From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- Documentation/gpu/amdgpu/ptl.rst | 94 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 Documentation/gpu/amdgpu/ptl.rst (limited to 'Documentation/gpu/amdgpu/ptl.rst') diff --git a/Documentation/gpu/amdgpu/ptl.rst b/Documentation/gpu/amdgpu/ptl.rst new file mode 100644 index 000000000..c7f16dea7 --- /dev/null +++ b/Documentation/gpu/amdgpu/ptl.rst @@ -0,0 +1,94 @@ +======================================= +Peak Tops Limiter (PTL) sysfs Interface +======================================= + +Overview +-------- +The Peak Tops Limiter (PTL) sysfs interface enables users to control and +configure the PTL feature for each GPU individually. All PTL-related +sysfs files are located under `/sys/class/drm/cardX/device/ptl/`, where +`X` is the GPU index. Through these files, users can enable or disable +PTL, set preferred data formats, and query supported formats for each GPU. + +PTL sysfs files +---------------- +The following files are available under `/sys/class/drm/cardX/device/ptl/`: + +- `ptl_enable` +- `ptl_format` +- `ptl_supported_formats` + +PTL Enable/Disable +------------------ +File: `ptl_enable` +Type: Read/Write (rw) + +Read: Returns the current PTL status as a string: `enabled` if PTL +is active, or `disabled` if inactive. + +Write: + +- Write `1` or `enabled` to enable PTL +- Write `0` or `disabled` to disable PTL + +Examples:: + + # Query PTL status + cat /sys/class/drm/card1/device/ptl/ptl_enable + # Output: enabled + + # Enable PTL + sudo bash -c "echo 1 > /sys/class/drm/card1/device/ptl/ptl_enable" + + # Disable PTL + sudo bash -c "echo 0 > /sys/class/drm/card1/device/ptl/ptl_enable" + +PTL Format (Preferred Data Formats) +----------------------------------- +File: `ptl_format` +Type: Read/Write (rw) + +Read: Returns the two preferred formats, e.g. `I8,F32`. + +Write: Accepts two formats separated by a comma, e.g. `I8,F32`. + +- Both formats must be supported and different. +- If an invalid format is provided (not supported, or both formats are the + same), the driver will return "write error: Invalid argument". + +Examples:: + + # Query PTL formats + cat /sys/class/drm/card1/device/ptl/ptl_format + # Output: I8,F32 + + # Set PTL formats + sudo bash -c "echo I8,F32 > /sys/class/drm/card1/device/ptl/ptl_format" + +Supported Formats +----------------- +File: `ptl_supported_formats` +Type: Read-only (r) + +Read: Returns a comma-separated list of supported formats, e.g. +`I8,F16,BF16,F32,F64`. + +Example:: + + # Check supported formats + cat /sys/class/drm/card1/device/ptl/ptl_supported_formats + # Output: I8,F16,BF16,F32,F64 + +Behavioral Notes +---------------- +- PTL formats can only be set when PTL is enabled. +- If PTL is disabled, `ptl_format` returns `N/A`. +- Only two formats can be set at a time, and they must be from the supported set and different.. +- All commands support per-GPU targeting. +- Root permission is required to enable/disable PTL or change formats. +- If the hardware does not support PTL, the PTL sysfs directory will not + be created. + +Implementation +-------------- +The PTL sysfs nodes are implemented in `drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c`. -- cgit v1.3.1