Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f774b7d1 authored by Marc Zyngier's avatar Marc Zyngier Committed by Catalin Marinas
Browse files

arm64: fixmap: fix missing sub-page offset for earlyprintk 



Commit d57c33c5 (add generic fixmap.h) added (among other
similar things) set_fixmap_io to deal with early ioremap of devices.

More recently, commit bf4b558e (arm64: add early_ioremap support)
converted the arm64 earlyprintk to use set_fixmap_io. A side effect of
this conversion is that my virtual machines have stopped booting when
I pass "earlyprintk=uart8250-8bit,0x3f8" to the guest kernel.

Turns out that the new earlyprintk code doesn't care at all about
sub-page offsets, and just assumes that the earlyprintk device will
be page-aligned. Obviously, that doesn't play well with the above example.

Further investigation shows that set_fixmap_io uses __set_fixmap instead
of __set_fixmap_offset. A fix is to introduce a set_fixmap_offset_io that
uses the latter, and to remove the superflous call to fix_to_virt
(which only returns the value that set_fixmap_io has already given us).

With this applied, my VMs are back in business. Tested on a Cortex-A57
platform with kvmtool as platform emulation.

Cc: Will Deacon <will.deacon@arm.com>
Acked-by: default avatarMark Salter <msalter@redhat.com>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent da6e4cb6

arch/arm64/kernel/early_printk.c

+2 −4
Original line number Diff line number Diff line
@@ -143,10 +143,8 @@ static int __init setup_early_printk(char *buf) 
	}

	/* no options parsing yet */



	if (paddr) {

		set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr);

		early_base = (void __iomem *)fix_to_virt(FIX_EARLYCON_MEM_BASE);

	}

	if (paddr)

		early_base = (void __iomem *)set_fixmap_offset_io(FIX_EARLYCON_MEM_BASE, paddr);



	printch = match->printch;

	early_console = &early_console_dev;

include/asm-generic/fixmap.h

+3 −0
Original line number Diff line number Diff line
@@ -93,5 +93,8 @@ static inline unsigned long virt_to_fix(const unsigned long vaddr) 
#define set_fixmap_io(idx, phys) \

	__set_fixmap(idx, phys, FIXMAP_PAGE_IO)



#define set_fixmap_offset_io(idx, phys) \

	__set_fixmap_offset(idx, phys, FIXMAP_PAGE_IO)



#endif /* __ASSEMBLY__ */

#endif /* __ASM_GENERIC_FIXMAP_H */