[PATCH 0/4 v2] Limit the size of vmcore-dmesg.txt to 2G

[PATCH 0/4 v2] Limit the size of vmcore-dmesg.txt to 2G

[Lianbo Jiang]

[PATCH 1/4] Cleanup: remove the read_elf_kcore()
Here, no need to wrap the read_elf() again, lets invoke it directly.
So remove the read_elf_kcore() and clean up redundant code.

[PATCH 2/4] Fix an error definition about the variable 'fname'
The variable 'fname' is mistakenly defined two twice, the first definition
is in the vmcore-dmesg.c, and the second definition is in the elf_info.c.
That is confused and incorrect although it's a static type, because the
value of variable 'fname' is not assigned(set) in elf_info.c. Anyway, its
value will be always 'null' when printing an error information.

[PATCH 3/4] Cleanup: move it back from util_lib/elf_info.c
Some code related to vmcore-dmesg.c is put into the util_lib, which
is not very reasonable, so lets move it back and tidy up those code.
In addition, that will also help to limit the size of vmcore-dmesg.txt.

[PATCH 4/4] Limit the size of vmcore-dmesg.txt to 2G
With some corrupted vmcore files, the vmcore-dmesg.txt file may
grow forever till the kdump disk becomes full. Lets limit the
size of vmcore-dmesg.txt to avoid such problems.

BTW: I tested this patch series on x86 64 and arm64, it also worked well.

Changes since v1:
[1] split them([patch 1/4] and [patch 2/4]) into a separate patch.
[2] remove a typedef definition for handler.
[3] remove some changes of variable 'fname' and fix its error.

Lianbo Jiang (4):
  Cleanup: remove the read_elf_kcore()
  Fix an error definition about the variable 'fname'
  Cleanup: move it back from util_lib/elf_info.c
  Limit the size of vmcore-dmesg.txt to 2G

 kexec/arch/arm64/kexec-arm64.c |  2 +-
 util_lib/elf_info.c            | 65 ++++++++--------------------------
 util_lib/include/elf_info.h    |  4 +--
 vmcore-dmesg/vmcore-dmesg.c    | 42 ++++++++++++++++++++--
 4 files changed, 57 insertions(+), 56 deletions(-)

-- 
2.17.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH 1/4 v2] Cleanup: remove the read_elf_kcore()

[Lianbo Jiang]

Here, no need to wrap the read_elf() again, lets invoke it directly.
So remove the read_elf_kcore() and clean up redundant code.

Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
---
 kexec/arch/arm64/kexec-arm64.c |  2 +-
 util_lib/elf_info.c            | 15 ++-------------
 util_lib/include/elf_info.h    |  2 +-
 3 files changed, 4 insertions(+), 15 deletions(-)

diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
index eb3a3a37307c..6ad3b0a134b3 100644
--- a/kexec/arch/arm64/kexec-arm64.c
+++ b/kexec/arch/arm64/kexec-arm64.c
@@ -889,7 +889,7 @@ int get_phys_base_from_pt_load(unsigned long *phys_offset)
 		return EFAILED;
 	}
 
-	read_elf_kcore(fd);
+	read_elf(fd);
 
 	for (i = 0; get_pt_load(i,
 		    &phys_start, NULL, &virt_start, NULL);
diff --git a/util_lib/elf_info.c b/util_lib/elf_info.c
index 90a3b21662e7..d9397ecd8626 100644
--- a/util_lib/elf_info.c
+++ b/util_lib/elf_info.c
@@ -764,7 +764,7 @@ static void dump_dmesg(int fd)
 		dump_dmesg_legacy(fd);
 }
 
-static int read_elf(int fd)
+int read_elf(int fd)
 {
 	int ret;
 
@@ -824,24 +824,13 @@ int read_elf_vmcore(int fd)
 	return 0;
 }
 
-int read_elf_kcore(int fd)
-{
-	int ret;
-
-	ret = read_elf(fd);
-	if (ret != 0)
-		return ret;
-
-	return 0;
-}
-
 int read_phys_offset_elf_kcore(int fd, unsigned long *phys_off)
 {
 	int ret;
 
 	*phys_off = UINT64_MAX;
 
-	ret = read_elf_kcore(fd);
+	ret = read_elf(fd);
 	if (!ret) {
 		/* If we have a valid 'PHYS_OFFSET' by now,
 		 * return it to the caller now.
diff --git a/util_lib/include/elf_info.h b/util_lib/include/elf_info.h
index 1a4debd2d4ba..c328a1b0ecf2 100644
--- a/util_lib/include/elf_info.h
+++ b/util_lib/include/elf_info.h
@@ -29,7 +29,7 @@ int get_pt_load(int idx,
 	unsigned long long *virt_start,
 	unsigned long long *virt_end);
 int read_phys_offset_elf_kcore(int fd, unsigned long *phys_off);
-int read_elf_kcore(int fd);
+int read_elf(int fd);
 int read_elf_vmcore(int fd);
 
 #endif /* ELF_INFO_H */
-- 
2.17.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH 2/4 v2] Fix an error definition about the variable 'fname'

[Lianbo Jiang]

The variable 'fname' is mistakenly defined two twice, the first definition
is in the vmcore-dmesg.c, and the second definition is in the elf_info.c.
That is confused and incorrect although it's a static type, because the
value of variable 'fname' is not assigned(set) in elf_info.c. Anyway, its
value will be always 'null' when printing an error information.

Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
---
 util_lib/elf_info.c         | 2 +-
 vmcore-dmesg/vmcore-dmesg.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/util_lib/elf_info.c b/util_lib/elf_info.c
index d9397ecd8626..5d0efaafab53 100644
--- a/util_lib/elf_info.c
+++ b/util_lib/elf_info.c
@@ -20,7 +20,7 @@
 /* The 32bit and 64bit note headers make it clear we don't care */
 typedef Elf32_Nhdr Elf_Nhdr;
 
-static const char *fname;
+const char *fname;
 static Elf64_Ehdr ehdr;
 static Elf64_Phdr *phdr;
 static int num_pt_loads;
diff --git a/vmcore-dmesg/vmcore-dmesg.c b/vmcore-dmesg/vmcore-dmesg.c
index 7a386b380291..bebc348a657e 100644
--- a/vmcore-dmesg/vmcore-dmesg.c
+++ b/vmcore-dmesg/vmcore-dmesg.c
@@ -3,7 +3,7 @@
 /* The 32bit and 64bit note headers make it clear we don't care */
 typedef Elf32_Nhdr Elf_Nhdr;
 
-static const char *fname;
+extern const char *fname;
 
 int main(int argc, char **argv)
 {
-- 
2.17.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH 3/4 v2] Cleanup: move it back from util_lib/elf_info.c

[Lianbo Jiang]

Some code related to vmcore-dmesg.c is put into the util_lib, which
is not very reasonable, so lets move it back and tidy up those code.

In addition, that will also help to limit the size of vmcore-dmesg.txt
in vmcore-dmesg.c instead of elf_info.c.

Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
---
 util_lib/elf_info.c         | 48 +++++++++----------------------------
 util_lib/include/elf_info.h |  2 +-
 vmcore-dmesg/vmcore-dmesg.c | 30 ++++++++++++++++++++++-
 3 files changed, 41 insertions(+), 39 deletions(-)

diff --git a/util_lib/elf_info.c b/util_lib/elf_info.c
index 5d0efaafab53..2bce5cb1713c 100644
--- a/util_lib/elf_info.c
+++ b/util_lib/elf_info.c
@@ -531,19 +531,7 @@ static int32_t read_file_s32(int fd, uint64_t addr)
 	return read_file_u32(fd, addr);
 }
 
