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-rw-r--r--arch/powerpc/kernel/optprobes_head.S136
1 files changed, 136 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S
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+++ b/arch/powerpc/kernel/optprobes_head.S
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+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Code to prepare detour buffer for optprobes in Kernel.
+ *
+ * Copyright 2017, Anju T, IBM Corp.
+ */
+
+#include <asm/ppc_asm.h>
+#include <asm/ptrace.h>
+#include <asm/asm-offsets.h>
+
+#ifdef CONFIG_PPC64
+#define SAVE_30GPRS(base) SAVE_GPRS(2, 31, base)
+#define REST_30GPRS(base) REST_GPRS(2, 31, base)
+#define TEMPLATE_FOR_IMM_LOAD_INSNS nop; nop; nop; nop; nop
+#else
+#define SAVE_30GPRS(base) stmw r2, GPR2(base)
+#define REST_30GPRS(base) lmw r2, GPR2(base)
+#define TEMPLATE_FOR_IMM_LOAD_INSNS nop; nop; nop
+#endif
+
+#define OPT_SLOT_SIZE 65536
+
+ .balign 4
+
+ /*
+ * Reserve an area to allocate slots for detour buffer.
+ * This is part of .text section (rather than vmalloc area)
+ * as this needs to be within 32MB of the probed address.
+ */
+ .global optinsn_slot
+optinsn_slot:
+ .space OPT_SLOT_SIZE
+
+ /*
+ * Optprobe template:
+ * This template gets copied into one of the slots in optinsn_slot
+ * and gets fixed up with real optprobe structures et al.
+ */
+ .global optprobe_template_entry
+optprobe_template_entry:
+ /* Create an in-memory pt_regs */
+ PPC_STLU r1,-INT_FRAME_SIZE(r1)
+ SAVE_GPR(0,r1)
+ /* Save the previous SP into stack */
+ addi r0,r1,INT_FRAME_SIZE
+ PPC_STL r0,GPR1(r1)
+ SAVE_30GPRS(r1)
+ /* Save SPRS */
+ mfmsr r5
+ PPC_STL r5,_MSR(r1)
+ li r5,0x700
+ PPC_STL r5,_TRAP(r1)
+ li r5,0
+ PPC_STL r5,ORIG_GPR3(r1)
+ PPC_STL r5,RESULT(r1)
+ mfctr r5
+ PPC_STL r5,_CTR(r1)
+ mflr r5
+ PPC_STL r5,_LINK(r1)
+ mfspr r5,SPRN_XER
+ PPC_STL r5,_XER(r1)
+ mfcr r5
+ PPC_STL r5,_CCR(r1)
+#ifdef CONFIG_PPC64
+ lbz r5,PACAIRQSOFTMASK(r13)
+ std r5,SOFTE(r1)
+#endif
+
+ /*
+ * We may get here from a module, so load the kernel TOC in r2.
+ * The original TOC gets restored when pt_regs is restored
+ * further below.
+ */
+#ifdef CONFIG_PPC64
+ LOAD_PACA_TOC()
+#endif
+
+ .global optprobe_template_op_address
+optprobe_template_op_address:
+ /*
+ * Parameters to optimized_callback():
+ * 1. optimized_kprobe structure in r3
+ */
+ TEMPLATE_FOR_IMM_LOAD_INSNS
+
+ /* 2. pt_regs pointer in r4 */
+ addi r4,r1,STACK_INT_FRAME_REGS
+
+ .global optprobe_template_call_handler
+optprobe_template_call_handler:
+ /* Branch to optimized_callback() */
+ nop
+
+ /*
+ * Parameters for instruction emulation:
+ * 1. Pass SP in register r3.
+ */
+ addi r3,r1,STACK_INT_FRAME_REGS
+
+ .global optprobe_template_insn
+optprobe_template_insn:
+ /* 2, Pass instruction to be emulated in r4 */
+ TEMPLATE_FOR_IMM_LOAD_INSNS
+
+ .global optprobe_template_call_emulate
+optprobe_template_call_emulate:
+ /* Branch to emulate_step() */
+ nop
+
+ /*
+ * All done.
+ * Now, restore the registers...
+ */
+ PPC_LL r5,_MSR(r1)
+ mtmsr r5
+ PPC_LL r5,_CTR(r1)
+ mtctr r5
+ PPC_LL r5,_LINK(r1)
+ mtlr r5
+ PPC_LL r5,_XER(r1)
+ mtxer r5
+ PPC_LL r5,_CCR(r1)
+ mtcr r5
+ REST_GPR(0,r1)
+ REST_30GPRS(r1)
+ /* Restore the previous SP */
+ addi r1,r1,INT_FRAME_SIZE
+
+ .global optprobe_template_ret
+optprobe_template_ret:
+ /* ... and jump back from trampoline */
+ nop
+
+ .global optprobe_template_end
+optprobe_template_end: