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-rw-r--r--arch/powerpc/kernel/reloc_32.S208
1 files changed, 208 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/reloc_32.S b/arch/powerpc/kernel/reloc_32.S
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index 000000000000..ef46ba6e094f
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+++ b/arch/powerpc/kernel/reloc_32.S
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+/*
+ * Code to process dynamic relocations for PPC32.
+ *
+ * Copyrights (C) IBM Corporation, 2011.
+ * Author: Suzuki Poulose <suzuki@in.ibm.com>
+ *
+ * - Based on ppc64 code - reloc_64.S
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <asm/ppc_asm.h>
+
+/* Dynamic section table entry tags */
+DT_RELA = 7 /* Tag for Elf32_Rela section */
+DT_RELASZ = 8 /* Size of the Rela relocs */
+DT_RELAENT = 9 /* Size of one Rela reloc entry */
+
+STN_UNDEF = 0 /* Undefined symbol index */
+STB_LOCAL = 0 /* Local binding for the symbol */
+
+R_PPC_ADDR16_LO = 4 /* Lower half of (S+A) */
+R_PPC_ADDR16_HI = 5 /* Upper half of (S+A) */
+R_PPC_ADDR16_HA = 6 /* High Adjusted (S+A) */
+R_PPC_RELATIVE = 22
+
+/*
+ * r3 = desired final address
+ */
+
+_GLOBAL(relocate)
+
+ mflr r0 /* Save our LR */
+ bl 0f /* Find our current runtime address */
+0: mflr r12 /* Make it accessible */
+ mtlr r0
+
+ lwz r11, (p_dyn - 0b)(r12)
+ add r11, r11, r12 /* runtime address of .dynamic section */
+ lwz r9, (p_rela - 0b)(r12)
+ add r9, r9, r12 /* runtime address of .rela.dyn section */
+ lwz r10, (p_st - 0b)(r12)
+ add r10, r10, r12 /* runtime address of _stext section */
+ lwz r13, (p_sym - 0b)(r12)
+ add r13, r13, r12 /* runtime address of .dynsym section */
+
+ /*
+ * Scan the dynamic section for RELA, RELASZ entries
+ */
+ li r6, 0
+ li r7, 0
+ li r8, 0
+1: lwz r5, 0(r11) /* ELF_Dyn.d_tag */
+ cmpwi r5, 0 /* End of ELF_Dyn[] */
+ beq eodyn
+ cmpwi r5, DT_RELA
+ bne relasz
+ lwz r7, 4(r11) /* r7 = rela.link */
+ b skip
+relasz:
+ cmpwi r5, DT_RELASZ
+ bne relaent
+ lwz r8, 4(r11) /* r8 = Total Rela relocs size */
+ b skip
+relaent:
+ cmpwi r5, DT_RELAENT
+ bne skip
+ lwz r6, 4(r11) /* r6 = Size of one Rela reloc */
+skip:
+ addi r11, r11, 8
+ b 1b
+eodyn: /* End of Dyn Table scan */
+
+ /* Check if we have found all the entries */
+ cmpwi r7, 0
+ beq done
+ cmpwi r8, 0
+ beq done
+ cmpwi r6, 0
+ beq done
+
+
+ /*
+ * Work out the current offset from the link time address of .rela
+ * section.
+ * cur_offset[r7] = rela.run[r9] - rela.link [r7]
+ * _stext.link[r12] = _stext.run[r10] - cur_offset[r7]
+ * final_offset[r3] = _stext.final[r3] - _stext.link[r12]
+ */
+ subf r7, r7, r9 /* cur_offset */
+ subf r12, r7, r10
+ subf r3, r12, r3 /* final_offset */
+
+ subf r8, r6, r8 /* relaz -= relaent */
+ /*
+ * Scan through the .rela table and process each entry
+ * r9 - points to the current .rela table entry
+ * r13 - points to the symbol table
+ */
+
+ /*
+ * Check if we have a relocation based on symbol
+ * r5 will hold the value of the symbol.
