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Kernel: Validate changed framebuffer resolution

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Now we check before we set a FBResolution if the BXVGA device is capable
of setting the requested resolution.
If not, we revert the resolution to the previous one and return an error
to userspace.

Fixes #451.
This commit is contained in:
Liav A 2020-02-26 18:56:58 +02:00 committed by Andreas Kling
parent f14c5b29b4
commit 8dbd1cb9fb
Notes: sideshowbarker 2024-07-19 08:59:42 +09:00 
Author: https://github.com/supercomputer7
Commit: https://github.com/SerenityOS/serenity/commit/8dbd1cb9fb2
Pull-request: https://github.com/SerenityOS/serenity/pull/1316
Issue: https://github.com/SerenityOS/serenity/issues/451
Reviewed-by: https://github.com/Quaker762
Reviewed-by: https://github.com/awesomekling ✅
2 changed files with 76 additions and 7 deletions
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74
Kernel/Devices/BXVGADevice.cpp
View file

@ -64,9 +64,19 @@ BXVGADevice& BXVGADevice::the()
BXVGADevice::BXVGADevice()
: BlockDevice(29, 0)
{
s_the = this;
m_framebuffer_address = PhysicalAddress(find_framebuffer_address());
set_safe_resolution();
}
void BXVGADevice::set_safe_resolution()
{
m_framebuffer_width = 1024;
m_framebuffer_height = 768;
m_framebuffer_pitch = m_framebuffer_width * sizeof(u32);
set_resolution(m_framebuffer_width, m_framebuffer_height);
}
void BXVGADevice::set_register(u16 index, u16 data)
@ -75,12 +85,23 @@ void BXVGADevice::set_register(u16 index, u16 data)
IO::out16(VBE_DISPI_IOPORT_DATA, data);
}
void BXVGADevice::set_resolution(int width, int height)
u16 BXVGADevice::get_register(u16 index)
{
m_framebuffer_pitch = width * sizeof(u32);
m_framebuffer_width = width;
m_framebuffer_height = height;
IO::out16(VBE_DISPI_IOPORT_INDEX, index);
return IO::in16(VBE_DISPI_IOPORT_DATA);
}
void BXVGADevice::revert_resolution()
{
set_resolution_registers(m_framebuffer_width, m_framebuffer_height);
ASSERT(validate_setup_resolution(m_framebuffer_width, m_framebuffer_height));
}
void BXVGADevice::set_resolution_registers(int width, int height)
{
#ifdef BXVGA_DEBUG
dbg() << "BXVGADevice resolution registers set to - " << width << "x" << height;
#endif
set_register(VBE_DISPI_INDEX_ENABLE, VBE_DISPI_DISABLED);
set_register(VBE_DISPI_INDEX_XRES, (u16)width);
set_register(VBE_DISPI_INDEX_YRES, (u16)height);
@ -89,8 +110,38 @@ void BXVGADevice::set_resolution(int width, int height)
set_register(VBE_DISPI_INDEX_BPP, 32);
set_register(VBE_DISPI_INDEX_ENABLE, VBE_DISPI_ENABLED | VBE_DISPI_LFB_ENABLED);
set_register(VBE_DISPI_INDEX_BANK, 0);
}
dbg() << "BXVGADevice resolution set to " << m_framebuffer_width << "x" << m_framebuffer_height << " (pitch=" << m_framebuffer_pitch << ")";
bool BXVGADevice::test_resolution(int width, int height)
{
#ifdef BXVGA_DEBUG
dbg() << "BXVGADevice resolution test - " << width << "x" << height;
#endif
set_resolution_registers(width, height);
bool resolution_changed = validate_setup_resolution(width, height);
revert_resolution();
return resolution_changed;
}
bool BXVGADevice::set_resolution(int width, int height)
{
if (!test_resolution(width, height))
return false;
set_resolution_registers(width, height);
dbg() << "BXVGADevice resolution set to " << width << "x" << height << " (pitch=" << m_framebuffer_pitch << ")";
m_framebuffer_width = width;
m_framebuffer_height = height;
m_framebuffer_pitch = width * sizeof(u32);
return true;
}
bool BXVGADevice::validate_setup_resolution(int width, int height)
{
if ((u16)width != get_register(VBE_DISPI_INDEX_XRES) || (u16)height != get_register(VBE_DISPI_INDEX_YRES)) {
return false;
}
return true;
}
void BXVGADevice::set_y_offset(int y_offset)
@ -174,7 +225,18 @@ int BXVGADevice::ioctl(FileDescription&, unsigned request, unsigned arg)
return -EFAULT;
if (resolution->width > MAX_RESOLUTION_WIDTH || resolution->height > MAX_RESOLUTION_HEIGHT)
return -EINVAL;
set_resolution(resolution->width, resolution->height);
if (!set_resolution(resolution->width, resolution->height)) {
#ifdef BXVGA_DEBUG
dbg() << "Reverting Resolution: [" << m_framebuffer_width << "x" << m_framebuffer_height << "]";
#endif
resolution->pitch = m_framebuffer_pitch;
resolution->width = m_framebuffer_width;
resolution->height = m_framebuffer_height;
return -EINVAL;
}
#ifdef BXVGA_DEBUG
dbg() << "New resolution: [" << m_framebuffer_width << "x" << m_framebuffer_height << "]";
#endif
resolution->pitch = m_framebuffer_pitch;
resolution->width = m_framebuffer_width;
resolution->height = m_framebuffer_height;

9
Kernel/Devices/BXVGADevice.h
View file

@ -52,10 +52,17 @@ private:
virtual bool read_blocks(unsigned, u16, u8*) override { return false; }
virtual bool write_blocks(unsigned, u16, const u8*) override { return false; }
void set_safe_resolution();
void set_register(u16 index, u16 value);
u16 get_register(u16 index);
bool validate_setup_resolution(int width, int height);
u32 find_framebuffer_address();
void revert_resolution();
bool test_resolution(int width, int height);
size_t framebuffer_size_in_bytes() const { return m_framebuffer_pitch * m_framebuffer_height * 2; }
void set_resolution(int width, int height);
bool set_resolution(int width, int height);
void set_resolution_registers(int width, int height);
void set_y_offset(int);
PhysicalAddress m_framebuffer_address;