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

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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
This commit is contained in:
Christophe Leroy 2025-02-25 09:05:49 +01:00 • committed by Madhavan Srinivasan
parent d856bc3ac7
commit bb7f054f4d
1 changed files with 9 additions and 1 deletions
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10
tools/objtool/arch/powerpc/decode.c
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@ -55,12 +55,17 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
switch (opcode) {
case 18: /* b[l][a] */
if ((ins & 3) == 1) /* bl */
if (ins == 0x48000005) /* bl .+4 */
typ = INSN_OTHER;
else if (ins & 1) /* bl[a] */
typ = INSN_CALL;
else /* b[a] */
typ = INSN_JUMP_UNCONDITIONAL;
imm = ins & 0x3fffffc;
if (imm & 0x2000000)
imm -= 0x4000000;
imm |= ins & 2; /* AA flag */
break;
}
@ -77,6 +82,9 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
unsigned long arch_jump_destination(struct instruction *insn)
{
if (insn->immediate & 2)
return insn->immediate & ~2;
return insn->offset + insn->immediate;
}