[PATCH v3 2/3] powerpc/module32: Use symbolic instructions names.

From: Christophe Leroy
Date: Fri May 03 2019 - 02:40:48 EST


To increase readability/maintainability, replace hard coded
instructions values by symbolic names.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
v3: no change
v2: Remove the ENTRY_JMP0 and ENTRY_JMP1 macros ; left real instructions as a comment.

arch/powerpc/kernel/module_32.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/module_32.c b/arch/powerpc/kernel/module_32.c
index 88d83771f462..9cf201111d6c 100644
--- a/arch/powerpc/kernel/module_32.c
+++ b/arch/powerpc/kernel/module_32.c
@@ -172,10 +172,12 @@ int module_frob_arch_sections(Elf32_Ehdr *hdr,

static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
{
- if (entry->jump[0] == 0x3d800000 + ((val + 0x8000) >> 16)
- && entry->jump[1] == 0x398c0000 + (val & 0xffff))
- return 1;
- return 0;
+ if (entry->jump[0] != (PPC_INST_ADDIS | __PPC_RT(R12) | PPC_HA(val)))
+ return 0;
+ if (entry->jump[1] != (PPC_INST_ADDI | __PPC_RT(R12) | __PPC_RA(R12) |
+ PPC_LO(val)))
+ return 0;
+ return 1;
}

/* Set up a trampoline in the PLT to bounce us to the distant function */
@@ -200,10 +202,16 @@ static uint32_t do_plt_call(void *location,
entry++;
}

- entry->jump[0] = 0x3d800000+((val+0x8000)>>16); /* lis r12,sym@ha */
- entry->jump[1] = 0x398c0000 + (val&0xffff); /* addi r12,r12,sym@l*/
- entry->jump[2] = 0x7d8903a6; /* mtctr r12 */
- entry->jump[3] = 0x4e800420; /* bctr */
+ /*
+ * lis r12, sym@ha
+ * addi r12, r12, sym@l
+ * mtctr r12
+ * bctr
+ */
+ entry->jump[0] = PPC_INST_ADDIS | __PPC_RT(R12) | PPC_HA(val);
+ entry->jump[1] = PPC_INST_ADDI | __PPC_RT(R12) | __PPC_RA(R12) | PPC_LO(val);
+ entry->jump[2] = PPC_INST_MTCTR | __PPC_RS(R12);
+ entry->jump[3] = PPC_INST_BCTR;

pr_debug("Initialized plt for 0x%x at %p\n", val, entry);
return (uint32_t)entry;
--
2.13.3