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Kernel: Make HPET read_main_counter() atomic with 32 bit main counter

This commit is contained in:
Bananymous 2024-02-23 13:42:04 +02:00
parent 9594ee8e47
commit 59abb5d344
1 changed files with 10 additions and 9 deletions
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19
kernel/kernel/Timer/HPET.cpp
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@ -153,7 +153,7 @@ namespace Kernel
m_is_64bit = regs.capabilities & COUNT_SIZE_CAP; m_is_64bit = regs.capabilities & COUNT_SIZE_CAP;
// Disable main counter and reset value // Disable and reset main counter
regs.configuration.low = regs.configuration.low & ~ENABLE_CNF; regs.configuration.low = regs.configuration.low & ~ENABLE_CNF;
regs.main_counter.high = 0; regs.main_counter.high = 0;
regs.main_counter.low = 0; regs.main_counter.low = 0;
@ -244,27 +244,28 @@ namespace Kernel
if (m_is_64bit) if (m_is_64bit)
return regs.main_counter.full; return regs.main_counter.full;
uint32_t current = regs.main_counter.low; CriticalScope _;
uint64_t wraps = m_32bit_wraps; uint32_t current_low = regs.main_counter.low;
if (current < (uint32_t)m_last_ticks) uint32_t wraps = m_32bit_wraps;
if (current_low < (uint32_t)m_last_ticks)
wraps++; wraps++;
return (wraps << 32) | current; return ((uint64_t)wraps << 32) | current_low;
} }
void HPET::handle_irq() void HPET::handle_irq()
{ {
auto& regs = registers(); auto& regs = registers();
uint64_t current_ticks { 0 }; uint64_t current_ticks;
if (m_is_64bit) if (m_is_64bit)
current_ticks = regs.main_counter.full; current_ticks = regs.main_counter.full;
else else
{ {
uint32_t current = regs.main_counter.low; uint32_t current_low = regs.main_counter.low;
if (current < (uint32_t)m_last_ticks) if (current_low < (uint32_t)m_last_ticks)
m_32bit_wraps++; m_32bit_wraps++;
current_ticks = ((uint64_t)m_32bit_wraps << 32) | current; current_ticks = ((uint64_t)m_32bit_wraps << 32) | current_low;
} }
m_last_ticks = current_ticks; m_last_ticks = current_ticks;