[PATCHv6 13/16] x86/traps: Handle LASS thrown #SS
From: Kirill A. Shutemov <hidden>
Date: 2025-06-20 13:53:53
Also in:
linux-efi, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Alexander Shishkin <alexander.shishkin@linux.intel.com> 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. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Kirill A. Shutemov <redacted> --- arch/x86/kernel/traps.c | 34 ++++++++++++++++++++++++++++------ 1 file changed, 28 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 0f558d3369a3..bd8f7e72b238 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 +860,34 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection) cond_local_irq_disable(regs); } +DEFINE_IDTENTRY_ERRORCODE(exc_stack_segment) +{ + if (cpu_feature_enabled(X86_FEATURE_LASS)) { + enum kernel_gp_hint hint = GP_NO_HINT; + unsigned long gp_addr; + + if (user_mode(regs)) { + gp_user_force_sig_segv(regs, X86_TRAP_GP, error_code, GPFSTR); + return; + } + + hint = get_kernel_gp_address(regs, &gp_addr); + if (hint != GP_NO_HINT) { + printk(GPFSTR ", %s 0x%lx", kernel_gp_hint_help[hint], + gp_addr); + } + + if (hint != GP_NON_CANONICAL) + gp_addr = 0; + + die_addr(GPFSTR, regs, error_code, gp_addr); + return; + } + + do_error_trap(regs, error_code, "stack segment", X86_TRAP_SS, SIGBUS, + 0, NULL); +} + static bool do_int3(struct pt_regs *regs) { int res;
--
2.47.2