remove the return value of text_poke_*()
  x86/jump-label: Remove support for custom text poker
  x86/modules: Avoid breaking W^X while loading modules
  x86/kprobes: Set instruction page as executable
  x86/ftrace: Set trampoline pages as executable
  x86/kgdb: Avoid redundant comparison of patched code
  x86/alternatives: Use temporary mm for text poking
  x86/alternatives: Initialize temporary mm for patching
  fork: Provide a function for copying init_mm
  uprobes: Initialize uprobes earlier
  x86/mm: Save debug registers when loading a temporary mm
  ...
parents e913c4a4 caa84136

Documentation/x86/x86_64/mm.txt

+3 −3
Original line number Diff line number Diff line
@@ -72,7 +72,7 @@ Complete virtual memory map with 5-level page tables 
Notes:



 - With 56-bit addresses, user-space memory gets expanded by a factor of 512x,

   from 0.125 PB to 64 PB. All kernel mappings shift down to the -64 PT starting

   from 0.125 PB to 64 PB. All kernel mappings shift down to the -64 PB starting

   offset and many of the regions expand to support the much larger physical

   memory supported.
@@ -83,7 +83,7 @@ Notes: 
 0000000000000000 |    0       | 00ffffffffffffff |   64 PB | user-space virtual memory, different per mm

__________________|____________|__________________|_________|___________________________________________________________

                  |            |                  |         |

 0000800000000000 |  +64    PB | ffff7fffffffffff | ~16K PB | ... huge, still almost 64 bits wide hole of non-canonical

 0100000000000000 |  +64    PB | feffffffffffffff | ~16K PB | ... huge, still almost 64 bits wide hole of non-canonical

                  |            |                  |         |     virtual memory addresses up to the -64 PB

                  |            |                  |         |     starting offset of kernel mappings.

__________________|____________|__________________|_________|___________________________________________________________
@@ -99,7 +99,7 @@ ____________________________________________________________|___________________ 
 ffd2000000000000 |  -11.5  PB | ffd3ffffffffffff |  0.5 PB | ... unused hole

 ffd4000000000000 |  -11    PB | ffd5ffffffffffff |  0.5 PB | virtual memory map (vmemmap_base)

 ffd6000000000000 |  -10.5  PB | ffdeffffffffffff | 2.25 PB | ... unused hole

 ffdf000000000000 |   -8.25 PB | fffffdffffffffff |   ~8 PB | KASAN shadow memory

 ffdf000000000000 |   -8.25 PB | fffffbffffffffff |   ~8 PB | KASAN shadow memory

__________________|____________|__________________|_________|____________________________________________________________

                                                            |

                                                            | Identical layout to the 47-bit one from here on:

arch/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -249,6 +249,10 @@ config ARCH_HAS_FORTIFY_SOURCE 
config ARCH_HAS_SET_MEMORY

	bool



# Select if arch has all set_direct_map_invalid/default() functions

config ARCH_HAS_SET_DIRECT_MAP

	bool



# Select if arch init_task must go in the __init_task_data section

config ARCH_TASK_STRUCT_ON_STACK

       bool

arch/x86/Kconfig

+4 −7
Original line number Diff line number Diff line
@@ -65,6 +65,7 @@ config X86 
	select ARCH_HAS_UACCESS_FLUSHCACHE	if X86_64

	select ARCH_HAS_UACCESS_MCSAFE		if X86_64 && X86_MCE

	select ARCH_HAS_SET_MEMORY

	select ARCH_HAS_SET_DIRECT_MAP

	select ARCH_HAS_STRICT_KERNEL_RWX

	select ARCH_HAS_STRICT_MODULE_RWX

	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
@@ -1592,12 +1593,9 @@ config ARCH_FLATMEM_ENABLE 
	depends on X86_32 && !NUMA



config ARCH_DISCONTIGMEM_ENABLE

	def_bool y

	depends on NUMA && X86_32



config ARCH_DISCONTIGMEM_DEFAULT

	def_bool y

	def_bool n

	depends on NUMA && X86_32

	depends on BROKEN



config ARCH_SPARSEMEM_ENABLE

	def_bool y
@@ -1606,8 +1604,7 @@ config ARCH_SPARSEMEM_ENABLE 
	select SPARSEMEM_VMEMMAP_ENABLE if X86_64



config ARCH_SPARSEMEM_DEFAULT

	def_bool y

	depends on X86_64

	def_bool X86_64 || (NUMA && X86_32)



config ARCH_SELECT_MEMORY_MODEL

	def_bool y

arch/x86/include/asm/fixmap.h

+0 −2
Original line number Diff line number Diff line
@@ -103,8 +103,6 @@ enum fixed_addresses { 
#ifdef CONFIG_PARAVIRT

	FIX_PARAVIRT_BOOTMAP,

#endif

	FIX_TEXT_POKE1,	/* reserve 2 pages for text_poke() */

	FIX_TEXT_POKE0, /* first page is last, because allocation is backward */

#ifdef	CONFIG_X86_INTEL_MID

	FIX_LNW_VRTC,

#endif

arch/x86/include/asm/mmu_context.h

+56 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <asm/tlbflush.h>

#include <asm/paravirt.h>

#include <asm/mpx.h>

#include <asm/debugreg.h>



extern atomic64_t last_mm_ctx_id;
@@ -356,4 +357,59 @@ static inline unsigned long __get_current_cr3_fast(void) 
	return cr3;

}



typedef struct {

	struct mm_struct *mm;

} temp_mm_state_t;



/*

 * Using a temporary mm allows to set temporary mappings that are not accessible

 * by other CPUs. Such mappings are needed to perform sensitive memory writes

 * that override the kernel memory protections (e.g., W^X), without exposing the

 * temporary page-table mappings that are required for these write operations to

 * other CPUs. Using a temporary mm also allows to avoid TLB shootdowns when the

 * mapping is torn down.

 *

 * Context: The temporary mm needs to be used exclusively by a single core. To

 *          harden security IRQs must be disabled while the temporary mm is

 *          loaded, thereby preventing interrupt handler bugs from overriding

 *          the kernel memory protection.

 */

static inline temp_mm_state_t use_temporary_mm(struct mm_struct *mm)

{

	temp_mm_state_t temp_state;



	lockdep_assert_irqs_disabled();

	temp_state.mm = this_cpu_read(cpu_tlbstate.loaded_mm);

	switch_mm_irqs_off(NULL, mm, current);



	/*

	 * If breakpoints are enabled, disable them while the temporary mm is

	 * used. Userspace might set up watchpoints on addresses that are used

	 * in the temporary mm, which would lead to wrong signals being sent or

	 * crashes.

	 *

	 * Note that breakpoints are not disabled selectively, which also causes

	 * kernel breakpoints (e.g., perf's) to be disabled. This might be

	 * undesirable, but still seems reasonable as the code that runs in the

	 * temporary mm should be short.

	 */

	if (hw_breakpoint_active())

		hw_breakpoint_disable();



	return temp_state;

}



static inline void unuse_temporary_mm(temp_mm_state_t prev_state)

{

	lockdep_assert_irqs_disabled();

	switch_mm_irqs_off(NULL, prev_state.mm, current);



	/*

	 * Restore the breakpoints if they were disabled before the temporary mm

	 * was loaded.

	 */

	if (hw_breakpoint_active())

		hw_breakpoint_restore();

}



#endif /* _ASM_X86_MMU_CONTEXT_H */

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