On 2024-11-26 at 09:34:36 -0700, Shuah Khan wrote: >On 11/26/24 06:34, Maciej Wieczor-Retman wrote: >> Recent change in how get_user() handles pointers [1] has a specific case >> for LAM. It assigns a different bitmask that's later used to check >> whether a pointer comes from userland in get_user(). >> >> While currently commented out (until LASS [2] is merged into the kernel) >> it's worth making changes to the LAM selftest ahead of time. >> >> Modify cpu_has_la57() so it provides current paging level information >> instead of the cpuid one. >> >> Add test case to LAM that utilizes a ioctl (FIOASYNC) syscall which uses >> get_user() in its implementation. Execute the syscall with differently >> tagged pointers to verify that valid user pointers are passing through >> and invalid kernel/non-canonical pointers are not. >> >> Also to avoid unhelpful test failures add a check in main() to skip >> running tests if LAM was not compiled into the kernel. >> >> Code was tested on a Sierra Forest Xeon machine that's LAM capable. The >> test was ran without issues with both the LAM lines from [1] untouched >> and commented out. The test was also ran without issues with LAM_SUP >> both enabled and disabled. >> >> 4/5 level pagetables code paths were also successfully tested in Simics >> on a 5-level capable machine. >> >> [1] https://lore.kernel.org/all/20241024013214.129639-1-torvalds@xxxxxxxxxxxxxxxxxxxx/ >> [2] https://lore.kernel.org/all/20241028160917.1380714-1-alexander.shishkin@xxxxxxxxxxxxxxx/ >> >> Maciej Wieczor-Retman (3): >> selftests/lam: Move cpu_has_la57() to use cpuinfo flag >> selftests/lam: Skip test if LAM is disabled >> selftests/lam: Test get_user() LAM pointer handling >> >> tools/testing/selftests/x86/lam.c | 122 ++++++++++++++++++++++++++++-- >> 1 file changed, 117 insertions(+), 5 deletions(-) >> > >Looks good to me. For selftests if it is going through x86 tree. > >Acked-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> > >If you want me to take this through selftest tree, I can do that. > >thanks, >-- Shuah Thank you, yes, that'd be great! I also just resent v5 [1] fixing the small mistake that Kirill pointed out in "selftests/lam: Move cpu_has_la57() to use cpuinfo flag" [2]. Could you please pull that fixed version? [1] https://lore.kernel.org/all/cover.1732728879.git.maciej.wieczor-retman@xxxxxxxxx/ [2] https://lore.kernel.org/all/6kfafs7wio7ruth3p54pezqwcultxqqpnjvehjzaz7hlba4rp3@6kb5zdqfglsl/ -- Kind regards Maciej Wieczór-Retman
