linux-kernel - [PATCH 4.19 106/205] ARM: 8809/1: proc-v7: fix Thumb annotation of cpu_v7_hvc_switch

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Date:   Mon, 19 Nov 2018 17:26:53 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dave Martin <Dave.Martin@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Russell King <rmk+kernel@...linux.org.uk>
Subject: [PATCH 4.19 106/205] ARM: 8809/1: proc-v7: fix Thumb annotation of cpu_v7_hvc_switch_mm

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ard Biesheuvel <ard.biesheuvel@...aro.org>

commit 6282e916f774e37845c65d1eae9f8c649004f033 upstream.

Due to what appears to be a copy/paste error, the opening ENTRY()
of cpu_v7_hvc_switch_mm() lacks a matching ENDPROC(), and instead,
the one for cpu_v7_smc_switch_mm() is duplicated.

Given that it is ENDPROC() that emits the Thumb annotation, the
cpu_v7_hvc_switch_mm() routine will be called in ARM mode on a
Thumb2 kernel, resulting in the following splat:

  Internal error: Oops - undefined instruction: 0 [#1] SMP THUMB2
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.18.0-rc1-00030-g4d28ad89189d-dirty #488
  Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
  PC is at cpu_v7_hvc_switch_mm+0x12/0x18
  LR is at flush_old_exec+0x31b/0x570
  pc : [<c0316efe>]    lr : [<c04117c7>]    psr: 00000013
  sp : ee899e50  ip : 00000000  fp : 00000001
  r10: eda28f34  r9 : eda31800  r8 : c12470e0
  r7 : eda1fc00  r6 : eda53000  r5 : 00000000  r4 : ee88c000
  r3 : c0316eec  r2 : 00000001  r1 : eda53000  r0 : 6da6c000
  Flags: nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none

Note the 'ISA ARM' in the last line.

Fix this by using the correct name in ENDPROC().

Cc: <stable@...r.kernel.org>
Fixes: 10115105cb3a ("ARM: spectre-v2: add firmware based hardening")
Reviewed-by: Dave Martin <Dave.Martin@....com>
Acked-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm/mm/proc-v7.S |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -112,7 +112,7 @@ ENTRY(cpu_v7_hvc_switch_mm)
 	hvc	#0
 	ldmfd	sp!, {r0 - r3}
 	b	cpu_v7_switch_mm
-ENDPROC(cpu_v7_smc_switch_mm)
+ENDPROC(cpu_v7_hvc_switch_mm)
 #endif
 ENTRY(cpu_v7_iciallu_switch_mm)
 	mov	r3, #0