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X-MS-Exchange-CrossTenant-Network-Message-Id: a11a03d9-72af-4595-58a6-08ddb908c2ee X-MS-Exchange-CrossTenant-AuthSource: BYAPR11MB3320.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Jul 2025 01:35:44.0810 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: uI0geCL5lFctz2hsE2IgUI8Sezf4xokPUqbKpYMwmhqpsMP1JB4YUuWPG3bIt2T74AcPzTVh5iqpCDwo+WSRoQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR11MB7833 X-OriginatorOrg: intel.com X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 75418160007 X-Stat-Signature: yr6wd53q7gu1mzcsr41314kjxszippp1 X-Rspam-User: X-HE-Tag: 1751420194-654361 X-HE-Meta: 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 /X4bvNmZ 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Shutemov wrote: > LASS throws a #GP for any violations except for stack register accesses, > in which case it throws a #SS instead. Handle this similarly to how other > LASS violations are handled. > Maybe I've misunderstood something: Is the underlying assumption here that #SS were previously only generated by userspace, but now they can also be generated by the kernel? And we want the kernel generated #SS to behave the same as the #GP? > In case of FRED, before handling #SS as LASS violation, kernel has to > check if there's a fixup for the exception. It can address #SS due to > invalid user context on ERETU. See 5105e7687ad3 ("x86/fred: Fixup > fault on ERETU by jumping to fred_entrypoint_user") for more details. > > Co-developed-by: Alexander Shishkin > Signed-off-by: Alexander Shishkin > Signed-off-by: Kirill A. Shutemov > --- > arch/x86/kernel/traps.c | 39 +++++++++++++++++++++++++++++++++------ > 1 file changed, 33 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > index ceb091f17a5b..f9ca5b911141 100644 > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -418,12 +418,6 @@ DEFINE_IDTENTRY_ERRORCODE(exc_segment_not_present) > SIGBUS, 0, NULL); > } > > -DEFINE_IDTENTRY_ERRORCODE(exc_stack_segment) > -{ > - do_error_trap(regs, error_code, "stack segment", X86_TRAP_SS, SIGBUS, > - 0, NULL); > -} > - > DEFINE_IDTENTRY_ERRORCODE(exc_alignment_check) > { > char *str = "alignment check"; > @@ -866,6 +860,39 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection) > cond_local_irq_disable(regs); > } > > +#define SSFSTR "stack segment fault" > + > +DEFINE_IDTENTRY_ERRORCODE(exc_stack_segment) > +{ > + if (user_mode(regs)) > + goto error_trap; > + > + if (cpu_feature_enabled(X86_FEATURE_FRED) && > + fixup_exception(regs, X86_TRAP_SS, error_code, 0)) > + return; > + > + if (cpu_feature_enabled(X86_FEATURE_LASS)) { > + enum kernel_exc_hint hint; > + unsigned long exc_addr; > + > + hint = get_kernel_exc_address(regs, &exc_addr); > + if (hint != EXC_NO_HINT) { The brackets are not needed for singular statements. Also the max line length is longer now. You can fit this all in a single line. > + printk(SSFSTR ", %s 0x%lx", kernel_exc_hint_help[hint], > + exc_addr); > + } > + > + if (hint != EXC_NON_CANONICAL) > + exc_addr = 0; > + > + die_addr(SSFSTR, regs, error_code, exc_addr); The variable names in die_addr() should be generalized as well. They seem to assume the caller to be a #GP handler. > + return; > + } > + > +error_trap: > + do_error_trap(regs, error_code, "stack segment", X86_TRAP_SS, SIGBUS, > + 0, NULL); > +} > + > static bool do_int3(struct pt_regs *regs) > { > int res;