Commit f5b5ea51 authored by Joey Gouly's avatar Joey Gouly Committed by Will Deacon
Browse files

selftests: mm: make protection_keys test work on arm64 



The encoding of the pkey register differs on arm64, than on x86/ppc. On those
platforms, a bit in the register is used to disable permissions, for arm64, a
bit enabled in the register indicates that the permission is allowed.

This drops two asserts of the form:
	 assert(read_pkey_reg() <= orig_pkey_reg);
Because on arm64 this doesn't hold, due to the encoding.

The pkey must be reset to both access allow and write allow in the signal
handler. pkey_access_allow() works currently for PowerPC as the
PKEY_DISABLE_ACCESS and PKEY_DISABLE_WRITE have overlapping bits set.

Access to the uc_mcontext is abstracted, as arm64 has a different structure.

Signed-off-by: default avatarJoey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Acked-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20240822151113.1479789-27-joey.gouly@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 41bbcf7b

tools/testing/selftests/arm64/signal/testcases/testcases.h

+3 −0
Original line number Diff line number Diff line
@@ -26,6 +26,9 @@ 
#define HDR_SZ \

	sizeof(struct _aarch64_ctx)



#define GET_UC_RESV_HEAD(uc) \

	(struct _aarch64_ctx *)(&(uc->uc_mcontext.__reserved))



#define GET_SF_RESV_HEAD(sf) \

	(struct _aarch64_ctx *)(&(sf).uc.uc_mcontext.__reserved)

tools/testing/selftests/mm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -104,7 +104,7 @@ TEST_GEN_FILES += $(BINARIES_64) 
endif

else



ifneq (,$(findstring $(ARCH),powerpc))

ifneq (,$(filter $(ARCH),arm64 powerpc))

TEST_GEN_FILES += protection_keys

endif

tools/testing/selftests/mm/pkey-arm64.h

0 → 100644
+139 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * Copyright (C) 2023 Arm Ltd.

 */



#ifndef _PKEYS_ARM64_H

#define _PKEYS_ARM64_H



#include "vm_util.h"

/* for signal frame parsing */

#include "../arm64/signal/testcases/testcases.h"



#ifndef SYS_mprotect_key

# define SYS_mprotect_key	288

#endif

#ifndef SYS_pkey_alloc

# define SYS_pkey_alloc		289

# define SYS_pkey_free		290

#endif

#define MCONTEXT_IP(mc)		mc.pc

#define MCONTEXT_TRAPNO(mc)	-1



#define PKEY_MASK		0xf



#define POE_NONE		0x0

#define POE_X			0x2

#define POE_RX			0x3

#define POE_RWX			0x7



#define NR_PKEYS		8

#define NR_RESERVED_PKEYS	1 /* pkey-0 */



#define PKEY_ALLOW_ALL		0x77777777



#define PKEY_BITS_PER_PKEY	4

#define PAGE_SIZE		sysconf(_SC_PAGESIZE)

#undef HPAGE_SIZE

#define HPAGE_SIZE		default_huge_page_size()



/* 4-byte instructions * 16384 = 64K page */

#define __page_o_noops() asm(".rept 16384 ; nop; .endr")



static inline u64 __read_pkey_reg(void)

{

	u64 pkey_reg = 0;



	// POR_EL0

	asm volatile("mrs %0, S3_3_c10_c2_4" : "=r" (pkey_reg));



	return pkey_reg;

}



static inline void __write_pkey_reg(u64 pkey_reg)

{

	u64 por = pkey_reg;



	dprintf4("%s() changing %016llx to %016llx\n",

			 __func__, __read_pkey_reg(), pkey_reg);



	// POR_EL0

	asm volatile("msr S3_3_c10_c2_4, %0\nisb" :: "r" (por) :);



	dprintf4("%s() pkey register after changing %016llx to %016llx\n",

			__func__, __read_pkey_reg(), pkey_reg);

}



static inline int cpu_has_pkeys(void)

