Re: [PATCH 1/2] riscv, crash: don't export some symbols when CONFIG_MMU=n

Baoquan He
2023-12-05T07:18:26Z

On 12/04/23 at 11:14am, Randy Dunlap wrote:
......
> > ---
> > arch/riscv/kernel/crash_core.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/riscv/kernel/crash_core.c b/arch/riscv/kernel/crash_core.c
> > index 55f1d7856b54..8706736fd4e2 100644
> > --- a/arch/riscv/kernel/crash_core.c
> > +++ b/arch/riscv/kernel/crash_core.c
> > @@ -5,17 +5,19 @@
> >
> > void arch_crash_save_vmcoreinfo(void)
> > {
> > - VMCOREINFO_NUMBER(VA_BITS);
> > VMCOREINFO_NUMBER(phys_ram_base);
> >
> > vmcoreinfo_append_str("NUMBER(PAGE_OFFSET)=0x%lx\n", PAGE_OFFSET);
> > vmcoreinfo_append_str("NUMBER(VMALLOC_START)=0x%lx\n", VMALLOC_START);
> > vmcoreinfo_append_str("NUMBER(VMALLOC_END)=0x%lx\n", VMALLOC_END);
> > +#ifdef CONFIG_MMU
> > + VMCOREINFO_NUMBER(VA_BITS);
> > vmcoreinfo_append_str("NUMBER(VMEMMAP_START)=0x%lx\n", VMEMMAP_START);
> > vmcoreinfo_append_str("NUMBER(VMEMMAP_END)=0x%lx\n", VMEMMAP_END);
> > #ifdef CONFIG_64BIT
> > vmcoreinfo_append_str("NUMBER(MODULES_VADDR)=0x%lx\n", MODULES_VADDR);
> > vmcoreinfo_append_str("NUMBER(MODULES_END)=0x%lx\n", MODULES_END);
> > +#endif
> > #endif
> > vmcoreinfo_append_str("NUMBER(KERNEL_LINK_ADDR)=0x%lx\n", KERNEL_LINK_ADDR);
> > vmcoreinfo_append_str("NUMBER(va_kernel_pa_offset)=0x%lx\n",
>
> Both riscv 32-bit and 64-bit complain:
>
> ../arch/riscv/kernel/crash_core.c: In function 'arch_crash_save_vmcoreinfo':
> ../arch/riscv/kernel/crash_core.c:11:58: warning: format '%lx' expects argument of type 'long unsigned int', but argument 2 has type 'int' [-Wformat=]
> 11 | vmcoreinfo_append_str("NUMBER(VMALLOC_START)=0x%lx\n", VMALLOC_START);
> | ~~^
> | |
> | long unsigned int
> | %x

Thanks for all these testing.

This warning is irrelevant to the kexec patch, it's becasue
VMALLOC_START is defined as 0 which is int when CONFIG_MMU=n.

Below patch can fix the warning.

From 46984a0287e5f1b41ae3e9adfcfa0d26b71db8f4 Mon Sep 17 00:00:00 2001
From: Baoquan He <bhe@redhat.com>
Date: Tue, 5 Dec 2023 11:02:55 +0800
Subject: [PATCH] riscv: fix VMALLC_START definition
Content-type: text/plain

When below config items are set, compiler complained:

--------------------
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
......
-----------------------

-------------------------------------------------------------------
arch/riscv/kernel/crash_core.c: In function 'arch_crash_save_vmcoreinfo':
arch/riscv/kernel/crash_core.c:11:58: warning: format '%lx' expects argument of type 'long unsigned int', but argument 2 has type 'int' [-Wformat=]
11 | vmcoreinfo_append_str("NUMBER(VMALLOC_START)=0x%lx\n", VMALLOC_START);
| ~~^
| |
| long unsigned int
| %x
----------------------------------------------------------------------

This is because on riscv macro VMALLOC_START has different type when
CONFIG_MMU is set or unset.

arch/riscv/include/asm/pgtable.h:
--------------------------------------------------

Changing it to _AC(0, UL) in case CONFIG_MMU=n can fix the warning.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
arch/riscv/include/asm/pgtable.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 294044429e8e..ab00235b018f 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -899,7 +899,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
#define PAGE_KERNEL __pgprot(0)
#define swapper_pg_dir NULL
#define TASK_SIZE 0xffffffffUL
-#define VMALLOC_START 0
+#define VMALLOC_START _AC(0, UL)
#define VMALLOC_END TASK_SIZE

#endif /* !CONFIG_MMU */
--
2.41.0