Re: [PATCH] powerpc: Remove klimit

[Kefeng Wang]

On 2021/6/4 17:57, Christophe Leroy wrote:

klimit is a global variable initialised at build time with the
value of _end.

This variable is never modified, so _end symbol can be used directly.

Remove klimit.

Reviewed-by: Kefeng Wang <wangkefeng.w...@huawei.com>

Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
Cc: Kefeng Wang <wangkefeng.w...@huawei.com>
---
  arch/powerpc/include/asm/setup.h             | 1 -
  arch/powerpc/kernel/head_book3s_32.S         | 6 ++----
  arch/powerpc/kernel/prom.c                   | 2 +-
  arch/powerpc/kernel/setup-common.c           | 4 +---
  arch/powerpc/platforms/powermac/bootx_init.c | 2 +-
  5 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index e89bfebd4e00..6c1a7d217d1a 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -10,7 +10,6 @@ extern void ppc_printk_progress(char *s, unsigned short hex);
  extern unsigned int rtas_data;
  extern unsigned long long memory_limit;
  extern bool init_mem_is_free;
-extern unsigned long klimit;
  extern void *zalloc_maybe_bootmem(size_t size, gfp_t mask);

struct device_node;

diff --git a/arch/powerpc/kernel/head_book3s_32.S 
b/arch/powerpc/kernel/head_book3s_32.S
index 326262030279..b724e88bcdaf 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -766,9 +766,6 @@ PerformanceMonitor:
   * the kernel image to physical address PHYSICAL_START.
   */
  relocate_kernel:
-       addis   r9,r26,klimit@ha        /* fetch klimit */
-       lwz     r25,klimit@l(r9)
-       addis   r25,r25,-KERNELBASE@h
        lis     r3,PHYSICAL_START@h     /* Destination base address */
        li      r6,0                    /* Destination offset */
        li      r5,0x4000               /* # bytes of memory to copy */
@@ -776,7 +773,8 @@ relocate_kernel:
        addi    r0,r3,4f@l              /* jump to the address of 4f */
        mtctr   r0                      /* in copy and do the rest. */
        bctr                            /* jump to the copy */
-4:     mr      r5,r25
+4:     lis     r5,_end-KERNELBASE@h
+       ori     r5,r5,_end-KERNELBASE@l
        bl      copy_and_flush          /* copy the rest */
        b       turn_on_mmu

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c

index fbe9deebc8e1..f620e04dc9bf 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -758,7 +758,7 @@ void __init early_init_devtree(void *params)
                first_memblock_size = min_t(u64, first_memblock_size, 
memory_limit);
        setup_initial_memory_limit(memstart_addr, first_memblock_size);
        /* Reserve MEMBLOCK regions used by kernel, initrd, dt, etc... */
-       memblock_reserve(PHYSICAL_START, __pa(klimit) - PHYSICAL_START);
+       memblock_reserve(PHYSICAL_START, __pa(_end) - PHYSICAL_START);
        /* If relocatable, reserve first 32k for interrupt vectors etc. */
        if (PHYSICAL_START > MEMORY_START)
                memblock_reserve(MEMORY_START, 0x8000);
diff --git a/arch/powerpc/kernel/setup-common.c 
b/arch/powerpc/kernel/setup-common.c
index 74a98fff2c2f..138bb7f49ef9 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -91,8 +91,6 @@ EXPORT_SYMBOL_GPL(boot_cpuid);
  int dcache_bsize;
  int icache_bsize;

-unsigned long klimit = (unsigned long) _end;

-
  /*
   * This still seems to be needed... -- paulus
   */
@@ -930,7 +928,7 @@ void __init setup_arch(char **cmdline_p)
        init_mm.start_code = (unsigned long)_stext;
        init_mm.end_code = (unsigned long) _etext;
        init_mm.end_data = (unsigned long) _edata;
-       init_mm.brk = klimit;
+       init_mm.brk = (unsigned long)_end;

mm_iommu_init(&init_mm);

        irqstack_early_init();
diff --git a/arch/powerpc/platforms/powermac/bootx_init.c 
b/arch/powerpc/platforms/powermac/bootx_init.c
index 9d4ecd292255..d20ef35e6d9d 100644
--- a/arch/powerpc/platforms/powermac/bootx_init.c
+++ b/arch/powerpc/platforms/powermac/bootx_init.c
@@ -433,7 +433,7 @@ static void __init btext_welcome(boot_infos_t *bi)
        bootx_printf("\nframe buffer at  : 0x%x", bi->dispDeviceBase);
        bootx_printf(" (phys), 0x%x", bi->logicalDisplayBase);
        bootx_printf(" (log)");
-       bootx_printf("\nklimit           : 0x%x",(unsigned long)klimit);
+       bootx_printf("\nklimit           : 0x%x",(unsigned long)_end);
        bootx_printf("\nboot_info at     : 0x%x", bi);
        __asm__ __volatile__ ("mfmsr %0" : "=r" (flags));
        bootx_printf("\nMSR              : 0x%x", flags);