What happens whenever there is a segfault in linuxchroot segfaultLinux dmesg errors, motherboard issue?newusers causes segfaultIs there a way to temporarily disable segfault messages in dmesg?How does a Segmentation Fault work under-the-hood?Kernel Oops causing system crash when playing game - nvidia driversDebugging a suspend to ram issue with PM_TRACEDoes hypercall take the same time as a linux system call?How is memory corruption handled by Linux when the process terminates?NetworkManager - segfault
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What happens whenever there is a segfault in linux
chroot segfaultLinux dmesg errors, motherboard issue?newusers causes segfaultIs there a way to temporarily disable segfault messages in dmesg?How does a Segmentation Fault work under-the-hood?Kernel Oops causing system crash when playing game - nvidia driversDebugging a suspend to ram issue with PM_TRACEDoes hypercall take the same time as a linux system call?How is memory corruption handled by Linux when the process terminates?NetworkManager - segfault
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What are the steps that the Linux kernel does whenever the hardware raises segfault. Right now I know that through the IDT, the fault handler handles it, and somewhere along the road there is a message in the kern.log (dmesg) about the fault.
I am asking this question because I am developing an hypervisor, and whenever there is a segfault in user space (which should`nt crash the system), the system crashes (the crash happens only after the message in the kern.log). So if I could retrace what the kernel does whenever it encounters segfault it will help me a lot.
linux linux-kernel x86 segmentation-fault
edited May 2 at 11:01
sourcejedi
27.1k446120
asked May 2 at 4:30
dmgdmg
163
add a comment |
What are the steps that the Linux kernel does whenever the hardware raises segfault. Right now I know that through the IDT, the fault handler handles it, and somewhere along the road there is a message in the kern.log (dmesg) about the fault.
I am asking this question because I am developing an hypervisor, and whenever there is a segfault in user space (which should`nt crash the system), the system crashes (the crash happens only after the message in the kern.log). So if I could retrace what the kernel does whenever it encounters segfault it will help me a lot.
linux linux-kernel x86 segmentation-fault
edited May 2 at 11:01
sourcejedi
27.1k446120
asked May 2 at 4:30
dmgdmg
163
Does you hypervisor run on Linux, or is Linux the guest system? What exactly crashes?
– RalfFriedl
May 2 at 4:59
@RalfFriedl it's a thin hypervisor, so it runs from Linux and make it the guest. The whole setup runs on VMware player, and the whole setup crashes. So somehow the segfault make the hypervisor enters a buggy state, that's why I want to understand what's the process of segfault.
– dmg
May 2 at 5:10
add a comment |
What are the steps that the Linux kernel does whenever the hardware raises segfault. Right now I know that through the IDT, the fault handler handles it, and somewhere along the road there is a message in the kern.log (dmesg) about the fault.
I am asking this question because I am developing an hypervisor, and whenever there is a segfault in user space (which should`nt crash the system), the system crashes (the crash happens only after the message in the kern.log). So if I could retrace what the kernel does whenever it encounters segfault it will help me a lot.
linux linux-kernel x86 segmentation-fault
edited May 2 at 11:01
sourcejedi
27.1k446120
asked May 2 at 4:30
dmgdmg
163
What are the steps that the Linux kernel does whenever the hardware raises segfault. Right now I know that through the IDT, the fault handler handles it, and somewhere along the road there is a message in the kern.log (dmesg) about the fault.
I am asking this question because I am developing an hypervisor, and whenever there is a segfault in user space (which should`nt crash the system), the system crashes (the crash happens only after the message in the kern.log). So if I could retrace what the kernel does whenever it encounters segfault it will help me a lot.
linux linux-kernel x86 segmentation-fault
linux linux-kernel x86 segmentation-fault
edited May 2 at 11:01
sourcejedi
27.1k446120
asked May 2 at 4:30
dmgdmg
163
edited May 2 at 11:01
sourcejedi
27.1k446120
asked May 2 at 4:30
dmgdmg
163
edited May 2 at 11:01
sourcejedi
27.1k446120
edited May 2 at 11:01
sourcejedi
27.1k446120
edited May 2 at 11:01
sourcejedi
27.1k446120
27.1k446120
asked May 2 at 4:30
dmgdmg
163
asked May 2 at 4:30
dmgdmg
163
asked May 2 at 4:30
dmgdmg
163
163
Does you hypervisor run on Linux, or is Linux the guest system? What exactly crashes?
– RalfFriedl
May 2 at 4:59
@RalfFriedl it's a thin hypervisor, so it runs from Linux and make it the guest. The whole setup runs on VMware player, and the whole setup crashes. So somehow the segfault make the hypervisor enters a buggy state, that's why I want to understand what's the process of segfault.
– dmg
May 2 at 5:10
add a comment |
Does you hypervisor run on Linux, or is Linux the guest system? What exactly crashes?
– RalfFriedl
May 2 at 4:59
@RalfFriedl it's a thin hypervisor, so it runs from Linux and make it the guest. The whole setup runs on VMware player, and the whole setup crashes. So somehow the segfault make the hypervisor enters a buggy state, that's why I want to understand what's the process of segfault.
– dmg
May 2 at 5:10
Does you hypervisor run on Linux, or is Linux the guest system? What exactly crashes?
– RalfFriedl
May 2 at 4:59
Does you hypervisor run on Linux, or is Linux the guest system? What exactly crashes?
– RalfFriedl
May 2 at 4:59
@RalfFriedl it's a thin hypervisor, so it runs from Linux and make it the guest. The whole setup runs on VMware player, and the whole setup crashes. So somehow the segfault make the hypervisor enters a buggy state, that's why I want to understand what's the process of segfault.
– dmg
May 2 at 5:10
@RalfFriedl it's a thin hypervisor, so it runs from Linux and make it the guest. The whole setup runs on VMware player, and the whole setup crashes. So somehow the segfault make the hypervisor enters a buggy state, that's why I want to understand what's the process of segfault.
– dmg
May 2 at 5:10
add a comment |
2 Answers
2
active
oldest
votes
arch/x86/kernel/idt.c:152 -page_faultis used in the IDT
arch/x86/entry/entry_64.S:1143 -page_faultis defined as a wrapper function fordo_page_fault(), implemented using the macroidtentry
arch/x86/entry/entry_64.S:847 -idtentrymacro
arch/x86/mm/fault.c:1562 -do_page_fault()
Once you reach do_page_fault(), you should see clickable links to navigate the rest of the code. You can't do that for these first four steps, because Elixir doesn't understand the macro magic. It also doesn't understand assembly.
If you need to look at any other traps, some of the other handler functions (do_*) are in turn defined by another macro, x86/kernel/traps.c:281 DO_ERROR().
The function that logs the segfault message is also in fault.c: show_signal_msg(). A little freebie for you. Elixir doesn't allow searching for strings in general, only identifiers. GitHub also shut down their code search. In any case it's hard to search for this message format string without actually downloading the source code, because "%s%s[%d]: segfault at %lx ip %px sp %px error %lx" does not contain a lot of specific words or phrases :-).
The above links are to specific line numbers of the v5.0 source code. Using Elixir, which I really like :-).
answered May 2 at 10:27
sourcejedisourcejedi
27.1k446120
1
The question doesn't mention Elixir at all though?
– Will
May 2 at 10:58
@Will but I like it, and this answer says you need to click through the links anyway, which will tell you what Elixir is :-). A bit of suspense for you.
– sourcejedi
May 2 at 10:59
add a comment |
The user space is managed and run by the kernel, and thus if a kernel level segfault occur inside the user space it will affect the kernel.
Each system will behave differently according to the log setup, the kernel setup and whether it's using systemd or not (but dmesg is commonly the main debugging/log location)
In your particular situation if you know what process generate the segfault you use strace or gdb appname to debug the problematic process.
https://wiki.archlinux.org/index.php/Step-by-step_debugging_guide this guide have more details about how to debug a segfault
answered May 2 at 9:17
tiff4455 tiff4455
213
As I staated the seg fault occurs at the user space, and I actually raise it on purpose. The thing I am trying to debug is how the default crashes the system through error in a different part of my code, aka the hypervisor. That's why I try to understand what Linux do when segfault .
– dmg
May 2 at 14:58
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
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votes
active
oldest
votes
arch/x86/kernel/idt.c:152 -page_faultis used in the IDT
arch/x86/entry/entry_64.S:1143 -page_faultis defined as a wrapper function fordo_page_fault(), implemented using the macroidtentry
arch/x86/entry/entry_64.S:847 -idtentrymacro
arch/x86/mm/fault.c:1562 -do_page_fault()
Once you reach do_page_fault(), you should see clickable links to navigate the rest of the code. You can't do that for these first four steps, because Elixir doesn't understand the macro magic. It also doesn't understand assembly.
If you need to look at any other traps, some of the other handler functions (do_*) are in turn defined by another macro, x86/kernel/traps.c:281 DO_ERROR().
The function that logs the segfault message is also in fault.c: show_signal_msg(). A little freebie for you. Elixir doesn't allow searching for strings in general, only identifiers. GitHub also shut down their code search. In any case it's hard to search for this message format string without actually downloading the source code, because "%s%s[%d]: segfault at %lx ip %px sp %px error %lx" does not contain a lot of specific words or phrases :-).
The above links are to specific line numbers of the v5.0 source code. Using Elixir, which I really like :-).
answered May 2 at 10:27
sourcejedisourcejedi
27.1k446120
1
The question doesn't mention Elixir at all though?
– Will
May 2 at 10:58
@Will but I like it, and this answer says you need to click through the links anyway, which will tell you what Elixir is :-). A bit of suspense for you.
– sourcejedi
May 2 at 10:59
add a comment |
arch/x86/kernel/idt.c:152 -page_faultis used in the IDT
arch/x86/entry/entry_64.S:1143 -page_faultis defined as a wrapper function fordo_page_fault(), implemented using the macroidtentry
arch/x86/entry/entry_64.S:847 -idtentrymacro
arch/x86/mm/fault.c:1562 -do_page_fault()
Once you reach do_page_fault(), you should see clickable links to navigate the rest of the code. You can't do that for these first four steps, because Elixir doesn't understand the macro magic. It also doesn't understand assembly.
If you need to look at any other traps, some of the other handler functions (do_*) are in turn defined by another macro, x86/kernel/traps.c:281 DO_ERROR().
The function that logs the segfault message is also in fault.c: show_signal_msg(). A little freebie for you. Elixir doesn't allow searching for strings in general, only identifiers. GitHub also shut down their code search. In any case it's hard to search for this message format string without actually downloading the source code, because "%s%s[%d]: segfault at %lx ip %px sp %px error %lx" does not contain a lot of specific words or phrases :-).
The above links are to specific line numbers of the v5.0 source code. Using Elixir, which I really like :-).
answered May 2 at 10:27
sourcejedisourcejedi
27.1k446120
1
The question doesn't mention Elixir at all though?
– Will
May 2 at 10:58
@Will but I like it, and this answer says you need to click through the links anyway, which will tell you what Elixir is :-). A bit of suspense for you.
– sourcejedi
May 2 at 10:59
add a comment |
arch/x86/kernel/idt.c:152 -page_faultis used in the IDT
arch/x86/entry/entry_64.S:1143 -page_faultis defined as a wrapper function fordo_page_fault(), implemented using the macroidtentry
arch/x86/entry/entry_64.S:847 -idtentrymacro
arch/x86/mm/fault.c:1562 -do_page_fault()
Once you reach do_page_fault(), you should see clickable links to navigate the rest of the code. You can't do that for these first four steps, because Elixir doesn't understand the macro magic. It also doesn't understand assembly.
If you need to look at any other traps, some of the other handler functions (do_*) are in turn defined by another macro, x86/kernel/traps.c:281 DO_ERROR().
The function that logs the segfault message is also in fault.c: show_signal_msg(). A little freebie for you. Elixir doesn't allow searching for strings in general, only identifiers. GitHub also shut down their code search. In any case it's hard to search for this message format string without actually downloading the source code, because "%s%s[%d]: segfault at %lx ip %px sp %px error %lx" does not contain a lot of specific words or phrases :-).
The above links are to specific line numbers of the v5.0 source code. Using Elixir, which I really like :-).
answered May 2 at 10:27
sourcejedisourcejedi
27.1k446120
arch/x86/kernel/idt.c:152 -page_faultis used in the IDT
arch/x86/entry/entry_64.S:1143 -page_faultis defined as a wrapper function fordo_page_fault(), implemented using the macroidtentry
arch/x86/entry/entry_64.S:847 -idtentrymacro
arch/x86/mm/fault.c:1562 -do_page_fault()
Once you reach do_page_fault(), you should see clickable links to navigate the rest of the code. You can't do that for these first four steps, because Elixir doesn't understand the macro magic. It also doesn't understand assembly.
If you need to look at any other traps, some of the other handler functions (do_*) are in turn defined by another macro, x86/kernel/traps.c:281 DO_ERROR().
The function that logs the segfault message is also in fault.c: show_signal_msg(). A little freebie for you. Elixir doesn't allow searching for strings in general, only identifiers. GitHub also shut down their code search. In any case it's hard to search for this message format string without actually downloading the source code, because "%s%s[%d]: segfault at %lx ip %px sp %px error %lx" does not contain a lot of specific words or phrases :-).
The above links are to specific line numbers of the v5.0 source code. Using Elixir, which I really like :-).
answered May 2 at 10:27
sourcejedisourcejedi
27.1k446120
edited May 2 at 15:09
answered May 2 at 10:27
sourcejedisourcejedi
27.1k446120
answered May 2 at 10:27
sourcejedisourcejedi
27.1k446120
answered May 2 at 10:27
sourcejedisourcejedi
27.1k446120
27.1k446120
1
The question doesn't mention Elixir at all though?
– Will
May 2 at 10:58
@Will but I like it, and this answer says you need to click through the links anyway, which will tell you what Elixir is :-). A bit of suspense for you.
– sourcejedi
May 2 at 10:59
add a comment |
1
The question doesn't mention Elixir at all though?
– Will
May 2 at 10:58
@Will but I like it, and this answer says you need to click through the links anyway, which will tell you what Elixir is :-). A bit of suspense for you.
– sourcejedi
May 2 at 10:59
1
1
The question doesn't mention Elixir at all though?
– Will
May 2 at 10:58
The question doesn't mention Elixir at all though?
– Will
May 2 at 10:58
@Will but I like it, and this answer says you need to click through the links anyway, which will tell you what Elixir is :-). A bit of suspense for you.
– sourcejedi
May 2 at 10:59
@Will but I like it, and this answer says you need to click through the links anyway, which will tell you what Elixir is :-). A bit of suspense for you.
– sourcejedi
May 2 at 10:59
add a comment |
The user space is managed and run by the kernel, and thus if a kernel level segfault occur inside the user space it will affect the kernel.
Each system will behave differently according to the log setup, the kernel setup and whether it's using systemd or not (but dmesg is commonly the main debugging/log location)
In your particular situation if you know what process generate the segfault you use strace or gdb appname to debug the problematic process.
https://wiki.archlinux.org/index.php/Step-by-step_debugging_guide this guide have more details about how to debug a segfault
answered May 2 at 9:17
tiff4455 tiff4455
213
As I staated the seg fault occurs at the user space, and I actually raise it on purpose. The thing I am trying to debug is how the default crashes the system through error in a different part of my code, aka the hypervisor. That's why I try to understand what Linux do when segfault .
– dmg
May 2 at 14:58
add a comment |
The user space is managed and run by the kernel, and thus if a kernel level segfault occur inside the user space it will affect the kernel.
Each system will behave differently according to the log setup, the kernel setup and whether it's using systemd or not (but dmesg is commonly the main debugging/log location)
In your particular situation if you know what process generate the segfault you use strace or gdb appname to debug the problematic process.
https://wiki.archlinux.org/index.php/Step-by-step_debugging_guide this guide have more details about how to debug a segfault
answered May 2 at 9:17
tiff4455 tiff4455
213
As I staated the seg fault occurs at the user space, and I actually raise it on purpose. The thing I am trying to debug is how the default crashes the system through error in a different part of my code, aka the hypervisor. That's why I try to understand what Linux do when segfault .
– dmg
May 2 at 14:58
add a comment |
The user space is managed and run by the kernel, and thus if a kernel level segfault occur inside the user space it will affect the kernel.
Each system will behave differently according to the log setup, the kernel setup and whether it's using systemd or not (but dmesg is commonly the main debugging/log location)
In your particular situation if you know what process generate the segfault you use strace or gdb appname to debug the problematic process.
https://wiki.archlinux.org/index.php/Step-by-step_debugging_guide this guide have more details about how to debug a segfault
answered May 2 at 9:17
tiff4455 tiff4455
213
The user space is managed and run by the kernel, and thus if a kernel level segfault occur inside the user space it will affect the kernel.
Each system will behave differently according to the log setup, the kernel setup and whether it's using systemd or not (but dmesg is commonly the main debugging/log location)
In your particular situation if you know what process generate the segfault you use strace or gdb appname to debug the problematic process.
https://wiki.archlinux.org/index.php/Step-by-step_debugging_guide this guide have more details about how to debug a segfault
answered May 2 at 9:17
tiff4455 tiff4455
213
answered May 2 at 9:17
tiff4455 tiff4455
213
answered May 2 at 9:17
tiff4455 tiff4455
213
answered May 2 at 9:17
tiff4455 tiff4455
213
213
As I staated the seg fault occurs at the user space, and I actually raise it on purpose. The thing I am trying to debug is how the default crashes the system through error in a different part of my code, aka the hypervisor. That's why I try to understand what Linux do when segfault .
– dmg
May 2 at 14:58
add a comment |
As I staated the seg fault occurs at the user space, and I actually raise it on purpose. The thing I am trying to debug is how the default crashes the system through error in a different part of my code, aka the hypervisor. That's why I try to understand what Linux do when segfault .
– dmg
May 2 at 14:58
As I staated the seg fault occurs at the user space, and I actually raise it on purpose. The thing I am trying to debug is how the default crashes the system through error in a different part of my code, aka the hypervisor. That's why I try to understand what Linux do when segfault .
– dmg
May 2 at 14:58
As I staated the seg fault occurs at the user space, and I actually raise it on purpose. The thing I am trying to debug is how the default crashes the system through error in a different part of my code, aka the hypervisor. That's why I try to understand what Linux do when segfault .
– dmg
May 2 at 14:58
add a comment |
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Does you hypervisor run on Linux, or is Linux the guest system? What exactly crashes?
– RalfFriedl
May 2 at 4:59
@RalfFriedl it's a thin hypervisor, so it runs from Linux and make it the guest. The whole setup runs on VMware player, and the whole setup crashes. So somehow the segfault make the hypervisor enters a buggy state, that's why I want to understand what's the process of segfault.
– dmg
May 2 at 5:10