On Wed, Dec 15, 2021 at 9:35 PM Philipp Rudo <prudo@xxxxxxxxxx> wrote:
>
> Hi Pingfang,
>
> On Fri, 10 Dec 2021 11:07:35 +0800
> Pingfan Liu <piliu@xxxxxxxxxx> wrote:
>
> > phys_to_virt() calculates virtual address. As a important factor,
> > page_offset is excepted to be accurate.
> >
> > Since arm64 kernel exposes va_bits through vmcore, using it.
> >
> > Signed-off-by: Pingfan Liu <piliu@xxxxxxxxxx>
> > ---
> > kexec/arch/arm64/kexec-arm64.c | 31 +++++++++++++++++++++++++++----
> > kexec/arch/arm64/kexec-arm64.h | 1 +
> > util_lib/elf_info.c | 5 +++++
> > 3 files changed, 33 insertions(+), 4 deletions(-)
> >
> > diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
> > index bd650e6..ccc92db 100644
> > --- a/kexec/arch/arm64/kexec-arm64.c
> > +++ b/kexec/arch/arm64/kexec-arm64.c
> > @@ -54,7 +54,7 @@
> > static bool try_read_phys_offset_from_kcore = false;
> >
> > /* Machine specific details. */
> > -static int va_bits;
> > +static int va_bits = -1;
> > static unsigned long page_offset;
> >
> > /* Global varables the core kexec routines expect. */
> > @@ -876,7 +876,15 @@ static inline void set_phys_offset(long v, char *set_method)
> >
> > static int get_va_bits(void)
> > {
> > - unsigned long long stext_sym_addr = get_kernel_sym("_stext");
> > + unsigned long long stext_sym_addr;
> > +
> > + /*
> > + * if already got from kcore
> > + */
> > + if (va_bits != -1)
> > + goto out;
> > +
> > + stext_sym_addr = get_kernel_sym("_stext");
> >
> > if (stext_sym_addr == 0) {
> > fprintf(stderr, "Can't get the symbol of _stext.\n");
> > @@ -900,6 +908,7 @@ static int get_va_bits(void)
> > return -1;
> > }
> >
> > +out:
> > dbgprintf("va_bits : %d\n", va_bits);
> >
> > return 0;
> > @@ -917,14 +926,27 @@ int get_page_offset(unsigned long *page_offset)
> > if (ret < 0)
> > return ret;
> >
> > - page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
> > + if (va_bits < 52)
> > + *page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
> > + else
> > + *page_offset = (0xffffffffffffffffUL) << va_bits;
>
> wouldn't it make sense to use ULONG_MAX here? At least for me it would
> be much better readable.
>
Yes, I tend to agree and will update it in V2 (if there is no need to
compile it on 32-bits machine, which I consider as a rare case
nowadays.)
> > dbgprintf("page_offset : %lx\n", page_offset);
> >
> > return 0;
> > }
> >
> > +static void arm64_scan_vmcoreinfo(char *pos)
> > +{
> > + const char *str;
> > +
> > + str = "NUMBER(VA_BITS)=";
> > + if (memcmp(str, pos, strlen(str)) == 0)
> > + va_bits = strtoul(pos + strlen(str), NULL, 10);
> > +}
> > +
> > /**
> > - * get_phys_offset_from_vmcoreinfo_pt_note - Helper for getting PHYS_OFFSET
> > + * get_phys_offset_from_vmcoreinfo_pt_note - Helper for getting PHYS_OFFSET (and va_bits)
> > * from VMCOREINFO note inside 'kcore'.
> > */
> >
> > @@ -937,6 +959,7 @@ static int get_phys_offset_from_vmcoreinfo_pt_note(long *phys_offset)
> > return EFAILED;
> > }
> >
> > + arch_scan_vmcoreinfo = arm64_scan_vmcoreinfo;
> > ret = read_phys_offset_elf_kcore(fd, phys_offset);
> >
> > close(fd);
> > diff --git a/kexec/arch/arm64/kexec-arm64.h b/kexec/arch/arm64/kexec-arm64.h
> > index ed99d9d..d291705 100644
> > --- a/kexec/arch/arm64/kexec-arm64.h
> > +++ b/kexec/arch/arm64/kexec-arm64.h
> > @@ -66,6 +66,7 @@ struct arm64_mem {
> >
> > #define arm64_mem_ngv UINT64_MAX
> > extern struct arm64_mem arm64_mem;
> > +extern void (*arch_scan_vmcoreinfo)(char *pos);
>
> This definition isn't arm64 specific. I think this should go to
> util_lib/include/elf_info.h.
>
Good suggestion and update it in V2.
Thanks,
Pingfan
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