[PATCHv2 0/3] arm64: make phys_to_virt() correct

[PATCHv2 0/3] arm64: make phys_to_virt() correct

[Pingfan Liu]

Currently phys_to_virt() does not work well on 52-bits VA arm64 kernel.
One issue is contributed by phys_offset not signed.
The other is contributed by wrong page_offset.

v1 -> v2
Fix broken patch [2/3] in v1
Move arch_scan_vmcoreinfo declaration to util_lib/include/elf_info.h
Using UINT64_MAX instread of 0xffffffffffffffff



Pingfan Liu (3):
  arm64: make phys_offset signed
  arm64/crashdump: unify routine to get page_offset
  arm64: read VA_BITS from kcore for 52-bits VA kernel

 kexec/arch/arm64/crashdump-arm64.c | 23 +-------------
 kexec/arch/arm64/kexec-arm64.c     | 48 +++++++++++++++++++++++-------
 kexec/arch/arm64/kexec-arm64.h     |  3 +-
 util_lib/elf_info.c                |  7 ++++-
 util_lib/include/elf_info.h        |  3 +-
 5 files changed, 48 insertions(+), 36 deletions(-)

-- 
2.31.1


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[PATCHv2 1/3] arm64: make phys_offset signed

[Pingfan Liu]

After kernel commit 7bc1a0f9e176 ("arm64: mm: use single quantity to
represent the PA to VA translation"), phys_offset can be negative if
running 52-bits kernel on 48-bits hardware.

So changing phys_offset from unsigned to signed.

Signed-off-by: Pingfan Liu <piliu@redhat.com>
---
 kexec/arch/arm64/kexec-arm64.c | 8 ++++----
 kexec/arch/arm64/kexec-arm64.h | 2 +-
 util_lib/elf_info.c            | 2 +-
 util_lib/include/elf_info.h    | 2 +-
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
index 6f572ed..7373fa3 100644
--- a/kexec/arch/arm64/kexec-arm64.c
+++ b/kexec/arch/arm64/kexec-arm64.c
@@ -859,7 +859,7 @@ void add_segment(struct kexec_info *info, const void *buf, size_t bufsz,
 	add_segment_phys_virt(info, buf, bufsz, base, memsz, 1);
 }
 
-static inline void set_phys_offset(uint64_t v, char *set_method)
+static inline void set_phys_offset(long v, char *set_method)
 {
 	if (arm64_mem.phys_offset == arm64_mem_ngv
 		|| v < arm64_mem.phys_offset) {
@@ -928,7 +928,7 @@ static int get_page_offset(void)
  * from VMCOREINFO note inside 'kcore'.
  */
 
-static int get_phys_offset_from_vmcoreinfo_pt_note(unsigned long *phys_offset)
+static int get_phys_offset_from_vmcoreinfo_pt_note(long *phys_offset)
 {
 	int fd, ret = 0;
 
@@ -948,7 +948,7 @@ static int get_phys_offset_from_vmcoreinfo_pt_note(unsigned long *phys_offset)
  * from PT_LOADs inside 'kcore'.
  */
 
-int get_phys_base_from_pt_load(unsigned long *phys_offset)
+int get_phys_base_from_pt_load(long *phys_offset)
 {
 	int i, fd, ret;
 	unsigned long long phys_start;
@@ -997,7 +997,7 @@ static bool to_be_excluded(char *str)
 int get_memory_ranges(struct memory_range **range, int *ranges,
 	unsigned long kexec_flags)
 {
-	unsigned long phys_offset = UINT64_MAX;
+	long phys_offset = (long)UINT64_MAX;
 	FILE *fp;
 	const char *iomem = proc_iomem();
 	char line[MAX_LINE], *str;
diff --git a/kexec/arch/arm64/kexec-arm64.h b/kexec/arch/arm64/kexec-arm64.h
index ed447ac..1844b67 100644
--- a/kexec/arch/arm64/kexec-arm64.h
+++ b/kexec/arch/arm64/kexec-arm64.h
@@ -58,7 +58,7 @@ extern off_t initrd_size;
  */
 
 struct arm64_mem {
-	uint64_t phys_offset;
+	long phys_offset;
 	uint64_t text_offset;
 	uint64_t image_size;
 	uint64_t vp_offset;
diff --git a/util_lib/elf_info.c b/util_lib/elf_info.c
index 51d8b92..5574c7f 100644
--- a/util_lib/elf_info.c
+++ b/util_lib/elf_info.c
@@ -1236,7 +1236,7 @@ int read_elf(int fd)
 	return 0;
 }
 
