Commit d12e4fdd authored by Jarred White's avatar Jarred White Committed by liwei
Browse files

ACPI: CPPC: Fix bit_offset shift in MASK_VAL() macro 

mainline inclusion
from mainline-v6.9-rc6
commit 05d92ee782eeb7b939bdd0189e6efcab9195bf95
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9QRD6
CVE: CVE-2024-35995

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=05d92ee782eeb7b939bdd0189e6efcab9195bf95



--------------------------------

Commit 2f4a4d63a193 ("ACPI: CPPC: Use access_width over bit_width for
system memory accesses") neglected to properly wrap the bit_offset shift
when it comes to applying the mask. This may cause incorrect values to be
read and may cause the cpufreq module not be loaded.

[   11.059751] cpu_capacity: CPU0 missing/invalid highest performance.
[   11.066005] cpu_capacity: partial information: fallback to 1024 for all CPUs

Also, corrected the bitmask generation in GENMASK (extra bit being added).

Fixes: 2f4a4d63a193 ("ACPI: CPPC: Use access_width over bit_width for system memory accesses")
Signed-off-by: default avatarJarred White <jarredwhite@linux.microsoft.com>
Cc: 5.15+ <stable@vger.kernel.org> # 5.15+
Reviewed-by: default avatarVanshidhar Konda <vanshikonda@os.amperecomputing.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarliwei <liwei728@huawei.com>
parent e2cb873b

drivers/acpi/cppc_acpi.c

+2 −2
Original line number Diff line number Diff line
@@ -168,8 +168,8 @@ show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, wraparound_time); 
#define GET_BIT_WIDTH(reg) ((reg)->access_width ? (8 << ((reg)->access_width - 1)) : (reg)->bit_width)



/* Shift and apply the mask for CPC reads/writes */

#define MASK_VAL(reg, val) ((val) >> ((reg)->bit_offset & 			\

					GENMASK(((reg)->bit_width), 0)))

#define MASK_VAL(reg, val) (((val) >> (reg)->bit_offset) & 			\

					GENMASK(((reg)->bit_width) - 1, 0))



static ssize_t show_feedback_ctrs(struct kobject *kobj,

		struct kobj_attribute *attr, char *buf)