-static void write_to_stdout(char *buf, unsigned int nr)
-{
-	ssize_t ret;
-
-	ret = write(STDOUT_FILENO, buf, nr);
-	if (ret != nr) {
-		fprintf(stderr, "Failed to write out the dmesg log buffer!:"
-			" %s\n", strerror(errno));
-		exit(54);
-	}
-}
-
-static void dump_dmesg_legacy(int fd)
+static void dump_dmesg_legacy(int fd, void (*handler)(char*, unsigned int))
 {
 	uint64_t log_buf, log_buf_offset;
 	unsigned log_end, logged_chars, log_end_wrapped;
@@ -604,7 +592,8 @@ static void dump_dmesg_legacy(int fd)
 	 */
 	logged_chars = log_end < log_buf_len ? log_end : log_buf_len;
 
-	write_to_stdout(buf + (log_buf_len - logged_chars), logged_chars);
+	if (handler)
+		handler(buf + (log_buf_len - logged_chars), logged_chars);
 }
 
 static inline uint16_t struct_val_u16(char *ptr, unsigned int offset)
@@ -623,7 +612,7 @@ static inline uint64_t struct_val_u64(char *ptr, unsigned int offset)
 }
 
 /* Read headers of log records and dump accordingly */
-static void dump_dmesg_structured(int fd)
+static void dump_dmesg_structured(int fd, void (*handler)(char*, unsigned int))
 {
 #define OUT_BUF_SIZE	4096
 	uint64_t log_buf, log_buf_offset, ts_nsec;
@@ -733,7 +722,8 @@ static void dump_dmesg_structured(int fd)
 				out_buf[len++] = c;
 
 			if (len >= OUT_BUF_SIZE - 64) {
-				write_to_stdout(out_buf, len);
+				if (handler)
+					handler(out_buf, len);
 				len = 0;
 			}
 		}
@@ -752,16 +742,16 @@ static void dump_dmesg_structured(int fd)
 			current_idx += loglen;
 	}
 	free(buf);
-	if (len)
-		write_to_stdout(out_buf, len);
+	if (len && handler)
+		handler(out_buf, len);
 }
 
-static void dump_dmesg(int fd)
+void dump_dmesg(int fd, void (*handler)(char*, unsigned int))
 {
 	if (log_first_idx_vaddr)
-		dump_dmesg_structured(fd);
+		dump_dmesg_structured(fd, handler);
 	else
-		dump_dmesg_legacy(fd);
+		dump_dmesg_legacy(fd, handler);
 }
 
 int read_elf(int fd)
@@ -808,22 +798,6 @@ int read_elf(int fd)
 	return 0;
 }
 
-int read_elf_vmcore(int fd)
-{
-	int ret;
-
-	ret = read_elf(fd);
-	if (ret > 0) {
-		fprintf(stderr, "Unable to read ELF information"
-			" from vmcore\n");
-		return ret;
-	}
-
-	dump_dmesg(fd);
-
-	return 0;
-}
-
 int read_phys_offset_elf_kcore(int fd, unsigned long *phys_off)
 {
 	int ret;
diff --git a/util_lib/include/elf_info.h b/util_lib/include/elf_info.h
index c328a1b0ecf2..4bc9279ba603 100644
--- a/util_lib/include/elf_info.h
+++ b/util_lib/include/elf_info.h
@@ -30,6 +30,6 @@ int get_pt_load(int idx,
 	unsigned long long *virt_end);
 int read_phys_offset_elf_kcore(int fd, unsigned long *phys_off);
 int read_elf(int fd);
-int read_elf_vmcore(int fd);
+void dump_dmesg(int fd, void (*handler)(char*, unsigned int));
 
 #endif /* ELF_INFO_H */
diff --git a/vmcore-dmesg/vmcore-dmesg.c b/vmcore-dmesg/vmcore-dmesg.c
index bebc348a657e..fe7df8ec372c 100644
--- a/vmcore-dmesg/vmcore-dmesg.c
+++ b/vmcore-dmesg/vmcore-dmesg.c
@@ -5,6 +5,34 @@ typedef Elf32_Nhdr Elf_Nhdr;
 
 extern const char *fname;
 
