diff mbox series

[bpf-next,v2,1/2] bpf: Unify data extension operation of jited_ksyms and jited_linfo

Message ID 20220429014240.3434866-2-pulehui@huawei.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series Support riscv jit to provide | expand

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Context Check Description
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 15 this patch: 15
netdev/cc_maintainers success CCed 14 of 14 maintainers
netdev/build_clang success Errors and warnings before: 11 this patch: 11
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 15 this patch: 15
netdev/checkpatch warning CHECK: No space is necessary after a cast
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-VM_Test-1 fail Logs for Kernel LATEST on ubuntu-latest + selftests
bpf/vmtest-bpf-next-PR fail PR summary
bpf/vmtest-bpf-next-VM_Test-2 success Logs for Kernel LATEST on z15 + selftests

Commit Message

Pu Lehui April 29, 2022, 1:42 a.m. UTC
We found that 32-bit environment can not print bpf line info due
to data inconsistency between jited_ksyms[0] and jited_linfo[0].

For example:
jited_kyms[0] = 0xb800067c, jited_linfo[0] = 0xffffffffb800067c

We know that both of them store bpf func address, but due to the
different data extension operations when extended to u64, they may
not be the same. We need to unify the data extension operations of
them.

Signed-off-by: Pu Lehui <pulehui@huawei.com>
---
 kernel/bpf/syscall.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

John Fastabend May 6, 2022, 8:52 p.m. UTC | #1
Pu Lehui wrote:
> We found that 32-bit environment can not print bpf line info due
> to data inconsistency between jited_ksyms[0] and jited_linfo[0].
> 
> For example:
> jited_kyms[0] = 0xb800067c, jited_linfo[0] = 0xffffffffb800067c
> 
> We know that both of them store bpf func address, but due to the
> different data extension operations when extended to u64, they may
> not be the same. We need to unify the data extension operations of
> them.
> 
> Signed-off-by: Pu Lehui <pulehui@huawei.com>
> ---
>  kernel/bpf/syscall.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index e9e3e49c0eb7..18137ea5190d 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -3871,13 +3871,16 @@ static int bpf_prog_get_info_by_fd(struct file *file,
>  		info.nr_jited_line_info = 0;
>  	if (info.nr_jited_line_info && ulen) {
>  		if (bpf_dump_raw_ok(file->f_cred)) {
> +			unsigned long jited_linfo_addr;
>  			__u64 __user *user_linfo;
>  			u32 i;
>  
>  			user_linfo = u64_to_user_ptr(info.jited_line_info);
>  			ulen = min_t(u32, info.nr_jited_line_info, ulen);
>  			for (i = 0; i < ulen; i++) {
> -				if (put_user((__u64)(long)prog->aux->jited_linfo[i],
> +				jited_linfo_addr = (unsigned long)
> +					prog->aux->jited_linfo[i];
> +				if (put_user((__u64) jited_linfo_addr,
>  					     &user_linfo[i]))

the logic is fine but i'm going to nitpick a bit this 4 lines is ugly
just make it slightly longer than 80chars or use a shoarter name? For
example,

			for (i = 0; i < ulen; i++) {
				unsigned long l;

				l = (unsigned long) prog->aux->jited_linfo[i];
				if (put_user((__u64) l, &user_linfo[i]))

is much nicer -- no reason to smash single assignment across multiple
lines. My $.02.

Thanks,
John
Pu Lehui May 7, 2022, 12:51 a.m. UTC | #2
On 2022/5/7 4:52, John Fastabend wrote:
> Pu Lehui wrote:
>> We found that 32-bit environment can not print bpf line info due
>> to data inconsistency between jited_ksyms[0] and jited_linfo[0].
>>
>> For example:
>> jited_kyms[0] = 0xb800067c, jited_linfo[0] = 0xffffffffb800067c
>>
>> We know that both of them store bpf func address, but due to the
>> different data extension operations when extended to u64, they may
>> not be the same. We need to unify the data extension operations of
>> them.
>>
>> Signed-off-by: Pu Lehui <pulehui@huawei.com>
>> ---
>>   kernel/bpf/syscall.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
>> index e9e3e49c0eb7..18137ea5190d 100644
>> --- a/kernel/bpf/syscall.c
>> +++ b/kernel/bpf/syscall.c
>> @@ -3871,13 +3871,16 @@ static int bpf_prog_get_info_by_fd(struct file *file,
>>   		info.nr_jited_line_info = 0;
>>   	if (info.nr_jited_line_info && ulen) {
>>   		if (bpf_dump_raw_ok(file->f_cred)) {
>> +			unsigned long jited_linfo_addr;
>>   			__u64 __user *user_linfo;
>>   			u32 i;
>>   
>>   			user_linfo = u64_to_user_ptr(info.jited_line_info);
>>   			ulen = min_t(u32, info.nr_jited_line_info, ulen);
>>   			for (i = 0; i < ulen; i++) {
>> -				if (put_user((__u64)(long)prog->aux->jited_linfo[i],
>> +				jited_linfo_addr = (unsigned long)
>> +					prog->aux->jited_linfo[i];
>> +				if (put_user((__u64) jited_linfo_addr,
>>   					     &user_linfo[i]))
> 
> the logic is fine but i'm going to nitpick a bit this 4 lines is ugly
> just make it slightly longer than 80chars or use a shoarter name? For
> example,
> 
> 			for (i = 0; i < ulen; i++) {
> 				unsigned long l;
> 
> 				l = (unsigned long) prog->aux->jited_linfo[i];
> 				if (put_user((__u64) l, &user_linfo[i]))
> 
> is much nicer -- no reason to smash single assignment across multiple
> lines. My $.02.
> 

Okay, It sounds good. I will make change in next version. Thanks.

> Thanks,
> John
> .
>
diff mbox series

Patch

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e9e3e49c0eb7..18137ea5190d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3871,13 +3871,16 @@  static int bpf_prog_get_info_by_fd(struct file *file,
 		info.nr_jited_line_info = 0;
 	if (info.nr_jited_line_info && ulen) {
 		if (bpf_dump_raw_ok(file->f_cred)) {
+			unsigned long jited_linfo_addr;
 			__u64 __user *user_linfo;
 			u32 i;
 
 			user_linfo = u64_to_user_ptr(info.jited_line_info);
 			ulen = min_t(u32, info.nr_jited_line_info, ulen);
 			for (i = 0; i < ulen; i++) {
-				if (put_user((__u64)(long)prog->aux->jited_linfo[i],
+				jited_linfo_addr = (unsigned long)
+					prog->aux->jited_linfo[i];
+				if (put_user((__u64) jited_linfo_addr,
 					     &user_linfo[i]))
 					return -EFAULT;
 			}