Commit 29dbb984 authored by Michael Ellerman's avatar Michael Ellerman
Browse files

powerpc/64s: Remove the "fast endian switch" syscall 



The non-standard "fast endian switch" syscall was added in 2008[1],
but was never widely used. It was disabled by default in 2017[2], and
there's no evidence it's ever been used since.

Remove it entirely.

A normal endian switch syscall was added in 2015[3].

[1]: 745a14cc ("[POWERPC] Add fast little-endian switch system call")
[2]: 529d235a ("powerpc: Add a proper syscall for switching endianness")
[3]: 727f1361 ("powerpc: Disable the fast-endian switch syscall by default")

Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240823070830.1269033-1-mpe@ellerman.id.au
parent 87def77b

arch/powerpc/Kconfig.debug

+0 −6
Original line number Diff line number Diff line
@@ -379,12 +379,6 @@ config FAIL_IOMMU 


	  If you are unsure, say N.



config PPC_FAST_ENDIAN_SWITCH

	bool "Deprecated fast endian-switch syscall"

	depends on DEBUG_KERNEL && PPC_BOOK3S_64

	help

	  If you're unsure what this is, say N.



config KASAN_SHADOW_OFFSET

	hex

	depends on KASAN

arch/powerpc/kernel/exceptions-64s.S

+0 −17
Original line number Diff line number Diff line
@@ -1989,13 +1989,6 @@ INT_DEFINE_END(system_call) 
	INTERRUPT_TO_KERNEL

#endif



#ifdef CONFIG_PPC_FAST_ENDIAN_SWITCH

BEGIN_FTR_SECTION

	cmpdi	r0,0x1ebe

	beq-	1f

END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE)

#endif



	/* We reach here with PACA in r13, r13 in r9. */

	mfspr	r11,SPRN_SRR0

	mfspr	r12,SPRN_SRR1
@@ -2015,16 +2008,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) 
	b	system_call_common

#endif

	.endif



#ifdef CONFIG_PPC_FAST_ENDIAN_SWITCH

	/* Fast LE/BE switch system call */

1:	mfspr	r12,SPRN_SRR1

	xori	r12,r12,MSR_LE

	mtspr	SPRN_SRR1,r12

	mr	r13,r9

	RFI_TO_USER	/* return to userspace */

	b	.	/* prevent speculative execution */

#endif

.endm



EXC_REAL_BEGIN(system_call, 0xc00, 0x100)