Commit 91bb3082 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/32s: Refactor update of user segment registers 



KUEP implements the update of user segment registers.

Move it into mmu-hash.h in order to use it from other places.

And inline kuep_lock() and kuep_unlock(). Inlining kuep_lock() is
important for system_call_exception(), otherwise system_call_exception()
has to save into stack the system call parameters that are used just
after, and doing that takes more instructions than kuep_lock() itself.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/24591ca480d14a62ef910e38a5273d551262c4a2.1622708530.git.christophe.leroy@csgroup.eu
parent 91ec6671

arch/powerpc/include/asm/book3s/32/kup.h

+21 −0
Original line number Diff line number Diff line
@@ -7,6 +7,27 @@ 


#ifndef __ASSEMBLY__



static __always_inline bool kuep_is_disabled(void)

{

	return !IS_ENABLED(CONFIG_PPC_KUEP);

}



static inline void kuep_lock(void)

{

	if (kuep_is_disabled())

		return;



	update_user_segments(mfsr(0) | SR_NX);

}



static inline void kuep_unlock(void)

{

	if (kuep_is_disabled())

		return;



	update_user_segments(mfsr(0) & ~SR_NX);

}



#ifdef CONFIG_PPC_KUAP



#include <linux/sched.h>

arch/powerpc/include/asm/book3s/32/mmu-hash.h

+27 −0
Original line number Diff line number Diff line
@@ -102,6 +102,33 @@ extern s32 patch__hash_page_B, patch__hash_page_C; 
extern s32 patch__flush_hash_A0, patch__flush_hash_A1, patch__flush_hash_A2;

extern s32 patch__flush_hash_B;



#include <asm/reg.h>

#include <asm/task_size_32.h>



#define UPDATE_TWO_USER_SEGMENTS(n) do {		\

	if (TASK_SIZE > ((n) << 28))			\

		mtsr(val1, (n) << 28);			\

	if (TASK_SIZE > (((n) + 1) << 28))		\

		mtsr(val2, ((n) + 1) << 28);		\

	val1 = (val1 + 0x222) & 0xf0ffffff;		\

	val2 = (val2 + 0x222) & 0xf0ffffff;		\

} while (0)



static __always_inline void update_user_segments(u32 val)

{

	int val1 = val;

	int val2 = (val + 0x111) & 0xf0ffffff;



	UPDATE_TWO_USER_SEGMENTS(0);

	UPDATE_TWO_USER_SEGMENTS(2);

	UPDATE_TWO_USER_SEGMENTS(4);

	UPDATE_TWO_USER_SEGMENTS(6);

	UPDATE_TWO_USER_SEGMENTS(8);

	UPDATE_TWO_USER_SEGMENTS(10);

	UPDATE_TWO_USER_SEGMENTS(12);

	UPDATE_TWO_USER_SEGMENTS(14);

}



#endif /* !__ASSEMBLY__ */



/* We happily ignore the smaller BATs on 601, we don't actually use

arch/powerpc/include/asm/kup.h

+1 −4
Original line number Diff line number Diff line
@@ -46,10 +46,7 @@ void setup_kuep(bool disabled); 
static inline void setup_kuep(bool disabled) { }

#endif /* CONFIG_PPC_KUEP */



#if defined(CONFIG_PPC_KUEP) && defined(CONFIG_PPC_BOOK3S_32)

void kuep_lock(void);

void kuep_unlock(void);

#else

#ifndef CONFIG_PPC_BOOK3S_32

static inline void kuep_lock(void) { }

static inline void kuep_unlock(void) { }

#endif

arch/powerpc/mm/book3s32/kuep.c

+0 −37
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-or-later



#include <asm/kup.h>

#include <asm/reg.h>

#include <asm/task_size_32.h>

#include <asm/mmu.h>



#define KUEP_UPDATE_TWO_USER_SEGMENTS(n) do {		\

	if (TASK_SIZE > ((n) << 28))			\

		mtsr(val1, (n) << 28);			\

	if (TASK_SIZE > (((n) + 1) << 28))		\

		mtsr(val2, ((n) + 1) << 28);		\

	val1 = (val1 + 0x222) & 0xf0ffffff;		\

	val2 = (val2 + 0x222) & 0xf0ffffff;		\

} while (0)



static __always_inline void kuep_update(u32 val)

{

	int val1 = val;

	int val2 = (val + 0x111) & 0xf0ffffff;



	KUEP_UPDATE_TWO_USER_SEGMENTS(0);

	KUEP_UPDATE_TWO_USER_SEGMENTS(2);

	KUEP_UPDATE_TWO_USER_SEGMENTS(4);

	KUEP_UPDATE_TWO_USER_SEGMENTS(6);

	KUEP_UPDATE_TWO_USER_SEGMENTS(8);

	KUEP_UPDATE_TWO_USER_SEGMENTS(10);

	KUEP_UPDATE_TWO_USER_SEGMENTS(12);

	KUEP_UPDATE_TWO_USER_SEGMENTS(14);

}



void kuep_lock(void)

{

	kuep_update(mfsr(0) | SR_NX);

}



void kuep_unlock(void)

{

	kuep_update(mfsr(0) & ~SR_NX);

}



void __init setup_kuep(bool disabled)

{