Hi,
we came across two functions (read/write) that are defined in the l4 base API documentation:
https://os.inf.tu-dresden.de/L4Re/doc/group__l4__mem__op__api.html
1) What does the description "functionality to access user task memory from the kernel" mean? This could be interpreted as accessing user-space memory from within the kernel?!
2) Are there any equivalent memory read/write functions inside the l4re that also take a virtual address as a parameter?
To clarify, all intended operations (read/write) should not modify user-space memory from inside the kernel or vice versa. User-space defined read/write functions should operate in user-space exclusively.
Best Daniel
On 14.02.2017 23:29, Adam Lackorzynski wrote:
Hi,
On Tue Feb 14, 2017 at 10:38:26 +0100, Daniel Krefft wrote:
while working on a checkpoint/restore mechanism for fiasco.oc, we want to trace read and write (kernel) calls to (virtual) memory.
- Where are these calls defined? We're just able to find ARM specific
calls inside the kernel, which allow writing and reading to/from a virtual address
- Are these calls (if existent) platform agnostic (user-space)? Is
there any kind of interface?
I do not quite get the question. The kernel (Fiasco) is running in virtual memory, also when running in the kernel, i.e. any load/store operation that is in the code is through virtual memory. Do you want to trace any read/write issued by the kernel to user-level memory? I'm afraid, the kernel does not do that, i.e. it never touches user-level memory (except the specially treated UTCB memory). Could you please describe your question more verbosely?
Adam
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