Bug 199740
| Summary: | syscall __clear_cache (ARM_SYNC_ICACHE) does not achieve icache consistency | ||
|---|---|---|---|
| Product: | Base System | Reporter: | weiss |
| Component: | arm | Assignee: | freebsd-arm (Nobody) <freebsd-arm> |
| Status: | Closed FIXED | ||
| Severity: | Affects Some People | CC: | ian |
| Priority: | --- | ||
| Version: | CURRENT | ||
| Hardware: | Any | ||
| OS: | Any | ||
The ARM ARM, in a rare example of lucidity, describes the register parameter for cp15 cache operations thusly: "When the data is stated to be an MVA, it does not have to be cache line aligned. If these changes lead to something working that doesn't work without the changes, I guess we need to figure out why. It may imply that the caller to the function is incorrectly converting a start/end tulple to start/len or something along those lines. sorry, my bug report was a bit brief.
assume a cache line size of 32 bytes and a call with offset 16 and length 24.
It should sync 2 cache lines but does actually sync only one. The last
8 bytes would not be synced.
So one does not have to round the va to a boundary, but one has to adjust
the length.
So the following change would probably be sufficient (untested)
ENTRY_NP(armv7_icache_sync_range)
ldr ip, .Larmv7_icache_line_size
ldr ip, [ip]
+ sub r3, ip, #1
+ and r2, r0, r3
+ add r1, r1, r2
.Larmv7_sync_next:
mcr CP15_DCCMVAC(r0)
mcr CP15_ICIMVAU(r0)
A commit references this bug: Author: ian Date: Mon May 4 14:55:22 UTC 2015 New revision: 282418 URL: https://svnweb.freebsd.org/changeset/base/282418 Log: On an icache sync by address/len, round the length up if the operation spans a cacheline boundary. PR: 199740 Submitted by: Juergen Weiss <weiss@uni-mainz.de> Changes: head/sys/arm/arm/cpufunc_asm_armv7.S |
function does not round to cache line boundaries as all other functions in this file do diff --git a/sys/arm/arm/cpufunc_asm_armv7.S b/sys/arm/arm/cpufunc_asm_armv7.S index 25f052f..6a9b3e0 100644 --- a/sys/arm/arm/cpufunc_asm_armv7.S +++ b/sys/arm/arm/cpufunc_asm_armv7.S @@ -264,8 +272,14 @@ ENTRY_NP(armv7_icache_sync_all) END(armv7_icache_sync_all) ENTRY_NP(armv7_icache_sync_range) ldr ip, .Larmv7_icache_line_size ldr ip, [ip] + sub r3, ip, #1 + and r2, r0, r3 + add r1, r1, r2 + bic r0, r0, r3 .Larmv7_sync_next: mcr CP15_DCCMVAC(r0) mcr CP15_ICIMVAU(r0)