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objtool/powerpc: Add support for decoding all types of uncond branches

Add support for 'bla' instruction.

This is done by 'flagging' the address as an absolute address so that
arch_jump_destination() can calculate it as expected. Because code is
_always_ 4 bytes aligned, use bit 30 as flag.

Also add support for 'b' and 'ba' instructions. Objtool call them jumps.

And make sure the special 'bl .+4' used by clang in relocatable code is
not seen as an 'unannotated intra-function call'. clang should use the
special 'bcl 20,31,.+4' form like gcc but for the time being it does not
so lets work around that.

Link: https://github.com/llvm/llvm-project/issues/128644
Reviewed-by: Segher Boessenkool <segher@kewrnel.crashing.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/bf0b4d554547bc34fa3d1af5b4e62a84c0bc182b.1740470510.git.christophe.leroy@csgroup.eu

authored by

Christophe Leroy and committed by
Madhavan Srinivasan bb7f054f d856bc3a

+9 -1
+9 -1
tools/objtool/arch/powerpc/decode.c
··· 55 55 56 56 switch (opcode) { 57 57 case 18: /* b[l][a] */ 58 - if ((ins & 3) == 1) /* bl */ 58 + if (ins == 0x48000005) /* bl .+4 */ 59 + typ = INSN_OTHER; 60 + else if (ins & 1) /* bl[a] */ 59 61 typ = INSN_CALL; 62 + else /* b[a] */ 63 + typ = INSN_JUMP_UNCONDITIONAL; 60 64 61 65 imm = ins & 0x3fffffc; 62 66 if (imm & 0x2000000) 63 67 imm -= 0x4000000; 68 + imm |= ins & 2; /* AA flag */ 64 69 break; 65 70 } 66 71 ··· 82 77 83 78 unsigned long arch_jump_destination(struct instruction *insn) 84 79 { 80 + if (insn->immediate & 2) 81 + return insn->immediate & ~2; 82 + 85 83 return insn->offset + insn->immediate; 86 84 } 87 85