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powerpc: Enable Prefixed Instructions

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Prefix instructions have their own FSCR bit which needs to enabled via
a CPU feature. The kernel will save the FSCR for problem state but it
needs to be enabled initially.

If prefixed instructions are made unavailable by the [H]FSCR, attempting
to use them will cause a facility unavailable exception. Add "PREFIX" to
the facility_strings[].

Currently there are no prefixed instructions that are actually emulated
by emulate_instruction() within facility_unavailable_exception().
However, when caused by a prefixed instructions the SRR1 PREFIXED bit is
set. Prepare for dealing with emulated prefixed instructions by checking
for this bit.

Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Link: https://lore.kernel.org/r/20200506034050.24806-22-jniethe5@gmail.com
This commit is contained in:
Alistair Popple 2020-05-06 13:40:41 +10:00 committed by Michael Ellerman
parent 0b582db549
commit 2aa6195e43
2 changed files with 4 additions and 0 deletions
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3
arch/powerpc/include/asm/reg.h
View file

@ -397,6 +397,7 @@
#define SPRN_RWMR 0x375 /* Region-Weighting Mode Register */
/* HFSCR and FSCR bit numbers are the same */
#define FSCR_PREFIX_LG 13 /* Enable Prefix Instructions */
#define FSCR_SCV_LG 12 /* Enable System Call Vectored */
#define FSCR_MSGP_LG 10 /* Enable MSGP */
#define FSCR_TAR_LG 8 /* Enable Target Address Register */
@ -408,11 +409,13 @@
#define FSCR_VECVSX_LG 1 /* Enable VMX/VSX */
#define FSCR_FP_LG 0 /* Enable Floating Point */
#define SPRN_FSCR 0x099 /* Facility Status & Control Register */
#define FSCR_PREFIX __MASK(FSCR_PREFIX_LG)
#define FSCR_SCV __MASK(FSCR_SCV_LG)
#define FSCR_TAR __MASK(FSCR_TAR_LG)
#define FSCR_EBB __MASK(FSCR_EBB_LG)
#define FSCR_DSCR __MASK(FSCR_DSCR_LG)
#define SPRN_HFSCR 0xbe /* HV=1 Facility Status & Control Register */
#define HFSCR_PREFIX __MASK(FSCR_PREFIX_LG)
#define HFSCR_MSGP __MASK(FSCR_MSGP_LG)
#define HFSCR_TAR __MASK(FSCR_TAR_LG)
#define HFSCR_EBB __MASK(FSCR_EBB_LG)

1
arch/powerpc/kernel/traps.c
View file

@ -1737,6 +1737,7 @@ void facility_unavailable_exception(struct pt_regs *regs)
[FSCR_TAR_LG] = "TAR",
[FSCR_MSGP_LG] = "MSGP",
[FSCR_SCV_LG] = "SCV",
[FSCR_PREFIX_LG] = "PREFIX",
};
char *facility = "unknown";
u64 value;