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

From: Michael Ellerman
Date: Sun Jul 07 2019 - 20:56:57 EST


Christophe Leroy <christophe.leroy@xxxxxx> writes:
> To increase readability/maintainability, replace hard coded
> instructions values by symbolic names.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> ---
> 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,
...
> /*
> * 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` :)

Fixed now.

cheers