So far the RELACOUNT tag from the ELF header was containing the exact number of R_PPC_RELATIVE/R_PPC64_RELATIVE relocations. However the LLVM's recent change [1] make it equal-or-less than the actual number which makes it useless.
This replaces RELACOUNT in zImage loader with a pair of RELASZ and RELAENT. The vmlinux relocation code is fixed in [2]. To make it more future proof, this walks through the entire .rela.dyn section instead of assuming that the section is sorter by a relocation type. Unlike [1], this does not add unaligned UADDR/UADDR64 relocations as in hardly possible to see those in arch-specific zImage. [1] https://github.com/llvm/llvm-project/commit/da0e5b885b25cf4 [2] https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=next&id=d799769188529a Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> --- arch/powerpc/boot/crt0.S | 43 +++++++++++++++++++++++++--------------- 1 file changed, 27 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S index feadee18e271..6ea3417da3b7 100644 --- a/arch/powerpc/boot/crt0.S +++ b/arch/powerpc/boot/crt0.S @@ -8,7 +8,8 @@ #include "ppc_asm.h" RELA = 7 -RELACOUNT = 0x6ffffff9 +RELASZ = 8 +RELAENT = 9 .data /* A procedure descriptor used when booting this as a COFF file. @@ -75,34 +76,38 @@ p_base: mflr r10 /* r10 now points to runtime addr of p_base */ bne 11f lwz r9,4(r12) /* get RELA pointer in r9 */ b 12f -11: addis r8,r8,(-RELACOUNT)@ha - cmpwi r8,RELACOUNT@l +11: cmpwi r8,RELASZ + bne 111f + lwz r0,4(r12) /* get RELASZ value in r0 */ + b 12f +111: cmpwi r8,RELAENT bne 12f - lwz r0,4(r12) /* get RELACOUNT value in r0 */ + lwz r14,4(r12) /* get RELAENT value in r14 */ 12: addi r12,r12,8 b 9b /* The relocation section contains a list of relocations. * We now do the R_PPC_RELATIVE ones, which point to words - * which need to be initialized with addend + offset. - * The R_PPC_RELATIVE ones come first and there are RELACOUNT - * of them. */ + * which need to be initialized with addend + offset */ 10: /* skip relocation if we don't have both */ cmpwi r0,0 beq 3f cmpwi r9,0 beq 3f + cmpwi r14,0 + beq 3f add r9,r9,r11 /* Relocate RELA pointer */ + divd r0,r0,r14 /* RELASZ / RELAENT */ mtctr r0 2: lbz r0,4+3(r9) /* ELF32_R_INFO(reloc->r_info) */ cmpwi r0,22 /* R_PPC_RELATIVE */ - bne 3f + bne 22f lwz r12,0(r9) /* reloc->r_offset */ lwz r0,8(r9) /* reloc->r_addend */ add r0,r0,r11 stwx r0,r11,r12 - addi r9,r9,12 +22: add r9,r9,r14 bdnz 2b /* Do a cache flush for our text, in case the loader didn't */ @@ -160,32 +165,38 @@ p_base: mflr r10 /* r10 now points to runtime addr of p_base */ bne 10f ld r13,8(r11) /* get RELA pointer in r13 */ b 11f -10: addis r12,r12,(-RELACOUNT)@ha - cmpdi r12,RELACOUNT@l - bne 11f - ld r8,8(r11) /* get RELACOUNT value in r8 */ +10: cmpwi r12,RELASZ + bne 101f + lwz r8,8(r11) /* get RELASZ pointer in r8 */ + b 11f +101: cmpwi r12,RELAENT + bne 11f + lwz r14,8(r11) /* get RELAENT pointer in r14 */ 11: addi r11,r11,16 b 9b 12: - cmpdi r13,0 /* check we have both RELA and RELACOUNT */ + cmpdi r13,0 /* check we have both RELA, RELASZ, RELAENT*/ cmpdi cr1,r8,0 beq 3f beq cr1,3f + cmpdi r14,0 + beq 3f /* Calcuate the runtime offset. */ subf r13,r13,r9 /* Run through the list of relocations and process the * R_PPC64_RELATIVE ones. */ + divd r8,r8,r14 /* RELASZ / RELAENT */ mtctr r8 13: ld r0,8(r9) /* ELF64_R_TYPE(reloc->r_info) */ cmpdi r0,22 /* R_PPC64_RELATIVE */ - bne 3f + bne 14f ld r12,0(r9) /* reloc->r_offset */ ld r0,16(r9) /* reloc->r_addend */ add r0,r0,r13 stdx r0,r13,r12 - addi r9,r9,24 +14: add r9,r9,r14 bdnz 13b /* Do a cache flush for our text, in case the loader didn't */ -- 2.30.2
