RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-10-31 17:12:43 +00:00
Code Issues Activity Actions

Kernel: Clean up the page fault handling code a bit

Browse source 
Not using "else" after "return" unnests the code and makes it easier to
follow. Also use an enum for the two different page fault types.
This commit is contained in:
Andreas Kling 2019-08-06 09:33:35 +02:00
parent f58b0c245d
commit af4cf01560
2 changed files with 22 additions and 19 deletions
Download patch file Download diff file Expand all files Collapse all files

7
Kernel/Arch/i386/CPU.h
View file

@ -303,9 +303,16 @@ public:
{
}
enum class Type {
PageNotPresent,
ProtectionViolation,
};
VirtualAddress vaddr() const { return m_vaddr; }
u16 code() const { return m_code; }
Type type() const { return (Type)(m_code & 1); }
bool is_not_present() const { return (m_code & 1) == PageFaultFlags::NotPresent; }
bool is_protection_violation() const { return (m_code & 1) == PageFaultFlags::ProtectionViolation; }
bool is_read() const { return (m_code & 2) == PageFaultFlags::Read; }

34
Kernel/VM/MemoryManager.cpp
View file

@ -405,7 +405,7 @@ PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
dbgprintf("MM: handle_page_fault(%w) at L%x\n", fault.code(), fault.vaddr().get());
#endif
ASSERT(fault.vaddr() != m_quickmap_addr);
if (fault.is_not_present() && fault.vaddr().get() >= 0xc0000000) {
if (fault.type() == PageFault::Type::PageNotPresent && fault.vaddr().get() >= 0xc0000000) {
u32 page_directory_index = (fault.vaddr().get() >> 22) & 0x3ff;
auto& kernel_pde = kernel_page_directory().entries()[page_directory_index];
if (kernel_pde.is_present()) {
@ -422,34 +422,30 @@ PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
return PageFaultResponse::ShouldCrash;
}
auto page_index_in_region = region->page_index_from_address(fault.vaddr());
if (fault.is_not_present()) {
if (fault.type() == PageFault::Type::PageNotPresent) {
if (region->vmo().inode()) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("NP(inode) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
page_in_from_inode(*region, page_index_in_region);
return PageFaultResponse::Continue;
} else {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("NP(zero) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
zero_page(*region, page_index_in_region);
return PageFaultResponse::Continue;
}
} else if (fault.is_protection_violation()) {
if (region->should_cow(page_index_in_region)) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("PV(cow) fault in Region{%p}[%u]\n", region, page_index_in_region);
dbgprintf("NP(zero) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
bool success = copy_on_write(*region, page_index_in_region);
ASSERT(success);
return PageFaultResponse::Continue;
}
kprintf("PV(error) fault in Region{%p}[%u] at L%x\n", region, page_index_in_region, fault.vaddr().get());
} else {
ASSERT_NOT_REACHED();
zero_page(*region, page_index_in_region);
return PageFaultResponse::Continue;
}
ASSERT(fault.type() == PageFault::Type::ProtectionViolation);
if (region->should_cow(page_index_in_region)) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("PV(cow) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
bool success = copy_on_write(*region, page_index_in_region);
ASSERT(success);
return PageFaultResponse::Continue;
}
kprintf("PV(error) fault in Region{%p}[%u] at L%x\n", region, page_index_in_region, fault.vaddr().get());
return PageFaultResponse::ShouldCrash;
}