When an attribute group is created with sysfs_create_group() or
sysfs_create_files() the ->sysfs_ops() callback is set to
kobj_sysfs_ops, which sets the ->show() callback to kobj_attr_show().
kobj_attr_show() uses container_of() to get the ->show() callback
from the attribute it was passed, meaning the ->show() callback needs
to be the same type as the ->show() callback in 'struct kobj_attribute'.
However, cur_freq_show() has the type of the ->show() callback in
'struct device_attribute', which causes a CFI violation when opening the
'id' sysfs node under gtidle/freq/throttle. This happens to work because
the layout of 'struct kobj_attribute' and 'struct device_attribute' are
the same, so the container_of() cast happens to allow the ->show()
callback to still work.
Changed the type of cur_freq_show() and few more functions to match the
->show() callback in 'struct kobj_attributes' to resolve the CFI
violation.
CFI failure seen while accessing sysfs files under
/sys/class/drm/card0/device/tile0/gt*/gtidle/*
/sys/class/drm/card0/device/tile0/gt*/freq0/*
/sys/class/drm/card0/device/tile0/gt*/freq0/throttle/*
[ 2599.618075] RIP: 0010:__cfi_cur_freq_show+0xd/0x10 [xe]
[ 2599.624452] Code: 44 c1 44 89 fa e8 03 95 39 f2 48 98 5b 41 5e 41 5f 5d c3 c9
[ 2599.646638] RSP: 0018:ffffbe438ead7d10 EFLAGS: 00010286
[ 2599.652823] RAX: ffff9f7d8b3845d8 RBX: ffff9f7dee8c95d8 RCX: 0000000000000000
[ 2599.661246] RDX: ffff9f7e6f439000 RSI: ffffffffc13ada30 RDI: ffff9f7d975d4b00
[ 2599.669669] RBP: ffffbe438ead7d18 R08: 0000000000001000 R09: ffff9f7e6f439000
[ 2599.678092] R10: 00000000e07304a6 R11: ffffffffc1241ca0 R12: ffffffffb4836ea0
[ 2599.688435] R13: ffff9f7e45fb1180 R14: ffff9f7d975d4b00 R15: ffff9f7e6f439000
[ 2599.696860] FS: 000076b02b66cfc0(0000) GS:ffff9f80ef400000(0000) knlGS:00000
[ 2599.706412] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2599.713196] CR2: 00005f80d94641a9 CR3: 00000001e44ec006 CR4: 0000000100f72ef0
[ 2599.721618] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 2599.730041] DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7: 0000000000000400
[ 2599.738464] PKRU: 55555554
[ 2599.741655] Call Trace:
[ 2599.744541] <TASK>
[ 2599.747017] ? __die_body+0x69/0xb0
[ 2599.751151] ? die+0xa9/0xd0
[ 2599.754548] ? do_trap+0x89/0x160
[ 2599.758476] ? __cfi_cur_freq_show+0xd/0x10 [xe b37985c94829727668bd7c5b33c1]
[ 2599.768315] ? handle_invalid_op+0x69/0x90
[ 2599.773167] ? __cfi_cur_freq_show+0xd/0x10 [xe b37985c94829727668bd7c5b33c1]
[ 2599.783010] ? exc_invalid_op+0x36/0x60
[ 2599.787552] ? fred_hwexc+0x123/0x1a0
[ 2599.791873] ? fred_entry_from_kernel+0x7b/0xd0
[ 2599.797219] ? asm_fred_entrypoint_kernel+0x45/0x70
[ 2599.802976] ? act_freq_show+0x70/0x70 [xe b37985c94829727668bd7c5b33c1d9998]
[ 2599.812301] ? __cfi_cur_freq_show+0xd/0x10 [xe b37985c94829727668bd7c5b33c1]
[ 2599.822137] ? __kmalloc_node_noprof+0x1f3/0x420
[ 2599.827594] ? __kvmalloc_node_noprof+0xcb/0x180
[ 2599.833045] ? kobj_attr_show+0x22/0x40
[ 2599.837571] sysfs_kf_seq_show+0xa8/0x110
[ 2599.842302] kernfs_seq_show+0x38/0x50
Signed-off-by: Jeevaka Prabu Badrappan <jeevaka.badrappan@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://lore.kernel.org/r/20250422171852.85558-1-jeevaka.badrappan@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Other driver code beyond the sysfs interface wants to know about
throttling. So make the query function globally accessible.
v2: Revert include order change (review feedback from Lucas)
v3: Remove '_sysfs' from throttle file names and keep limit query in
the same file rather than moving elsewhere (review feedback from
Rodrigo).
v4: Correct #include while renaming header file (review feedback
from Lucas).
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240518043700.3264362-2-John.C.Harrison@Intel.com
