From: Dave Hansen <dave.hansen@linux.intel.com>
To: linux-kernel@vger.kernel.org
Cc: Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Edgecombe, Rick P <rick.p.edgecombe@intel.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
the arch/x86 maintainers <x86@kernel.org>,
Kees Cook <kees@kernel.org>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Borislav Petkov <bp@alien8.de>, Thomas Gleixner <tglx@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: [RFC][PATCH 09/24] x86/cea: Refactor "CEA" macros to deal with multiple stacks
Date: Wed, 21 Oct 2026 12:51:32 -0700 [thread overview]
Message-ID: <20261021195132.EF14B7C8@davehans-spike.ostc.intel.com> (raw)
In-Reply-To: <20261021195120.E61EC737@davehans-spike.ostc.intel.com>
There are a series of CPU Entry Area (CEA) helper macros to make
it easier to deal with the CEA structure geometry. Right now,
many of them can deal only with the regular stack.
Prepare for shadow stacks by refactoring the macros to take a
(partial) structure member name. For now, that is just "stack".
This is a pure refactoring. No behavioral changes intended.
Nits: CEA_ESTACK_PAGES gets a whitespace change to make it
consistent with the new width of the four related macros above
it. There's also some slight rewrapping of the macros in a place
or two to make them more readable.
---
b/arch/x86/include/asm/cpu_entry_area.h | 23 ++++++++++++-----------
b/arch/x86/kernel/dumpstack_64.c | 9 +++++----
2 files changed, 17 insertions(+), 15 deletions(-)
diff -puN arch/x86/include/asm/cpu_entry_area.h~cea-estacks-shadows arch/x86/include/asm/cpu_entry_area.h
--- a/arch/x86/include/asm/cpu_entry_area.h~cea-estacks-shadows 2026-10-21 12:36:36.741878790 -0700
+++ b/arch/x86/include/asm/cpu_entry_area.h 2026-10-21 12:36:36.746878799 -0700
@@ -55,19 +55,20 @@ enum exception_stack_ordering {
N_EXCEPTION_STACKS
};
-#define CEA_ESTACK_SIZE(st) \
- sizeof(((struct cea_exception_stacks *)0)->st## _stack)
+#define CEA_ESTACK_SIZE(st, member) \
+ sizeof(((struct cea_exception_stacks *)0)->st## _ ##member)
-#define CEA_ESTACK_BOT(ceastp, st) \
- ((unsigned long)&(ceastp)->st## _stack)
+#define CEA_ESTACK_BOT(ceastp, st, member) \
+ ((unsigned long)&(ceastp)->st## _ ##member)
-#define CEA_ESTACK_TOP(ceastp, st) \
- (CEA_ESTACK_BOT(ceastp, st) + CEA_ESTACK_SIZE(st))
+#define CEA_ESTACK_TOP(ceastp, st, member) \
+ (CEA_ESTACK_BOT(ceastp, st, member) + \
+ CEA_ESTACK_SIZE(st, member))
-#define CEA_ESTACK_OFFS(st) \
- offsetof(struct cea_exception_stacks, st## _stack)
+#define CEA_ESTACK_OFFS(st, member) \
+ offsetof(struct cea_exception_stacks, st## _ ##member)
-#define CEA_ESTACK_PAGES \
+#define CEA_ESTACK_PAGES \
(sizeof(struct cea_exception_stacks) / PAGE_SIZE)
#endif
@@ -145,9 +146,9 @@ static __always_inline struct entry_stac
}
#define __this_cpu_ist_top_va(name) \
- CEA_ESTACK_TOP(__this_cpu_read(cea_exception_stacks), name)
+ CEA_ESTACK_TOP(__this_cpu_read(cea_exception_stacks), name, stack)
#define __this_cpu_ist_bottom_va(name) \
- CEA_ESTACK_BOT(__this_cpu_read(cea_exception_stacks), name)
+ CEA_ESTACK_BOT(__this_cpu_read(cea_exception_stacks), name, stack)
#endif
diff -puN arch/x86/kernel/dumpstack_64.c~cea-estacks-shadows arch/x86/kernel/dumpstack_64.c
--- a/arch/x86/kernel/dumpstack_64.c~cea-estacks-shadows 2026-10-21 12:36:36.743878793 -0700
+++ b/arch/x86/kernel/dumpstack_64.c 2026-10-21 12:36:36.746878799 -0700
@@ -69,10 +69,11 @@ struct estack_pages {
};
#define EPAGERANGE(st) \
- [PFN_DOWN(CEA_ESTACK_OFFS(st)) ... \
- PFN_DOWN(CEA_ESTACK_OFFS(st) + CEA_ESTACK_SIZE(st) - 1)] = { \
- .offs = CEA_ESTACK_OFFS(st), \
- .size = CEA_ESTACK_SIZE(st), \
+ [PFN_DOWN(CEA_ESTACK_OFFS(st, stack)) ... \
+ PFN_DOWN(CEA_ESTACK_OFFS(st, stack) + \
+ CEA_ESTACK_SIZE(st, stack) - 1)] = { \
+ .offs = CEA_ESTACK_OFFS(st, stack), \
+ .size = CEA_ESTACK_SIZE(st, stack), \
.type = STACK_TYPE_EXCEPTION + ESTACK_ ##st, }
/*
_
next prev parent reply other threads:[~2026-10-21 19:51 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-21 19:51 [RFC][PATCH 00/24] x86 Kernel Shadow Stacks Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 01/24] kernel/fork: Break out vmap task allocation into helper Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 02/24] kernel/fork: Use sizeof() union instead of TASK_SIZE Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 03/24] kernel/sched: Move thread stack to its own structure Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 04/24] kernel/fork: Allow arch-specific stack initialization Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 05/24] kernel/task: Add shadow stack to thread structure Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 06/24] kernel/task: Add "runtime" check for shadow stack support Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 07/24] kernel/fork: Clear shadow stacks alongside normal stacks Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 08/24] x86/cpu: Add basic x86 kernel shadow stack infrastructure Dave Hansen
2026-10-21 19:51 ` Dave Hansen [this message]
2026-10-21 19:51 ` [RFC][PATCH 10/24] x86/cea: Refactor stack mapping macros Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 11/24] x86/mm: Add kernel shadow stack permission macros Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 12/24] x86/cea: Map and use FRED exception shadow stacks Dave Hansen
2026-10-21 21:40 ` Peter Zijlstra
2026-10-21 22:59 ` Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 13/24] x86/task: Grow thread_union for " Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 14/24] x86/mm: Establish shadow stack permissions in thread mapping Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 15/24] x86/task: Hook up arch hook to detect shadow stack enabling Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 16/24] x86/mm: Kill shadow stack page permission warning Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 17/24] x86/task: Context switch the kernel shadow stack register value Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 18/24] kernel/task: Add a helper to get the thread_union Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 19/24] x86/process: Initialize cloned task shadow stack Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 20/24] x86/entry: Stash kernel SSP on FRED entry Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 21/24] x86/extable: Update shadow stack entry frame during RIP overwrites Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 22/24] kernel/task: Add a helper to locate the top of the shadow stack Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 23/24] x86/entry: Populate FRED register for user=>kernel transitions Dave Hansen
2026-10-21 19:51 ` [RFC][PATCH 24/24] [DO NOT MERGE] x86/shstk: Depend out everything incompatible with kernel shadow stacks Dave Hansen
2026-10-21 21:36 ` [RFC][PATCH 00/24] x86 Kernel Shadow Stacks Peter Zijlstra
2026-10-21 21:53 ` Peter Zijlstra
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