+static void write_to_stdout(char *buf, unsigned int nr)
+{
+	ssize_t ret;
+
+	ret = write(STDOUT_FILENO, buf, nr);
+	if (ret != nr) {
+		fprintf(stderr, "Failed to write out the dmesg log buffer!:"
+			" %s\n", strerror(errno));
+		exit(54);
+	}
+}
+
+static int read_vmcore_dmesg(int fd, void (*handler)(char*, unsigned int))
+{
+	int ret;
+
+	ret = read_elf(fd);
+	if (ret > 0) {
+		fprintf(stderr, "Unable to read ELF information"
+			" from vmcore\n");
+		return ret;
+	}
+
+	dump_dmesg(fd, handler);
+
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
 	ssize_t ret;
@@ -23,7 +51,7 @@ int main(int argc, char **argv)
 		return 2;
 	}
 
-	ret = read_elf_vmcore(fd);
+	ret = read_vmcore_dmesg(fd, write_to_stdout);
 	
 	close(fd);
 
-- 
2.17.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH 4/4 v2] Limit the size of vmcore-dmesg.txt to 2G

[Lianbo Jiang]

With some corrupted vmcore files, the vmcore-dmesg.txt file may grow
forever till the kdump disk becomes full, and also probably causes
the disk error messages as follow:
...
sd 0:0:0:0: [sda] tag#6 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
sd 0:0:0:0: [sda] tag#6 CDB: Read(10) 28 00 08 06 4c 98 00 00 08 00
blk_update_request: I/O error, dev sda, sector 134630552
sd 0:0:0:0: [sda] tag#7 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
sd 0:0:0:0: [sda] tag#7 CDB: Read(10) 28 00 08 06 4c 98 00 00 08 00
blk_update_request: I/O error, dev sda, sector 134630552
...

If vmcore-dmesg.txt occupies the whole disk, the vmcore can not be
saved, this is also a problem.

Lets limit the size of vmcore-dmesg.txt to avoid such problems.

Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
---
 vmcore-dmesg/vmcore-dmesg.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/vmcore-dmesg/vmcore-dmesg.c b/vmcore-dmesg/vmcore-dmesg.c
index fe7df8ec372c..81c2a58c9d86 100644
--- a/vmcore-dmesg/vmcore-dmesg.c
+++ b/vmcore-dmesg/vmcore-dmesg.c
@@ -5,9 +5,19 @@ typedef Elf32_Nhdr Elf_Nhdr;
 
 extern const char *fname;
 
+/* stole this macro from kernel printk.c */
+#define LOG_BUF_LEN_MAX (uint32_t)(1 << 31)
+
 static void write_to_stdout(char *buf, unsigned int nr)
 {
 	ssize_t ret;
+	static uint32_t n_bytes = 0;
+
+	n_bytes += nr;
+	if (n_bytes > LOG_BUF_LEN_MAX) {
+		fprintf(stderr, "The vmcore-dmesg.txt over 2G in size is not supported.\n");
+		exit(53);
+	}
 
 	ret = write(STDOUT_FILENO, buf, nr);
 	if (ret != nr) {
-- 
2.17.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

Re: [PATCH 0/4 v2] Limit the size of vmcore-dmesg.txt to 2G

[lijiang]

Hi, Simon and other reviewers, any comment about v2?

