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Subject[tip: x86/mm] x86/mm/kmmio: Use this_cpu_ptr() instead get_cpu_var() for kmmio_ctx
The following commit has been merged into the x86/mm branch of tip:

Commit-ID: 6a9feaa8774f3b8210dfe40626a75ca047e4ecae
Gitweb: https://git.kernel.org/tip/6a9feaa8774f3b8210dfe40626a75ca047e4ecae
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Wed, 05 Feb 2020 15:34:26 +01:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Thu, 12 Mar 2020 16:41:40 +01:00

x86/mm/kmmio: Use this_cpu_ptr() instead get_cpu_var() for kmmio_ctx

Both call sites that access kmmio_ctx, access kmmio_ctx with interrupts
disabled. There is no need to use get_cpu_var() which additionally
disables preemption.

Use this_cpu_ptr() to access the kmmio_ctx variable of the current CPU.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200205143426.2592512-1-bigeasy@linutronix.de
---
arch/x86/mm/kmmio.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index 49d7814..9994353 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -260,7 +260,7 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr)
goto no_kmmio;
}

- ctx = &get_cpu_var(kmmio_ctx);
+ ctx = this_cpu_ptr(&kmmio_ctx);
if (ctx->active) {
if (page_base == ctx->addr) {
/*
@@ -285,7 +285,7 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr)
pr_emerg("previous hit was at 0x%08lx.\n", ctx->addr);
disarm_kmmio_fault_page(faultpage);
}
- goto no_kmmio_ctx;
+ goto no_kmmio;
}
ctx->active++;

@@ -314,11 +314,8 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr)
* the user should drop to single cpu before tracing.
*/

- put_cpu_var(kmmio_ctx);
return 1; /* fault handled */

-no_kmmio_ctx:
- put_cpu_var(kmmio_ctx);
no_kmmio:
rcu_read_unlock();
preempt_enable_no_resched();
@@ -333,7 +330,7 @@ no_kmmio:
static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
{
int ret = 0;
- struct kmmio_context *ctx = &get_cpu_var(kmmio_ctx);
+ struct kmmio_context *ctx = this_cpu_ptr(&kmmio_ctx);

if (!ctx->active) {
/*
@@ -371,7 +368,6 @@ static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
if (!(regs->flags & X86_EFLAGS_TF))
ret = 1;
out:
- put_cpu_var(kmmio_ctx);
return ret;
}

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