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DynamicLoader: Ensure that backtrace computation stops at _start

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If we don't set FP and LR to 0, the Kernel might not stop generating
backtraces when it reaches `_start`'s stack frame, and might continue by
reading garbage memory instead. This leads to a kernel panic, as SafeMem
access faults aren't handled properly in the AArch64 kernel yet.

We might want to ensure that the kernel zeroes out all registers when a
new process is created.
This commit is contained in:
Daniel Bertalan 2023-04-22 17:30:09 +02:00 committed by Andreas Kling
parent ff2fa72e28
commit f18e7659a6
1 changed files with 4 additions and 0 deletions
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4
Userland/DynamicLoader/main.cpp
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@ -63,7 +63,11 @@ void _entry(int, char**, char**) __attribute__((used));
NAKED void _start(int, char**, char**)
{
#if ARCH(AARCH64)
// Make sure backtrace computation stops here by setting FP and LR to 0.
// FIXME: The kernel should ensure that registers are zeroed on program start
asm(
"mov x29, 0\n"
"mov x30, 0\n"
"bl _entry\n");
#else
asm(