{

	/* No simple way to determine this */

	return 1;

}



static inline u32 pkey_bit_position(int pkey)

{

	return pkey * PKEY_BITS_PER_PKEY;

}



static inline int get_arch_reserved_keys(void)

{

	return NR_RESERVED_PKEYS;

}



void expect_fault_on_read_execonly_key(void *p1, int pkey)

{

}



void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)

{

	return PTR_ERR_ENOTSUP;

}



#define set_pkey_bits	set_pkey_bits

static inline u64 set_pkey_bits(u64 reg, int pkey, u64 flags)

{

	u32 shift = pkey_bit_position(pkey);

	u64 new_val = POE_RWX;



	/* mask out bits from pkey in old value */

	reg &= ~((u64)PKEY_MASK << shift);



	if (flags & PKEY_DISABLE_ACCESS)

		new_val = POE_X;

	else if (flags & PKEY_DISABLE_WRITE)

		new_val = POE_RX;



	/* OR in new bits for pkey */

	reg |= new_val << shift;



	return reg;

}



#define get_pkey_bits	get_pkey_bits

static inline u64 get_pkey_bits(u64 reg, int pkey)

{

	u32 shift = pkey_bit_position(pkey);

	/*

	 * shift down the relevant bits to the lowest four, then

	 * mask off all the other higher bits

	 */

	u32 perm = (reg >> shift) & PKEY_MASK;



	if (perm == POE_X)

		return PKEY_DISABLE_ACCESS;

	if (perm == POE_RX)

		return PKEY_DISABLE_WRITE;

	return 0;

}



static void aarch64_write_signal_pkey(ucontext_t *uctxt, u64 pkey)

{

	struct _aarch64_ctx *ctx = GET_UC_RESV_HEAD(uctxt);

	struct poe_context *poe_ctx =

		(struct poe_context *) get_header(ctx, POE_MAGIC,

						sizeof(uctxt->uc_mcontext), NULL);

	if (poe_ctx)

		poe_ctx->por_el0 = pkey;

}



#endif /* _PKEYS_ARM64_H */

tools/testing/selftests/mm/pkey-helpers.h

+8 −0
Original line number Diff line number Diff line
@@ -91,12 +91,17 @@ void record_pkey_malloc(void *ptr, long size, int prot); 
#include "pkey-x86.h"

#elif defined(__powerpc64__) /* arch */

#include "pkey-powerpc.h"

#elif defined(__aarch64__) /* arch */

#include "pkey-arm64.h"

#else /* arch */

#error Architecture not supported

#endif /* arch */



#ifndef PKEY_MASK

#define PKEY_MASK	(PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE)

#endif



#ifndef set_pkey_bits

static inline u64 set_pkey_bits(u64 reg, int pkey, u64 flags)

{

	u32 shift = pkey_bit_position(pkey);
@@ -106,7 +111,9 @@ static inline u64 set_pkey_bits(u64 reg, int pkey, u64 flags) 
	reg |= (flags & PKEY_MASK) << shift;

	return reg;

}

#endif



#ifndef get_pkey_bits

static inline u64 get_pkey_bits(u64 reg, int pkey)

{

	u32 shift = pkey_bit_position(pkey);
@@ -116,6 +123,7 @@ static inline u64 get_pkey_bits(u64 reg, int pkey) 
	 */

	return ((reg >> shift) & PKEY_MASK);

}

#endif



extern u64 shadow_pkey_reg;

tools/testing/selftests/mm/pkey-powerpc.h

+2 −0
Original line number Diff line number Diff line
@@ -8,6 +8,8 @@ 
# define SYS_pkey_free		385

#endif

#define REG_IP_IDX		PT_NIP

#define MCONTEXT_IP(mc)		mc.gp_regs[REG_IP_IDX]

#define MCONTEXT_TRAPNO(mc)	mc.gp_regs[REG_TRAPNO]

#define REG_TRAPNO		PT_TRAP

#define MCONTEXT_FPREGS

#define gregs			gp_regs