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Kernel: Actually set physical base pointer correctly in prekernel stage

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I did a mistake and set the kernel_physical_base value to be just on
the actual linked kernel ELF start offset, while this value should
represent together with KERNEL_MAPPING_BASE the actual higher-half load
address.

By changing this value, we resolve a bug in which disabling KASLR
doesn't work and will cause the prekernel to hang on this statement:
```c++
VERIFY(kernel_load_base >= kernel_mapping_base + 0x200000);
```
This commit is contained in:
Liav A. 2024-05-22 22:03:07 +03:00 committed by Tim Schumacher
parent 899c38d342
commit 3ba5daeca9
Notes: sideshowbarker 2024-07-18 03:20:18 +09:00 
Author: https://github.com/supercomputer7
Commit: https://github.com/SerenityOS/serenity/commit/3ba5daeca9
Pull-request: https://github.com/SerenityOS/serenity/pull/24415
Issue: https://github.com/SerenityOS/serenity/issues/24395
Reviewed-by: https://github.com/timschumi ✅
1 changed files with 2 additions and 2 deletions
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4
Kernel/Prekernel/init.cpp
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@ -116,7 +116,7 @@ extern "C" [[noreturn]] void init()
halt();
__builtin_memcpy(kernel_program_headers, kernel_image + kernel_elf_header.e_phoff, sizeof(Elf_Phdr) * kernel_elf_header.e_phnum);
FlatPtr kernel_physical_base = (FlatPtr)kernel_image;
FlatPtr kernel_physical_base = (FlatPtr)0x200000;
FlatPtr default_kernel_load_base = KERNEL_MAPPING_BASE + kernel_physical_base;
FlatPtr kernel_load_base = default_kernel_load_base;
@ -153,7 +153,7 @@ extern "C" [[noreturn]] void init()
FlatPtr kernel_mapping_base = kernel_load_base & ~(FlatPtr)0x3fffffff;
VERIFY(kernel_load_base % 0x1000 == 0);
VERIFY(kernel_load_base >= kernel_mapping_base + 0x200000);
VERIFY(kernel_load_base >= kernel_mapping_base + kernel_physical_base);
int pdpt_flags = 0x3;