Commit 70428da9 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/32s: Save content of sr0 to avoid 'mfsr' 



Calling 'mfsr' to get the content of segment registers is heavy,
in addition it requires clearing of the 'reserved' bits.

In order to avoid this operation, save it in mm context and in
thread struct.

The saved sr0 is the one used by kernel, this means that on
locking entry it can be used as is.

For unlocking, the only thing to do is to clear SR_NX.

This improves null_syscall selftest by 12 cycles, ie 4%.

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/b02baf2ed8f09bad910dfaeeb7353b2ae6830525.1634627931.git.christophe.leroy@csgroup.eu
parent 526d4a4c

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

+5 −0
Original line number Diff line number Diff line
@@ -175,9 +175,14 @@ struct hash_pte { 


typedef struct {

	unsigned long id;

	unsigned long sr0;

	void __user *vdso;

} mm_context_t;



#ifdef CONFIG_PPC_KUEP

#define INIT_MM_CONTEXT(mm) .context.sr0 = SR_NX

#endif



void update_bats(void);

static inline void cleanup_cpu_mmu_context(void) { }

arch/powerpc/include/asm/processor.h

+9 −0
Original line number Diff line number Diff line
@@ -157,6 +157,7 @@ struct thread_struct { 
#ifdef CONFIG_PPC_BOOK3S_32

	unsigned long	r0, r3, r4, r5, r6, r8, r9, r11;

	unsigned long	lr, ctr;

	unsigned long	sr0;

#endif

#endif /* CONFIG_PPC32 */

	/* Debug Registers */
@@ -278,6 +279,12 @@ struct thread_struct { 
#define SPEFSCR_INIT

#endif



#ifdef CONFIG_PPC_BOOK3S_32

#define SR0_INIT	.sr0 = IS_ENABLED(CONFIG_PPC_KUEP) ? SR_NX : 0,

#else

#define SR0_INIT

#endif



#if defined(CONFIG_PPC_BOOK3S_32) && defined(CONFIG_PPC_KUAP)

#define INIT_THREAD { \

	.ksp = INIT_SP, \
@@ -285,6 +292,7 @@ struct thread_struct { 
	.kuap = ~0UL, /* KUAP_NONE */ \

	.fpexc_mode = MSR_FE0 | MSR_FE1, \

	SPEFSCR_INIT \

	SR0_INIT \

}

#elif defined(CONFIG_PPC32)

#define INIT_THREAD { \
@@ -292,6 +300,7 @@ struct thread_struct { 
	.pgdir = swapper_pg_dir, \

	.fpexc_mode = MSR_FE0 | MSR_FE1, \

	SPEFSCR_INIT \

	SR0_INIT \

}

#else

#define INIT_THREAD  { \

arch/powerpc/kernel/asm-offsets.c

+1 −0
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ int main(void) 
	OFFSET(THR11, thread_struct, r11);

	OFFSET(THLR, thread_struct, lr);

	OFFSET(THCTR, thread_struct, ctr);

	OFFSET(THSR0, thread_struct, sr0);

#endif

#ifdef CONFIG_SPE

	OFFSET(THREAD_EVR0, thread_struct, evr[0]);

arch/powerpc/kernel/entry_32.S

+3 −5
Original line number Diff line number Diff line
@@ -76,15 +76,13 @@ _ASM_NOKPROBE_SYMBOL(prepare_transfer_to_handler) 
#if defined(CONFIG_PPC_KUEP) && defined(CONFIG_PPC_BOOK3S_32)

	.globl	__kuep_lock

__kuep_lock:

	mfsr    r9,0

	rlwinm  r9,r9,0,8,3

	oris    r9,r9,SR_NX@h

	lwz	r9, THREAD+THSR0(r2)

	update_user_segments_by_4 r9, r10, r11, r12

	blr



__kuep_unlock:

	mfsr    r9,0

	rlwinm  r9,r9,0,8,2

	lwz	r9, THREAD+THSR0(r2)

	rlwinm  r9,r9,0,~SR_NX

	update_user_segments_by_4 r9, r10, r11, r12

	blr

arch/powerpc/mm/book3s32/kuap.c

+4 −1
Original line number Diff line number Diff line
@@ -20,8 +20,11 @@ EXPORT_SYMBOL(kuap_unlock_all_ool); 


void setup_kuap(bool disabled)

{

	if (!disabled)

	if (!disabled) {

		kuap_lock_all_ool();

		init_mm.context.sr0 |= SR_KS;

		current->thread.sr0 |= SR_KS;

	}



	if (smp_processor_id() != boot_cpuid)

		return;