Re: [PATCH v3 3/3] powerpc/module64: Use symbolic instructions names.

Le 08/07/2019 à 02:56, Michael Ellerman a écrit :

Christophe Leroy [off-list ref] writes:

quoted

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

Signed-off-by: Christophe Leroy <redacted>
---
v3: fixed warning by adding () in an 'if' around X | Y (unlike said in v2 history, this change was forgotten in v2)
v2: rearranged comments

  arch/powerpc/kernel/module_64.c | 53 +++++++++++++++++++++++++++--------------
  1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index c2e1b06253b8..b33a5d5e2d35 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c

@@ -704,18 +711,21 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,

...

quoted

  			/*
  			 * If found, replace it with:
  			 *	addis r2, r12, (.TOC.-func)@ha
  			 *	addi r2, r12, (.TOC.-func)@l
  			 */
-			((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value);
-			((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
+			((uint32_t *)location)[0] = PPC_INST_ADDIS | __PPC_RT(R2) |
+						    __PPC_RA(R12) | PPC_HA(value);
+			((uint32_t *)location)[1] = PPC_INST_ADDI | __PPC_RT(R2) |
+						    __PPC_RA(R12) | PPC_LO(value);
  			break;

This was crashing and it's amazing how long you can stare at a
disassembly and not see the difference between `r2` and `r12` :)

Argh, yes. I was misleaded by the comment I guess. Sorry for that and 
thanks for fixing.

Christophe

Fixed now.

cheers