lkml.org 
[lkml]   [2022]   [Aug]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC PATCH 5/5] x86/entry: Store CPU info on exception entry
Date
From: Ira Weiny <ira.weiny@intel.com>

The CPU information of an exception is useful in determining where bad
CPUs are in a large data center.

Define arch_{save|restore}_auxiliary_pt_regs() and set
ARCH_HAS_PTREGS_AUXILIARY default to yes.

Store the CPU on exception entry and use it later.

Cc: Rik van Riel <riel@surriel.com>
Suggested-by: Borislav Petkov <bp@alien8.de>
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
arch/x86/Kconfig | 2 +-
arch/x86/include/asm/entry-common.h | 12 ++++++++++++
arch/x86/include/asm/ptrace.h | 1 +
arch/x86/mm/fault.c | 4 ++--
4 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b35f6a472e09..707650a6ecb2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1876,7 +1876,7 @@ config X86_INTEL_MEMORY_PROTECTION_KEYS

config ARCH_HAS_PTREGS_AUXILIARY
depends on X86_64
- bool
+ def_bool y

choice
prompt "TSX enable mode"
diff --git a/arch/x86/include/asm/entry-common.h b/arch/x86/include/asm/entry-common.h
index 674ed46d3ced..eb145106929a 100644
--- a/arch/x86/include/asm/entry-common.h
+++ b/arch/x86/include/asm/entry-common.h
@@ -95,4 +95,16 @@ static __always_inline void arch_exit_to_user_mode(void)
}
#define arch_exit_to_user_mode arch_exit_to_user_mode

+#ifdef CONFIG_ARCH_HAS_PTREGS_AUXILIARY
+
+static inline void arch_save_aux_pt_regs(struct pt_regs *regs)
+{
+ struct pt_regs_auxiliary *aux_pt_regs = &to_extended_pt_regs(regs)->aux;
+
+ aux_pt_regs->cpu = raw_smp_processor_id();
+}
+#define arch_save_aux_pt_regs arch_save_aux_pt_regs
+
+#endif
+
#endif
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 5a9c85893459..b403b469996f 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -97,6 +97,7 @@ struct pt_regs {
* ARCH_HAS_PTREGS_AUXILIARY. Failure to do so will result in a build failure.
*/
struct pt_regs_auxiliary {
+ int cpu;
};

struct pt_regs_extended {
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 82cf23975aa1..5df99fe49494 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -768,9 +768,9 @@ static inline void
show_signal_msg(struct pt_regs *regs, unsigned long error_code,
unsigned long address, struct task_struct *tsk)
{
+ struct pt_regs_auxiliary *aux_pt_regs = &to_extended_pt_regs(regs)->aux;
const char *loglvl = task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG;
- /* This is a racy snapshot, but it's better than nothing. */
- int cpu = raw_smp_processor_id();
+ int cpu = aux_pt_regs->cpu;

if (!unhandled_signal(tsk, SIGSEGV))
return;
--
2.35.3
\
 
 \ /
  Last update: 2022-08-05 19:31    [W:0.151 / U:0.320 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site