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Subject[RFC PATCH 03/13] powerpc/dexcr: Handle hashchk exception
Date
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.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
---
arch/powerpc/include/asm/ppc-opcode.h | 1 +
arch/powerpc/include/asm/processor.h | 6 ++++++
arch/powerpc/kernel/dexcr.c | 22 ++++++++++++++++++++++
arch/powerpc/kernel/traps.c | 6 ++++++
4 files changed, 35 insertions(+)

diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 21e33e46f4b8..89b316466ed1 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -215,6 +215,7 @@
#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/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 0a8a793b8b8b..c17ec1e44c86 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -448,10 +448,16 @@ void *exit_vmx_ops(void *dest);

#ifdef CONFIG_PPC_BOOK3S_64

+bool is_hashchk_trap(struct pt_regs const *regs);
unsigned long get_thread_dexcr(struct thread_struct const *t);

#else

+static inline bool is_hashchk_trap(struct pt_regs const *regs)
+{
+ return false;
+}
+
static inline unsigned long get_thread_dexcr(struct thread_struct const *t)
{
return 0;
diff --git a/arch/powerpc/kernel/dexcr.c b/arch/powerpc/kernel/dexcr.c
index 32a0a69ff638..11515e67afac 100644
--- a/arch/powerpc/kernel/dexcr.c
+++ b/arch/powerpc/kernel/dexcr.c
@@ -3,6 +3,9 @@

#include <asm/cpu_has_feature.h>
#include <asm/cputable.h>
+#include <asm/disassemble.h>
+#include <asm/inst.h>
+#include <asm/ppc-opcode.h>
#include <asm/processor.h>
#include <asm/reg.h>

@@ -19,6 +22,25 @@ static int __init dexcr_init(void)
}
early_initcall(dexcr_init);

+bool is_hashchk_trap(struct pt_regs const *regs)
+{
+ ppc_inst_t insn;
+
+ if (!cpu_has_feature(CPU_FTR_DEXCR_NPHIE))
+ return false;
+
+ if (get_user_instr(insn, (void __user *)regs->nip)) {
+ WARN_ON(1);
+ return false;
+ }
+
+ if (ppc_inst_primary_opcode(insn) == 31 &&
+ get_xop(ppc_inst_val(insn)) == OP_31_XOP_HASHCHK)
+ return true;
+
+ return false;
+}
+
unsigned long get_thread_dexcr(struct thread_struct const *t)
{
return DEFAULT_DEXCR;
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 9bdd79aa51cf..b83f5b382f24 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1516,6 +1516,12 @@ static void do_program_check(struct pt_regs *regs)
return;
}
}
+
+ if (user_mode(regs) && is_hashchk_trap(regs)) {
+ _exception(SIGILL, regs, ILL_ILLOPN, regs->nip);
+ return;
+ }
+
_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
return;
}
--
2.38.1
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