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

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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]: 745a14cc26 ("[POWERPC] Add fast little-endian switch system call")
[2]: 529d235a0e ("powerpc: Add a proper syscall for switching endianness")
[3]: 727f13616c ("powerpc: Disable the fast-endian switch syscall by default")

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240823070830.1269033-1-mpe@ellerman.id.au
This commit is contained in:
Michael Ellerman 2024-08-23 17:08:30 +10:00
parent 87def77bb5
commit 29dbb98449
2 changed files with 0 additions and 23 deletions
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6
arch/powerpc/Kconfig.debug
View File

@ -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

17
arch/powerpc/kernel/exceptions-64s.S
View File

@ -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)