[RFC PATCH 2/7] x86/entry: Add IST main stack

Lai Jiangshan
2023-04-03T14:05:43Z

From: Lai Jiangshan <jiangshan.ljs@antgroup.com>

Add IST main stack for atomic-IST-entry.

The size is THREAD_SIZE since there might be multiple super
exceptions being handled on the stack.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
Documentation/x86/kernel-stacks.rst | 2 ++
arch/x86/include/asm/cpu_entry_area.h | 5 +++++
arch/x86/kernel/dumpstack_64.c | 6 ++++--
arch/x86/mm/cpu_entry_area.c | 1 +
4 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/Documentation/x86/kernel-stacks.rst b/Documentation/x86/kernel-stacks.rst
index 6b0bcf027ff1..be89acf302da 100644
--- a/Documentation/x86/kernel-stacks.rst
+++ b/Documentation/x86/kernel-stacks.rst
@@ -105,6 +105,8 @@ The currently assigned IST stacks are:
middle of switching stacks. Using IST for MCE events avoids making
assumptions about the previous state of the kernel stack.

+* ESTACK_IST. bla bla
+
For more details see the Intel IA32 or AMD AMD64 architecture manuals.

diff --git a/arch/x86/include/asm/cpu_entry_area.h b/arch/x86/include/asm/cpu_entry_area.h
index 462fc34f1317..a373e8c37e25 100644
--- a/arch/x86/include/asm/cpu_entry_area.h
+++ b/arch/x86/include/asm/cpu_entry_area.h
@@ -10,6 +10,8 @@

#ifdef CONFIG_X86_64

+#define IST_MAIN_STKSZ THREAD_SIZE
+
#ifdef CONFIG_AMD_MEM_ENCRYPT
#define VC_EXCEPTION_STKSZ EXCEPTION_STKSZ
#else
@@ -30,6 +32,8 @@
char VC_stack[optional_stack_size]; \
char VC2_stack_guard[guardsize]; \
char VC2_stack[optional_stack_size]; \
+ char IST_stack_guard[guardsize]; \
+ char IST_stack[IST_MAIN_STKSZ]; \
char IST_top_guard[guardsize]; \

/* The exception stacks' physical storage. No guard pages required */
@@ -52,6 +56,7 @@ enum exception_stack_ordering {
ESTACK_MCE,
ESTACK_VC,
ESTACK_VC2,
+ ESTACK_IST,
N_EXCEPTION_STACKS
};

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index f05339fee778..3413b23fa9f1 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -26,11 +26,12 @@ static const char * const exception_stack_names[] = {
[ ESTACK_MCE ] = "#MC",
[ ESTACK_VC ] = "#VC",
[ ESTACK_VC2 ] = "#VC2",
+ [ ESTACK_IST ] = "#IST",
};

const char *stack_type_name(enum stack_type type)
{
- BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
+ BUILD_BUG_ON(N_EXCEPTION_STACKS != ARRAY_SIZE(exception_stack_names));

if (type == STACK_TYPE_TASK)
return "TASK";
@@ -89,6 +90,7 @@ struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = {
EPAGERANGE(MCE),
EPAGERANGE(VC),
EPAGERANGE(VC2),
+ EPAGERANGE(IST),
};

static __always_inline bool in_exception_stack(unsigned long *stack, struct stack_info *info)
@@ -98,7 +100,7 @@ static __always_inline bool in_exception_stack(unsigned long *stack, struct stac
struct pt_regs *regs;
unsigned int k;

- BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
+ BUILD_BUG_ON(N_EXCEPTION_STACKS != 7);

begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
/*
diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c
index 7316a8224259..62341cb819ab 100644
--- a/arch/x86/mm/cpu_entry_area.c
+++ b/arch/x86/mm/cpu_entry_area.c
@@ -148,6 +148,7 @@ static void __init percpu_setup_exception_stacks(unsigned int cpu)
cea_map_stack(NMI);
cea_map_stack(DB);
cea_map_stack(MCE);
+ cea_map_stack(IST);

if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) {
--
2.19.1.6.gb485710b