lib/syscall_shim: Extend prsyscall (print structs, ...) #836

marcrittinghaus · 2023-04-14T16:51:14Z

Prerequisite checklist

Read the contribution guidelines regarding submitting new changes to the project;
Tested your changes against relevant architectures and platforms;
Ran the checkpatch.pl on your commit series before opening this PR;
Updated relevant documentation.

Base target

Architecture(s): [N/A]
Platform(s): [N/A]
Application(s): [N/A]

Additional configuration

Description of changes

This PR adds a number of features to the strace-like printing in lib/syscall_shim (prsyscall). New features are:

Printing of structs

Structs can also be nested. The number and selection of fields that should be printed is specified per struct definition.
Printing of PT_OUT-values only on success
Especially, if structs are printed, it can become confusing (and also cause crashes) if a syscall fails and the uninitialized target struct is printed. The PR changes behavior so that values are only printed on success. On failure, only the type and virtual address are printed.
Add PT_OCTAL
Add 0x prefix for PT_HEX to avoid confusion with decimal values
Add printing for further syscalls and their dependent types

Have fun!

Previously, we are printing buffers and output strings also when the call fails. However, in that case it will usually contain no meaningful value so we reduce trace output by just printing the buffer's target address. Checkpatch-Ignore: COMPLEX_MACRO Checkpatch-Ignore: TRAILING_SEMICOLON Checkpatch-Ignore: DO_WHILE_MACRO_WITH_TRAILING_SEMICOLON Checkpatch-Ignore: MULTISTATEMENT_MACRO_USE_DO_WHILE Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io>

Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io>

There are already types for decimal and hexadecimal printing. This commit adds a type for octals. Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io>

Currently, it is hard to know if a value is a hexadecimal or decimal number if there are no letters in the output. This commit adds the hex prefix 0x to avoid the confusion. Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io>

This commit adds macros for printing selected members of struct types in the prsyscall output just like strace. The PT_STRUCT macro takes the struct's name to form a new parameter type name. The PR_STRUCT macro prints the fields specified in the var args. Nested printing of struct fields members is supported for structs pointers as well as for embedded structs. Whenever fields that are usually pointers (e.g., PT_CHARP or PT_STRUCT) are embedded, the `PT_SVAL` flag must be specified. Checkpatch-Ignore: DO_WHILE_MACRO_WITH_TRAILING_SEMICOLON Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io>

This commit adds a definition of the timespec struct to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io>

razvand

Hi, @marcrittinghaus. I tested it and it works. Please use Add instead of add in one of the commit message you created. Then it's all go.

marcrittinghaus · 2023-04-25T11:35:30Z

@razvand,

thanks for pointing that out. Fixed.

razvand

Thanks, @marcrittinghaus.

Reviewed-by: Razvan Deaconescu razvand@unikraft.io

craciunoiuc

All good here. Thanks!

Reviewed-by: Cezar Craciunoiu cezar.craciunoiu@unikraft.io

This commit adds a definition of the stat struct to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io>

marcrittinghaus · 2023-04-25T12:23:07Z

@craciunoiuc,

Thanks for mentioning the dependency on posix-sysinfo. I made the definition of the utsname struct optional, depending on the inclusion of the library.

craciunoiuc · 2023-04-25T12:27:28Z

oh so you actually fixed it here, whoops, I thought it would be done in another PR

Currently, it is hard to know if a value is a hexadecimal or decimal number if there are no letters in the output. This commit adds the hex prefix 0x to avoid the confusion. Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: #836

This commit adds macros for printing selected members of struct types in the prsyscall output just like strace. The PT_STRUCT macro takes the struct's name to form a new parameter type name. The PR_STRUCT macro prints the fields specified in the var args. Nested printing of struct fields members is supported for structs pointers as well as for embedded structs. Whenever fields that are usually pointers (e.g., PT_CHARP or PT_STRUCT) are embedded, the `PT_SVAL` flag must be specified. Checkpatch-Ignore: DO_WHILE_MACRO_WITH_TRAILING_SEMICOLON Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: #836

This commit adds a definition of the timespec struct to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: #836

This commit adds a definition of the stat struct to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: #836

This commit adds a definition of the utsname struct and the uname syscall to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: #836

This commit adds a definition of the pread64 syscall to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: #836

This commit adds a definition of the (F|R|W|X)_OK flags and the access syscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: #836

Previously, we are printing buffers and output strings also when the call fails. However, in that case it will usually contain no meaningful value so we reduce trace output by just printing the buffer's target address. Checkpatch-Ignore: COMPLEX_MACRO Checkpatch-Ignore: TRAILING_SEMICOLON Checkpatch-Ignore: DO_WHILE_MACRO_WITH_TRAILING_SEMICOLON Checkpatch-Ignore: MULTISTATEMENT_MACRO_USE_DO_WHILE Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836

Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836

There are already types for decimal and hexadecimal printing. This commit adds a type for octals. Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836

Currently, it is hard to know if a value is a hexadecimal or decimal number if there are no letters in the output. This commit adds the hex prefix 0x to avoid the confusion. Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836

This commit adds macros for printing selected members of struct types in the prsyscall output just like strace. The PT_STRUCT macro takes the struct's name to form a new parameter type name. The PR_STRUCT macro prints the fields specified in the var args. Nested printing of struct fields members is supported for structs pointers as well as for embedded structs. Whenever fields that are usually pointers (e.g., PT_CHARP or PT_STRUCT) are embedded, the `PT_SVAL` flag must be specified. Checkpatch-Ignore: DO_WHILE_MACRO_WITH_TRAILING_SEMICOLON Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836

This commit adds a definition of the timespec struct to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836

This commit adds a definition of the stat struct to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836

This commit adds a definition of the utsname struct and the uname syscall to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836

This commit adds a definition of the pread64 syscall to prsyscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836

This commit adds a definition of the (F|R|W|X)_OK flags and the access syscall Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io> Reviewed-by: Razvan Deaconescu <razvand@unikraft.io> Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io> Approved-by: Simon Kuenzer <simon@unikraft.io> Tested-by: Unikraft CI <monkey@unikraft.io> GitHub-Closes: unikraft#836