From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philipp Rudo Date: Thu, 20 Jan 2022 19:09:06 +0100 Subject: [PATCHv4 3/4] arm64: read VA_BITS from kcore for 52-bits VA kernel In-Reply-To: <20220118074812.27702-4-piliu@redhat.com> References: <20220118074812.27702-1-piliu@redhat.com> <20220118074812.27702-4-piliu@redhat.com> Message-ID: <20220120190906.2ec85ec9@rhtmp> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kexec@lists.infradead.org Hi Pingfan, On Tue, 18 Jan 2022 15:48:11 +0800 Pingfan Liu 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 > Cc: Kairui Song > Cc: Simon Horman > Cc: Philipp Rudo > To: kexec at lists.infradead.org looks good Reviewed-by: Philipp Rudo > --- > kexec/arch/arm64/kexec-arm64.c | 34 ++++++++++++++++++++++++++++++---- > util_lib/elf_info.c | 5 +++++ > util_lib/include/elf_info.h | 1 + > 3 files changed, 36 insertions(+), 4 deletions(-) > > diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c > index 33cc258..793799b 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 +876,18 @@ static inline void set_phys_offset(int64_t 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; > + > + > + /* For kernel older than v4.19 */ > + fprintf(stderr, "Warning, can't get the VA_BITS from kcore\n"); > + stext_sym_addr = get_kernel_sym("_stext"); > > if (stext_sym_addr == 0) { > fprintf(stderr, "Can't get the symbol of _stext.\n"); > @@ -900,6 +911,7 @@ static int get_va_bits(void) > return -1; > } > > +out: > dbgprintf("va_bits : %d\n", va_bits); > > return 0; > @@ -917,14 +929,27 @@ int get_page_offset(unsigned long *page_offset) > if (ret < 0) > return ret; > > - *page_offset = UINT64_MAX << (va_bits - 1); > + if (va_bits < 52) > + *page_offset = UINT64_MAX << (va_bits - 1); > + else > + *page_offset = UINT64_MAX << va_bits; > + > 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 +962,7 @@ 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/util_lib/elf_info.c b/util_lib/elf_info.c > index 5574c7f..d252eff 100644 > --- a/util_lib/elf_info.c > +++ b/util_lib/elf_info.c > @@ -310,6 +310,8 @@ int get_pt_load(int idx, > > #define NOT_FOUND_LONG_VALUE (-1) > > +void (*arch_scan_vmcoreinfo)(char *pos); > + > void scan_vmcoreinfo(char *start, size_t size) > { > char *last = start + size - 1; > @@ -551,6 +553,9 @@ void scan_vmcoreinfo(char *start, size_t size) > } > } > > + if (arch_scan_vmcoreinfo != NULL) > + (*arch_scan_vmcoreinfo)(pos); > + > if (last_line) > break; > } > diff --git a/util_lib/include/elf_info.h b/util_lib/include/elf_info.h > index f550d86..fdf4c3d 100644 > --- a/util_lib/include/elf_info.h > +++ b/util_lib/include/elf_info.h > @@ -31,5 +31,6 @@ int get_pt_load(int idx, > int read_phys_offset_elf_kcore(int fd, long *phys_off); > int read_elf(int fd); > void dump_dmesg(int fd, void (*handler)(char*, unsigned int)); > +extern void (*arch_scan_vmcoreinfo)(char *pos); > > #endif /* ELF_INFO_H */