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| author | Andy Lutomirski <luto@kernel.org> | 2018-09-04 00:59:43 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-09-08 11:20:11 +0200 |
| commit | 98f05b5138f0a9b56022295cc1387e635b25635d (patch) | |
| tree | e116b364861f976467534b78bbce1771abdebf54 /arch/x86/xen/xen-asm_64.S | |
| parent | x86/entry/64: Document idtentry (diff) | |
| download | linux-98f05b5138f0a9b56022295cc1387e635b25635d.tar.xz linux-98f05b5138f0a9b56022295cc1387e635b25635d.zip | |
x86/entry/64: Use the TSS sp2 slot for SYSCALL/SYSRET scratch space
In the non-trampoline SYSCALL64 path, a percpu variable is used to
temporarily store the user RSP value.
Instead of a separate variable, use the otherwise unused sp2 slot in the
TSS. This will improve cache locality, as the sp1 slot is already used in
the same code to find the kernel stack. It will also simplify a future
change to make the non-trampoline path work in PTI mode.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/08e769a0023dbad4bac6f34f3631dbaf8ad59f4f.1536015544.git.luto@kernel.org
Diffstat (limited to 'arch/x86/xen/xen-asm_64.S')
| -rw-r--r-- | arch/x86/xen/xen-asm_64.S | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index 417b339e5c8e..bb1c2da0381d 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -91,13 +91,15 @@ ENTRY(xen_iret) ENTRY(xen_sysret64) /* * We're already on the usermode stack at this point, but - * still with the kernel gs, so we can easily switch back + * still with the kernel gs, so we can easily switch back. + * + * tss.sp2 is scratch space. */ - movq %rsp, PER_CPU_VAR(rsp_scratch) + movq %rsp, PER_CPU_VAR(cpu_tss_rw + TSS_sp2) movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp pushq $__USER_DS - pushq PER_CPU_VAR(rsp_scratch) + pushq PER_CPU_VAR(cpu_tss_rw + TSS_sp2) pushq %r11 pushq $__USER_CS pushq %rcx |