The following commit has been merged into the x86/asm branch of tip:
Commit-ID: bc90aefa99f74452d549d503a3f1cbf3adc9c6bb
Gitweb: https://git.kernel.org/tip/bc90aefa99f74452d549d503a3f1cbf3adc9c6bb
Author: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
AuthorDate: Tue, 19 Dec 2023 16:12:00 +01:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 20 Dec 2023 10:57:51 +01:00
x86/asm: Add DB flag to 32-bit percpu GDT entry
The D/B size flag for the 32-bit percpu GDT entry was not set.
The Intel manual (vol 3, section 3.4.5) only specifies the meaning of
this flag for three cases:
1) code segments used for %cs -- doesn't apply here
2) stack segments used for %ss -- doesn't apply
3) expand-down data segments -- but we don't have the expand-down flag
set, so it also doesn't apply here
The flag likely doesn't do anything here, although the manual does also
say: "This flag should always be set to 1 for 32-bit code and data
segments [...]" so we should probably do it anyway.
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20231219151200.2878271-6-vegard.nossum@xxxxxxxxxx
---
arch/x86/kernel/setup_percpu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index f2583de..b30d6e1 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -106,7 +106,7 @@ void __init pcpu_populate_pte(unsigned long addr)
static inline void setup_percpu_segment(int cpu)
{
#ifdef CONFIG_X86_32
- struct desc_struct d = GDT_ENTRY_INIT(DESC_DATA32 & ~_DESC_DB,
+ struct desc_struct d = GDT_ENTRY_INIT(DESC_DATA32,
per_cpu_offset(cpu), 0xFFFFF);
write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PERCPU, &d, DESCTYPE_S);
|