From 83afab4ce05660c728f4a5d45f5970d9cc9ee6d2 Mon Sep 17 00:00:00 2001 From: Ravi Bangoria Date: Mon, 21 May 2018 09:51:07 +0530 Subject: [PATCH] powerpc/sstep: Fix kernel crash if VSX is not present emulate_step() is not checking runtime VSX feature flag before emulating an instruction. This is causing kernel crash when kernel is compiled with CONFIG_VSX=y but running on a machine where VSX is not supported or disabled. Ex, while running emulate_step tests on P6 machine: Oops: Exception in kernel mode, sig: 4 [#1] NIP [c000000000095c24] .load_vsrn+0x28/0x54 LR [c000000000094bdc] .emulate_loadstore+0x167c/0x17b0 Call Trace: 0x40fe240c7ae147ae (unreliable) .emulate_loadstore+0x167c/0x17b0 .emulate_step+0x25c/0x5bc .test_lxvd2x_stxvd2x+0x64/0x154 .test_emulate_step+0x38/0x4c .do_one_initcall+0x5c/0x2c0 .kernel_init_freeable+0x314/0x4cc .kernel_init+0x24/0x160 .ret_from_kernel_thread+0x58/0xb4 With fix: emulate_step_test: lxvd2x : FAIL emulate_step_test: stxvd2x : FAIL Reported-by: Michael Ellerman Signed-off-by: Ravi Bangoria Signed-off-by: Michael Ellerman --- arch/powerpc/lib/sstep.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index f18d70449255..d81568f783e5 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -2545,6 +2545,15 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs, #endif /* __powerpc64__ */ } + +#ifdef CONFIG_VSX + if ((GETTYPE(op->type) == LOAD_VSX || + GETTYPE(op->type) == STORE_VSX) && + !cpu_has_feature(CPU_FTR_VSX)) { + return -1; + } +#endif /* CONFIG_VSX */ + return 0; logical_done: