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Merge branch 'spacewander-linux-syscall-3-fix'

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This commit is contained in:
Alexander Kuleshov 2016-10-29 23:16:53 +06:00
commit b1220e3786
2 changed files with 3 additions and 3 deletions
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2
SysCall/syscall-3.md
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@ -180,7 +180,7 @@ All virtual system call requests will fall into the `__vsyscall_page` + `VSYSCAL
In the second case, if we pass `vsyscall=emulate` parameter to the kernel command line, an attempt to perform virtual system call handler will cause a [page fault](https://en.wikipedia.org/wiki/Page_fault) exception. Of course, remember, the `vsyscall` page has `__PAGE_KERNEL_VVAR` access rights that forbid execution. The `do_page_fault` function is the `#PF` or page fault handler. It tries to understand the reason of the last page fault. And one of the reason can be situation when virtual system call called and `vsyscall` mode is `emulate`. In this case `vsyscall` will be handled by the `emulate_vsyscall` function that defined in the [arch/x86/entry/vsyscall/vsyscall_64.c](https://github.com/torvalds/linux/blob/master/arch/x86/entry/vsyscall/vsyscall_64.c) source code file. In the second case, if we pass `vsyscall=emulate` parameter to the kernel command line, an attempt to perform virtual system call handler will cause a [page fault](https://en.wikipedia.org/wiki/Page_fault) exception. Of course, remember, the `vsyscall` page has `__PAGE_KERNEL_VVAR` access rights that forbid execution. The `do_page_fault` function is the `#PF` or page fault handler. It tries to understand the reason of the last page fault. And one of the reason can be situation when virtual system call called and `vsyscall` mode is `emulate`. In this case `vsyscall` will be handled by the `emulate_vsyscall` function that defined in the [arch/x86/entry/vsyscall/vsyscall_64.c](https://github.com/torvalds/linux/blob/master/arch/x86/entry/vsyscall/vsyscall_64.c) source code file.
The `emulate_vsyscall` function gets the number of a virtual system call, checks it, prints error and sends [segmentation fault](https://en.wikipedia.org/wiki/Segmentation_fault) single: The `emulate_vsyscall` function gets the number of a virtual system call, checks it, prints error and sends [segmentation fault](https://en.wikipedia.org/wiki/Segmentation_fault) simply:
```C ```C
... ...

4
SysCall/syscall-4.md
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@ -249,7 +249,7 @@ And set the pointer to the top of new program's stack that we set in the `bprm_m
bprm->exec = bprm->p; bprm->exec = bprm->p;
``` ```
The top of the stack will contain the program filename and we store this filename to the `exec` field of the `linux_bprm` structure. The top of the stack will contain the program filename and we store this fileneme to the `exec` field of the `linux_bprm` structure.
Now we have filled `linux_bprm` structure, we call the `exec_binprm` function: Now we have filled `linux_bprm` structure, we call the `exec_binprm` function:
@ -284,7 +284,7 @@ function. This function goes through the list of handlers that contains differen
* `binfmt_elf_fdpic` - Support for [elf](https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) [FDPIC](http://elinux.org/UClinux_Shared_Library#FDPIC_ELF) binaries; * `binfmt_elf_fdpic` - Support for [elf](https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) [FDPIC](http://elinux.org/UClinux_Shared_Library#FDPIC_ELF) binaries;
* `binfmt_em86` - support for Intel [elf](https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) binaries running on [Alpha](https://en.wikipedia.org/wiki/DEC_Alpha) machines. * `binfmt_em86` - support for Intel [elf](https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) binaries running on [Alpha](https://en.wikipedia.org/wiki/DEC_Alpha) machines.
So, the search_binary_handler tries to call the `load_binary` function and pass `linux_binprm` to it. If the binary handler supports the given executable file format, it starts to prepare the executable binary for execution: So, the `search_binary_handler` tries to call the `load_binary` function and pass `linux_binprm` to it. If the binary handler supports the given executable file format, it starts to prepare the executable binary for execution:
```C ```C
int search_binary_handler(struct linux_binprm *bprm) int search_binary_handler(struct linux_binprm *bprm)