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-rw-r--r--arch/powerpc/kernel/reloc_64.S84
1 files changed, 84 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/reloc_64.S b/arch/powerpc/kernel/reloc_64.S
new file mode 100644
index 000000000..02d4719bf
--- /dev/null
+++ b/arch/powerpc/kernel/reloc_64.S
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Code to process dynamic relocations in the kernel.
+ *
+ * Copyright 2008 Paul Mackerras, IBM Corp.
+ */
+
+#include <asm/ppc_asm.h>
+
+RELA = 7
+RELACOUNT = 0x6ffffff9
+R_PPC64_RELATIVE = 22
+
+/*
+ * r3 = desired final address of kernel
+ */
+_GLOBAL(relocate)
+ mflr r0
+ bcl 20,31,$+4
+0: mflr r12 /* r12 has runtime addr of label 0 */
+ mtlr r0
+ ld r11,(p_dyn - 0b)(r12)
+ add r11,r11,r12 /* r11 has runtime addr of .dynamic section */
+ ld r9,(p_rela - 0b)(r12)
+ add r9,r9,r12 /* r9 has runtime addr of .rela.dyn section */
+ ld r10,(p_st - 0b)(r12)
+ add r10,r10,r12 /* r10 has runtime addr of _stext */
+
+ /*
+ * Scan the dynamic section for the RELA and RELACOUNT entries.
+ */
+ li r7,0
+ li r8,0
+1: ld r6,0(r11) /* get tag */
+ cmpdi r6,0
+ beq 4f /* end of list */
+ cmpdi r6,RELA
+ bne 2f
+ ld r7,8(r11) /* get RELA pointer in r7 */
+ b 3f
+2: addis r6,r6,(-RELACOUNT)@ha
+ cmpdi r6,RELACOUNT@l
+ bne 3f
+ ld r8,8(r11) /* get RELACOUNT value in r8 */
+3: addi r11,r11,16
+ b 1b
+4: cmpdi r7,0 /* check we have both RELA and RELACOUNT */
+ cmpdi cr1,r8,0
+ beq 6f
+ beq cr1,6f
+
+ /*
+ * Work out linktime address of _stext and hence the
+ * relocation offset to be applied.
+ * cur_offset [r7] = rela.run [r9] - rela.link [r7]
+ * _stext.link [r10] = _stext.run [r10] - cur_offset [r7]
+ * final_offset [r3] = _stext.final [r3] - _stext.link [r10]
+ */
+ subf r7,r7,r9 /* cur_offset */
+ subf r10,r7,r10
+ subf r3,r10,r3 /* final_offset */
+
+ /*
+ * Run through the list of relocations and process the
+ * R_PPC64_RELATIVE ones.
+ */
+ mtctr r8
+5: ld r0,8(9) /* ELF64_R_TYPE(reloc->r_info) */
+ cmpdi r0,R_PPC64_RELATIVE
+ bne 6f
+ ld r6,0(r9) /* reloc->r_offset */
+ ld r0,16(r9) /* reloc->r_addend */
+ add r0,r0,r3
+ stdx r0,r7,r6
+ addi r9,r9,24
+ bdnz 5b
+
+6: blr
+
+.balign 8
+p_dyn: .8byte __dynamic_start - 0b
+p_rela: .8byte __rela_dyn_start - 0b
+p_st: .8byte _stext - 0b
+