+ */
+applyrela:
+ lwz r4, 4(r9) /* r4 = rela.r_info */
+ srwi r5, r4, 8 /* ELF32_R_SYM(r_info) */
+ cmpwi r5, STN_UNDEF /* sym == STN_UNDEF ? */
+ beq get_type /* value = 0 */
+ /* Find the value of the symbol at index(r5) */
+ slwi r5, r5, 4 /* r5 = r5 * sizeof(Elf32_Sym) */
+ add r12, r13, r5 /* r12 = &__dyn_sym[Index] */
+
+ /*
+ * GNU ld has a bug, where dynamic relocs based on
+ * STB_LOCAL symbols, the value should be assumed
+ * to be zero. - Alan Modra
+ */
+ /* XXX: Do we need to check if we are using GNU ld ? */
+ lbz r5, 12(r12) /* r5 = dyn_sym[Index].st_info */
+ extrwi r5, r5, 4, 24 /* r5 = ELF32_ST_BIND(r5) */
+ cmpwi r5, STB_LOCAL /* st_value = 0, ld bug */
+ beq get_type /* We have r5 = 0 */
+ lwz r5, 4(r12) /* r5 = __dyn_sym[Index].st_value */
+
+get_type:
+ /* Load the relocation type to r4 */
+ extrwi r4, r4, 8, 24 /* r4 = ELF32_R_TYPE(r_info) = ((char*)r4)[3] */
+
+ /* R_PPC_RELATIVE */
+ cmpwi r4, R_PPC_RELATIVE
+ bne hi16
+ lwz r4, 0(r9) /* r_offset */
+ lwz r0, 8(r9) /* r_addend */
+ add r0, r0, r3 /* final addend */
+ stwx r0, r4, r7 /* memory[r4+r7]) = (u32)r0 */
+ b nxtrela /* continue */
+
+ /* R_PPC_ADDR16_HI */
+hi16:
+ cmpwi r4, R_PPC_ADDR16_HI
+ bne ha16
+ lwz r4, 0(r9) /* r_offset */
+ lwz r0, 8(r9) /* r_addend */
+ add r0, r0, r3
+ add r0, r0, r5 /* r0 = (S+A+Offset) */
+ extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */
+ b store_half
+
+ /* R_PPC_ADDR16_HA */
+ha16:
+ cmpwi r4, R_PPC_ADDR16_HA
+ bne lo16
+ lwz r4, 0(r9) /* r_offset */
+ lwz r0, 8(r9) /* r_addend */
+ add r0, r0, r3
+ add r0, r0, r5 /* r0 = (S+A+Offset) */
+ extrwi r5, r0, 1, 16 /* Extract bit 16 */
+ extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */
+ add r0, r0, r5 /* Add it to r0 */
+ b store_half
+
+ /* R_PPC_ADDR16_LO */
+lo16:
+ cmpwi r4, R_PPC_ADDR16_LO
+ bne nxtrela
+ lwz r4, 0(r9) /* r_offset */
+ lwz r0, 8(r9) /* r_addend */
+ add r0, r0, r3
+ add r0, r0, r5 /* r0 = (S+A+Offset) */
+ extrwi r0, r0, 16, 16 /* r0 &= 0xffff */
+ /* Fall through to */
+
+ /* Store half word */
+store_half:
+ sthx r0, r4, r7 /* memory[r4+r7] = (u16)r0 */
+
+nxtrela:
+ /*
+ * We have to flush the modified instructions to the
+ * main storage from the d-cache. And also, invalidate the
+ * cached instructions in i-cache which has been modified.
+ *
+ * We delay the sync / isync operation till the end, since
+ * we won't be executing the modified instructions until
+ * we return from here.
+ */
+ dcbst r4,r7
+ sync /* Ensure the data is flushed before icbi */
+ icbi r4,r7
+ cmpwi r8, 0 /* relasz = 0 ? */
+ ble done
+ add r9, r9, r6 /* move to next entry in the .rela table */
+ subf r8, r6, r8 /* relasz -= relaent */
+ b applyrela
+
+done:
+ sync /* Wait for the flush to finish */
+ isync /* Discard prefetched instructions */
+ blr
+
+p_dyn: .long __dynamic_start - 0b
+p_rela: .long __rela_dyn_start - 0b
+p_sym: .long __dynamic_symtab - 0b
+p_st: .long _stext - 0b

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