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2b951b0efb
Commitc76c6c4ecb("ARM: 9294/2: vfp: Fix broken softirq handling with instrumentation enabled") updated the VFP exception entry logic to go via a C function, so that we get the compiler's version of local_bh_disable(), which may be instrumented, and isn't generally callable from assembler. However, this assumes that passing an alternative 'success' return address works in C as it does in asm, and this is only the case if the C calls in question are tail calls, as otherwise, the stack will need some unwinding as well. I have already sent patches to the list that replace most of the asm logic with C code, and so it is preferable to have a minimal fix that addresses the issue and can be backported along with the commit that it fixes to v6.3 from v6.4. Hopefully, we can land the C conversion for v6.5. So instead of passing the 'success' return address as a function argument, pass the stack address from where to pop it so that both LR and SP have the expected value. Fixes:c76c6c4ecb("ARM: 9294/2: vfp: Fix broken softirq handling with ...") Reported-by: syzbot+d4b00edc2d0c910d4bf4@syzkaller.appspotmail.com Tested-by: syzbot+d4b00edc2d0c910d4bf4@syzkaller.appspotmail.com Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Tested-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
32 lines
757 B
ArmAsm
32 lines
757 B
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* linux/arch/arm/vfp/entry.S
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*
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* Copyright (C) 2004 ARM Limited.
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* Written by Deep Blue Solutions Limited.
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*/
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#include <linux/init.h>
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#include <linux/linkage.h>
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#include <asm/thread_info.h>
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#include <asm/vfpmacros.h>
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#include <asm/assembler.h>
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#include <asm/asm-offsets.h>
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@ VFP entry point.
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@
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@ r0 = instruction opcode (32-bit ARM or two 16-bit Thumb)
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@ r2 = PC value to resume execution after successful emulation
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@ r9 = normal "successful" return address
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@ r10 = this threads thread_info structure
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@ lr = unrecognised instruction return address
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@ IRQs enabled.
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@
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ENTRY(do_vfp)
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mov r1, r10
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str lr, [sp, #-8]!
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add r3, sp, #4
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str r9, [r3]
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bl vfp_entry
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ldr pc, [sp], #8
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ENDPROC(do_vfp)
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