-int read_phys_offset_elf_kcore(int fd, unsigned long *phys_off)
+int read_phys_offset_elf_kcore(int fd, long *phys_off)
 {
 	int ret;
 
diff --git a/util_lib/include/elf_info.h b/util_lib/include/elf_info.h
index 4bc9279..f550d86 100644
--- a/util_lib/include/elf_info.h
+++ b/util_lib/include/elf_info.h
@@ -28,7 +28,7 @@ int get_pt_load(int idx,
 	unsigned long long *phys_end,
 	unsigned long long *virt_start,
 	unsigned long long *virt_end);
-int read_phys_offset_elf_kcore(int fd, unsigned long *phys_off);
+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));
 
-- 
2.31.1


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[PATCHv2 2/3] arm64/crashdump: unify routine to get page_offset

[Pingfan Liu]

There are two funcs to get page_offset:
  get_kernel_page_offset()
  get_page_offset()

Since get_kernel_page_offset() does not observe the kernel formula, and
remove it. Unify them in order to introduce 52-bits VA kernel more
easily in the coming patch.

Signed-off-by: Pingfan Liu <piliu@redhat.com>
---
 kexec/arch/arm64/crashdump-arm64.c | 23 +----------------------
 kexec/arch/arm64/kexec-arm64.c     |  8 ++++----
 kexec/arch/arm64/kexec-arm64.h     |  1 +
 3 files changed, 6 insertions(+), 26 deletions(-)

diff --git a/kexec/arch/arm64/crashdump-arm64.c b/kexec/arch/arm64/crashdump-arm64.c
index a02019a..0a8d44c 100644
--- a/kexec/arch/arm64/crashdump-arm64.c
+++ b/kexec/arch/arm64/crashdump-arm64.c
@@ -46,27 +46,6 @@ static struct crash_elf_info elf_info = {
 	.machine	= EM_AARCH64,
 };
 
-/*
- * Note: The returned value is correct only if !CONFIG_RANDOMIZE_BASE.
- */
-static uint64_t get_kernel_page_offset(void)
-{
-	int i;
-
-	if (elf_info.kern_vaddr_start == UINT64_MAX)
-		return UINT64_MAX;
-
-	/* Current max virtual memory range is 48-bits. */
-	for (i = 48; i > 0; i--)
-		if (!(elf_info.kern_vaddr_start & (1UL << i)))
-			break;
-
-	if (i <= 0)
-		return UINT64_MAX;
-	else
-		return UINT64_MAX << i;
-}
-
 /*
  * iomem_range_callback() - callback called for each iomem region
  * @data: not used
@@ -198,7 +177,7 @@ int load_crashdump_segments(struct kexec_info *info)
 	if (err)
 		return EFAILED;
 
-	elf_info.page_offset = get_kernel_page_offset();
+	get_page_offset(&elf_info.page_offset);
 	dbgprintf("%s: page_offset:   %016llx\n", __func__,
 			elf_info.page_offset);
 
diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
index 7373fa3..037e51c 100644
--- a/kexec/arch/arm64/kexec-arm64.c
+++ b/kexec/arch/arm64/kexec-arm64.c
@@ -909,7 +909,7 @@ static int get_va_bits(void)
  * get_page_offset - Helper for getting PAGE_OFFSET
  */
 
-static int get_page_offset(void)
+int get_page_offset(unsigned long *page_offset)
 {
 	int ret;
 
@@ -917,8 +917,8 @@ static int get_page_offset(void)
 	if (ret < 0)
 		return ret;
 
-	page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
-	dbgprintf("page_offset : %lx\n", page_offset);
+	*page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
+	dbgprintf("page_offset : %lx\n", *page_offset);
 
 	return 0;
 }
@@ -954,7 +954,7 @@ int get_phys_base_from_pt_load(long *phys_offset)
 	unsigned long long phys_start;
 	unsigned long long virt_start;
 
-	ret = get_page_offset();
+	ret = get_page_offset(&page_offset);
 	if (ret < 0)
 		return ret;
 
diff --git a/kexec/arch/arm64/kexec-arm64.h b/kexec/arch/arm64/kexec-arm64.h
index 1844b67..ed99d9d 100644
--- a/kexec/arch/arm64/kexec-arm64.h
+++ b/kexec/arch/arm64/kexec-arm64.h
@@ -69,6 +69,7 @@ extern struct arm64_mem arm64_mem;
 
 uint64_t get_phys_offset(void);
 uint64_t get_vp_offset(void);
+int get_page_offset(unsigned long *offset);
 
 static inline void reset_vp_offset(void)
 {
-- 
2.31.1


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[PATCHv2 3/3] arm64: read VA_BITS from kcore for 52-bits VA kernel

[Pingfan Liu]

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@redhat.com>
---
 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 037e51c..86aadf0 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(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;
+
+
+	/* 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 = (0xffffffffffffffffUL) << (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 */
-- 
2.31.1


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