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kernel: x86: enable writes before patching.

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Follow up for commit a2021292d4.
Binary patching would otherwise fail after the kernel text area
becomes read-only.
This commit is contained in:
Jérôme Duval
2018-01-23 17:59:41 +01:00
parent c8fcb2a04e
commit 34cdda1dd5
1 changed files with 14 additions and 3 deletions
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src/system/kernel/arch/x86/arch_altcodepatch.cpp
+14 -3
View File
@@ -11,7 +11,9 @@
#include <KernelExport.h> #include <KernelExport.h>
#include <elf.h>
#include <kernel.h> #include <kernel.h>
#include <vm_defs.h>
@@ -29,18 +31,27 @@ extern altcodepatch altcodepatch_end;
void void
arch_altcodepatch_replace(uint16 tag, void* newcodepatch, size_t length) arch_altcodepatch_replace(uint16 tag, void* newcodepatch, size_t length)
{ {
uint32 count = 0; uint32 count = 0;
// we need to write to the text area
struct elf_image_info* info = elf_get_kernel_image();
uint32 kernelProtection = B_KERNEL_READ_AREA | B_KERNEL_EXECUTE_AREA;
set_area_protection(info->text_region.id, kernelProtection | B_KERNEL_WRITE_AREA);
for (altcodepatch *patch = &altcodepatch_begin; patch < &altcodepatch_end; for (altcodepatch *patch = &altcodepatch_begin; patch < &altcodepatch_end;
patch++) { patch++) {
if (patch->tag != tag) if (patch->tag != tag)
continue; continue;
addr_t address = KERNEL_LOAD_BASE + patch->kernel_offset; void* address = (void*)(KERNEL_LOAD_BASE + patch->kernel_offset);
if (patch->length < length) if (patch->length < length)
panic("can't copy patch: new code is too long\n"); panic("can't copy patch: new code is too long\n");
memcpy((void*)address, newcodepatch, length); memcpy(address, newcodepatch, length);
count++; count++;
} }
// disable write after patch
set_area_protection(info->text_region.id, kernelProtection);
dprintf("arch_altcodepatch_replace found %d altcodepatches\n", count); dprintf("arch_altcodepatch_replace found %d altcodepatches\n", count);
} }