Thanks.
Lianbo


> [PATCH 1/4] Cleanup: remove the read_elf_kcore()
> Here, no need to wrap the read_elf() again, lets invoke it directly.
> So remove the read_elf_kcore() and clean up redundant code.
> 
> [PATCH 2/4] Fix an error definition about the variable 'fname'
> The variable 'fname' is mistakenly defined two twice, the first definition
> is in the vmcore-dmesg.c, and the second definition is in the elf_info.c.
> That is confused and incorrect although it's a static type, because the
> value of variable 'fname' is not assigned(set) in elf_info.c. Anyway, its
> value will be always 'null' when printing an error information.
> 
> [PATCH 3/4] Cleanup: move it back from util_lib/elf_info.c
> Some code related to vmcore-dmesg.c is put into the util_lib, which
> is not very reasonable, so lets move it back and tidy up those code.
> In addition, that will also help to limit the size of vmcore-dmesg.txt.
> 
> [PATCH 4/4] Limit the size of vmcore-dmesg.txt to 2G
> With some corrupted vmcore files, the vmcore-dmesg.txt file may
> grow forever till the kdump disk becomes full. Lets limit the
> size of vmcore-dmesg.txt to avoid such problems.
> 
> BTW: I tested this patch series on x86 64 and arm64, it also worked well.
> 
> Changes since v1:
> [1] split them([patch 1/4] and [patch 2/4]) into a separate patch.
> [2] remove a typedef definition for handler.
> [3] remove some changes of variable 'fname' and fix its error.
> 
> Lianbo Jiang (4):
>   Cleanup: remove the read_elf_kcore()
>   Fix an error definition about the variable 'fname'
>   Cleanup: move it back from util_lib/elf_info.c
>   Limit the size of vmcore-dmesg.txt to 2G
> 
>  kexec/arch/arm64/kexec-arm64.c |  2 +-
>  util_lib/elf_info.c            | 65 ++++++++--------------------------
>  util_lib/include/elf_info.h    |  4 +--
>  vmcore-dmesg/vmcore-dmesg.c    | 42 ++++++++++++++++++++--
>  4 files changed, 57 insertions(+), 56 deletions(-)
> 

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

Re: [PATCH 0/4 v2] Limit the size of vmcore-dmesg.txt to 2G

[Simon Horman]

On Wed, Aug 28, 2019 at 05:18:58PM +0800, lijiang wrote:
> Hi, Simon and other reviewers, any comment about v2?

Hi,

sorry for the extended delay.
I will look over this.

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

Re: [PATCH 0/4 v2] Limit the size of vmcore-dmesg.txt to 2G

[lijiang]

在 2019年09月03日 22:37, Simon Horman 写道:
> On Wed, Aug 28, 2019 at 05:18:58PM +0800, lijiang wrote:
>> Hi, Simon and other reviewers, any comment about v2?
> 
> Hi,
> 
> sorry for the extended delay.
> I will look over this.
> 
Never mind. Any suggestions will be appreciated.

Thank you in advance.

Lianbo

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

Re: [PATCH 0/4 v2] Limit the size of vmcore-dmesg.txt to 2G

[Simon Horman]

On Wed, Sep 04, 2019 at 09:29:20PM +0800, lijiang wrote:
> 在 2019年09月03日 22:37, Simon Horman 写道:
> > On Wed, Aug 28, 2019 at 05:18:58PM +0800, lijiang wrote:
> >> Hi, Simon and other reviewers, any comment about v2?
> > 
> > Hi,
> > 
> > sorry for the extended delay.
> > I will look over this.
> > 
> Never mind. Any suggestions will be appreciated.
> 
> Thank you in advance.

Sorry once again for the delay.

I have applied this series.

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

Re: [PATCH 0/4 v2] Limit the size of vmcore-dmesg.txt to 2G

[lijiang]

在 2019年09月08日 20:40, Simon Horman 写道:
> On Wed, Sep 04, 2019 at 09:29:20PM +0800, lijiang wrote:
>> 在 2019年09月03日 22:37, Simon Horman 写道:
>>> On Wed, Aug 28, 2019 at 05:18:58PM +0800, lijiang wrote:
>>>> Hi, Simon and other reviewers, any comment about v2?
>>>
>>> Hi,
>>>
>>> sorry for the extended delay.
>>> I will look over this.
>>>
>> Never mind. Any suggestions will be appreciated.
>>
>> Thank you in advance.
> 
> Sorry once again for the delay.
> 
> I have applied this series.
> 
OK, thank you, Simon.

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec