diff options
Diffstat (limited to 'arch/x86/entry/calling.h')
| -rw-r--r-- | arch/x86/entry/calling.h | 72 |
1 files changed, 59 insertions, 13 deletions
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 3d3389a92c33..7894e5c0eef7 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -3,6 +3,9 @@ #include <asm/unwind_hints.h> #include <asm/cpufeatures.h> #include <asm/page_types.h> +#include <asm/percpu.h> +#include <asm/asm-offsets.h> +#include <asm/processor-flags.h> /* @@ -191,17 +194,21 @@ For 32-bit we have the following conventions - kernel is built with #ifdef CONFIG_PAGE_TABLE_ISOLATION -/* PAGE_TABLE_ISOLATION PGDs are 8k. Flip bit 12 to switch between the two halves: */ -#define PTI_SWITCH_MASK (1<<PAGE_SHIFT) +/* + * PAGE_TABLE_ISOLATION PGDs are 8k. Flip bit 12 to switch between the two + * halves: + */ +#define PTI_SWITCH_PGTABLES_MASK (1<<PAGE_SHIFT) +#define PTI_SWITCH_MASK (PTI_SWITCH_PGTABLES_MASK|(1<<X86_CR3_PTI_SWITCH_BIT)) -.macro ADJUST_KERNEL_CR3 reg:req - /* Clear "PAGE_TABLE_ISOLATION bit", point CR3 at kernel pagetables: */ - andq $(~PTI_SWITCH_MASK), \reg +.macro SET_NOFLUSH_BIT reg:req + bts $X86_CR3_PCID_NOFLUSH_BIT, \reg .endm -.macro ADJUST_USER_CR3 reg:req - /* Move CR3 up a page to the user page tables: */ - orq $(PTI_SWITCH_MASK), \reg +.macro ADJUST_KERNEL_CR3 reg:req + ALTERNATIVE "", "SET_NOFLUSH_BIT \reg", X86_FEATURE_PCID + /* Clear PCID and "PAGE_TABLE_ISOLATION bit", point CR3 at kernel pagetables: */ + andq $(~PTI_SWITCH_MASK), \reg .endm .macro SWITCH_TO_KERNEL_CR3 scratch_reg:req @@ -212,21 +219,58 @@ For 32-bit we have the following conventions - kernel is built with .Lend_\@: .endm -.macro SWITCH_TO_USER_CR3 scratch_reg:req +#define THIS_CPU_user_pcid_flush_mask \ + PER_CPU_VAR(cpu_tlbstate) + TLB_STATE_user_pcid_flush_mask + +.macro SWITCH_TO_USER_CR3_NOSTACK scratch_reg:req scratch_reg2:req ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI mov %cr3, \scratch_reg - ADJUST_USER_CR3 \scratch_reg + + ALTERNATIVE "jmp .Lwrcr3_\@", "", X86_FEATURE_PCID + + /* + * Test if the ASID needs a flush. + */ + movq \scratch_reg, \scratch_reg2 + andq $(0x7FF), \scratch_reg /* mask ASID */ + bt \scratch_reg, THIS_CPU_user_pcid_flush_mask + jnc .Lnoflush_\@ + + /* Flush needed, clear the bit */ + btr \scratch_reg, THIS_CPU_user_pcid_flush_mask + movq \scratch_reg2, \scratch_reg + jmp .Lwrcr3_\@ + +.Lnoflush_\@: + movq \scratch_reg2, \scratch_reg + SET_NOFLUSH_BIT \scratch_reg + +.Lwrcr3_\@: + /* Flip the PGD and ASID to the user version */ + orq $(PTI_SWITCH_MASK), \scratch_reg mov \scratch_reg, %cr3 .Lend_\@: .endm +.macro SWITCH_TO_USER_CR3_STACK scratch_reg:req + pushq %rax + SWITCH_TO_USER_CR3_NOSTACK scratch_reg=\scratch_reg scratch_reg2=%rax + popq %rax +.endm + .macro SAVE_AND_SWITCH_TO_KERNEL_CR3 scratch_reg:req save_reg:req ALTERNATIVE "jmp .Ldone_\@", "", X86_FEATURE_PTI movq %cr3, \scratch_reg movq \scratch_reg, \save_reg /* - * Is the switch bit zero? This means the address is - * up in real PAGE_TABLE_ISOLATION patches in a moment. + * Is the "switch mask" all zero? That means that both of + * these are zero: + * + * 1. The user/kernel PCID bit, and + * 2. The user/kernel "bit" that points CR3 to the + * bottom half of the 8k PGD + * + * That indicates a kernel CR3 value, not a user CR3. */ testq $(PTI_SWITCH_MASK), \scratch_reg jz .Ldone_\@ @@ -251,7 +295,9 @@ For 32-bit we have the following conventions - kernel is built with .macro SWITCH_TO_KERNEL_CR3 scratch_reg:req .endm -.macro SWITCH_TO_USER_CR3 scratch_reg:req +.macro SWITCH_TO_USER_CR3_NOSTACK scratch_reg:req scratch_reg2:req +.endm +.macro SWITCH_TO_USER_CR3_STACK scratch_reg:req .endm .macro SAVE_AND_SWITCH_TO_KERNEL_CR3 scratch_reg:req save_reg:req .endm |