Recognise and pass the appropriate signal to the user program when a
hashchk instruction triggers. This is independent of allowing
configuration of DEXCR[NPHIE], as a hypervisor can enforce this aspect
regardless of the kernel.
The signal mirrors how ARM reports their similar check failure. For
example, their FPAC handler in arch/arm64/kernel/traps.c do_el0_fpac()
does this. When we fail to read the instruction that caused the fault
we send a segfault, similar to how emulate_math() does it.
Signed-off-by: Benjamin Gray <bg...@linux.ibm.com>
---
v3: * Inline hashchk detection, remove dexcr.c and associated files
v1: * Refactor the hashchk check to return 0 on success, an error
code on failure. Determine what to do based on specific error
code.
* Motivate signal and code
---
arch/powerpc/include/asm/ppc-opcode.h | 1 +
arch/powerpc/kernel/traps.c | 16 ++++++++++++++++
2 files changed, 17 insertions(+)
diff --git a/arch/powerpc/include/asm/ppc-opcode.h
b/arch/powerpc/include/asm/ppc-opcode.h
index ca5a0da7df4e..ef6972aa33b9 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -222,6 +222,7 @@
#define OP_31_XOP_STFSX 663
#define OP_31_XOP_STFSUX 695
#define OP_31_XOP_STFDX 727
+#define OP_31_XOP_HASHCHK 754
#define OP_31_XOP_STFDUX 759
#define OP_31_XOP_LHBRX 790
#define OP_31_XOP_LFIWAX 855
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 9bdd79aa51cf..e59ec6d32d37 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1516,6 +1516,22 @@ static void do_program_check(struct pt_regs *regs)
return;
}
}
+
+ if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE) && user_mode(regs)) {
+ ppc_inst_t insn;
+
+ if (get_user_instr(insn, (void __user *)regs->nip)) {
+ _exception(SIGSEGV, regs, SEGV_MAPERR,
regs->nip);
+ return;
+ }
+
+ if (ppc_inst_primary_opcode(insn) == 31 &&
+ get_xop(ppc_inst_val(insn)) == OP_31_XOP_HASHCHK) {
+ _exception(SIGILL, regs, ILL_ILLOPN, regs->nip);
+ return;
+ }
+ }
+
_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
return;
}
--
2.40.1
