Re: [PATCH v2 2/3] riscv/purgatory: do not link with string.o and its dependencies

[Palmer Dabbelt]

On Wed, 26 Jul 2023 09:33:49 PDT (-0700), Conor Dooley wrote:
> On Wed, Jul 26, 2023 at 11:54:00AM +0200, Petr Tesarik wrote:
> > From: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx>
> >
> > Linking with this object file makes kexec_file_load(2) fail because of
> > multiple unknown relocation types:
> >
> > - R_RISCV_ADD16, R_RISCV_SUB16: used by alternatives in strcmp()
> > - R_RISCV_GOT_HI20: used to resolve _ctype in strcasecmp()
> >
> > All this hassle is needed for one single call to memcmp() from
> > verify_sha256_digest() to compare 32 bytes of SHA256 checksum.
> >
> > Simply replace this memcmp() call with an explicit loop over those 32 bytes
> > and remove the need to link with string.o and all the other object files
> > that provide undefined symbols from that object file.
> >
> > Fixes: 838b3e28488f ("RISC-V: Load purgatory in kexec_file")
> > Signed-off-by: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx>
>
> This version keeps the automation happy,
> Acked-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>

Oddly enough, this breaks my builds.  I tried fixing the first one with
something like

   From 41c5a952f77e53bf4201296abff0132725aa19e6 Mon Sep 17 00:00:00 2001
   From: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
   Date: Wed, 2 Aug 2023 20:22:33 -0700
   Subject: [PATCH] RISC-V: Include io from timex
   
   Without this I get some implicit declarations.
   
     CC      arch/riscv/kernel/asm-offsets.s
   In file included from linux/include/linux/timex.h:67,
                    from linux/include/linux/time32.h:13,
                    from linux/include/linux/time.h:60,
                    from linux/include/linux/ktime.h:24,
                    from linux/include/linux/timer.h:6,
                    from linux/include/linux/workqueue.h:9,
                    from linux/include/linux/mm_types.h:19,
                    from linux/include/linux/mmzone.h:22,
                    from linux/include/linux/gfp.h:7,
                    from linux/include/linux/mm.h:7,
                    from linux/arch/riscv/kernel/asm-offsets.c:10:
   linux/arch/riscv/include/asm/timex.h: In function 'get_cycles':
   linux/arch/riscv/include/asm/timex.h:25:16: error: implicit declaration of function 'readl_relaxed' [-Werror=implicit-function-declaration]
      25 |         return readl_relaxed(((u32 *)clint_time_val));
         |
   
   Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
   ---
    arch/riscv/include/asm/timex.h | 1 +
    1 file changed, 1 insertion(+)
   
   diff --git a/arch/riscv/include/asm/timex.h b/arch/riscv/include/asm/timex.h
   index a06697846e69..1a4d181193e0 100644
   --- a/arch/riscv/include/asm/timex.h
   +++ b/arch/riscv/include/asm/timex.h
   @@ -7,6 +7,7 @@
    #define _ASM_RISCV_TIMEX_H
    
    #include <asm/csr.h>
   +#include <asm/io.h>
    
    typedef unsigned long cycles_t;

   -- 
   2.41.0

The other two look fine and are somewhat independent, so I've picked those up
for fixes.

Thanks!

> Thanks,
> Conor.