diff mbox series

[3/6] powerpc/85xx: Fix virt_to_phys() off-by-one in smp_85xx_start_cpu()

Message ID 20220406145802.538416-3-mpe@ellerman.id.au (mailing list archive)
State Accepted
Headers show
Series [1/6] powerpc: Fix virt_addr_valid() for 64-bit Book3E & 32-bit | expand

Commit Message

Michael Ellerman April 6, 2022, 2:57 p.m. UTC
In smp_85xx_start_cpu() we are passed an address but we're unsure if
it's a real or virtual address, so there's a check to determine that.

The check has an off-by-one in that it tests if the address is greater
than high_memory, but high_memory is the first address of high memory,
so the check should be greater-or-equal.

It seems this has never been a problem in practice, but it also triggers
the DEBUG_VIRTUAL checks in __pa() which we would like to avoid. We can
fix both issues by converting high_memory - 1 to a physical address and
testing against that.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/platforms/85xx/smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Michael Ellerman May 15, 2022, 10:21 a.m. UTC | #1
On Thu, 7 Apr 2022 00:57:59 +1000, Michael Ellerman wrote:
> In smp_85xx_start_cpu() we are passed an address but we're unsure if
> it's a real or virtual address, so there's a check to determine that.
> 
> [...]

Applied to powerpc/next.

[3/6] powerpc/85xx: Fix virt_to_phys() off-by-one in smp_85xx_start_cpu()
      https://git.kernel.org/powerpc/c/0d897255e79e26f471d10bbf72db9eee6f9cb723

cheers
diff mbox series

Patch

diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c
index a1c6a7827c8f..9c43cf32f4c9 100644
--- a/arch/powerpc/platforms/85xx/smp.c
+++ b/arch/powerpc/platforms/85xx/smp.c
@@ -208,7 +208,7 @@  static int smp_85xx_start_cpu(int cpu)
 	 * The bootpage and highmem can be accessed via ioremap(), but
 	 * we need to directly access the spinloop if its in lowmem.
 	 */
-	ioremappable = *cpu_rel_addr > virt_to_phys(high_memory);
+	ioremappable = *cpu_rel_addr > virt_to_phys(high_memory - 1);
 
 	/* Map the spin table */
 	if (ioremappable)