| Message ID | 1427107977-18591-1-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 23 March 2015 at 12:40, Will Deacon <will.deacon@arm.com> wrote: > On Mon, Mar 23, 2015 at 10:52:57AM +0000, Ard Biesheuvel wrote: >> Commit 06f75a1f6200 ("ARM, arm64: kvm: get rid of the bounce >> page") uses ld's builtin function LOG2CEIL() to align the >> KVM init code to a log2 upper bound of its size. However, >> this function turns out to be a fairly recent addition to >> binutils, which breaks the build for older toolchains. >> >> So instead, implement a replacement LOG2_ROUNDUP() using >> the C preprocessor. >> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> --- >> >> Linker map output after applying this patch: >> >> 0xc09a2590 __idmap_text_end = . >> [...] >> *fill* 0xc09a2590 0x70 >> 0xc09a2600 __hyp_idmap_text_start = . >> *(.hyp.idmap.text) >> .hyp.idmap.text >> 0xc09a2600 0x100 arch/arm/kvm/built-in.o >> 0xc09a2600 __kvm_hyp_init >> 0xc09a26ec __kvm_hyp_init_end >> 0xc09a2700 __hyp_idmap_text_end = . >> >> which confirms that the alignemnt is correct. The size of the region >> is 0xec bytes, and 0x70 bytes of padding are emitted to align it at >> a 0x100 byte boundary >> >> arch/arm/kernel/vmlinux.lds.S | 24 ++++++++++++++++++++++-- >> 1 file changed, 22 insertions(+), 2 deletions(-) > > Thanks Ard. I pushed this on top of kvm-bounce-page and re-generated > for-next/core. > OK. I double checked the ARM build with your version, and it looks the same. I also built and booted it on my Seattle using 4k/3 levels, and everything works as expected. Cheers, Ard.
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index ba65f1217310..2d760df0d57d 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -11,7 +11,27 @@ #ifdef CONFIG_ARM_KERNMEM_PERMS #include <asm/pgtable.h> #endif - + +/* + * Poor man's version of LOG2CEIL(), which is + * not available in binutils before v2.24. + */ +#define LOG2_ROUNDUP(size) ( \ + __LOG2_ROUNDUP(size, 2) \ + __LOG2_ROUNDUP(size, 3) \ + __LOG2_ROUNDUP(size, 4) \ + __LOG2_ROUNDUP(size, 5) \ + __LOG2_ROUNDUP(size, 6) \ + __LOG2_ROUNDUP(size, 7) \ + __LOG2_ROUNDUP(size, 8) \ + __LOG2_ROUNDUP(size, 9) \ + __LOG2_ROUNDUP(size, 10) \ + __LOG2_ROUNDUP(size, 11) \ + 12) + +#define __LOG2_ROUNDUP(size, order) \ + (size) <= (1 << order) ? order : + #define PROC_INFO \ . = ALIGN(4); \ VMLINUX_SYMBOL(__proc_info_begin) = .; \ @@ -23,7 +43,7 @@ VMLINUX_SYMBOL(__idmap_text_start) = .; \ *(.idmap.text) \ VMLINUX_SYMBOL(__idmap_text_end) = .; \ - . = ALIGN(1 << LOG2CEIL(__hyp_idmap_size)); \ + . = ALIGN(1 << LOG2_ROUNDUP(__hyp_idmap_size)); \ VMLINUX_SYMBOL(__hyp_idmap_text_start) = .; \ *(.hyp.idmap.text) \ VMLINUX_SYMBOL(__hyp_idmap_text_end) = .;
Commit 06f75a1f6200 ("ARM, arm64: kvm: get rid of the bounce page") uses ld's builtin function LOG2CEIL() to align the KVM init code to a log2 upper bound of its size. However, this function turns out to be a fairly recent addition to binutils, which breaks the build for older toolchains. So instead, implement a replacement LOG2_ROUNDUP() using the C preprocessor. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- Linker map output after applying this patch: 0xc09a2590 __idmap_text_end = . [...] *fill* 0xc09a2590 0x70 0xc09a2600 __hyp_idmap_text_start = . *(.hyp.idmap.text) .hyp.idmap.text 0xc09a2600 0x100 arch/arm/kvm/built-in.o 0xc09a2600 __kvm_hyp_init 0xc09a26ec __kvm_hyp_init_end 0xc09a2700 __hyp_idmap_text_end = . which confirms that the alignemnt is correct. The size of the region is 0xec bytes, and 0x70 bytes of padding are emitted to align it at a 0x100 byte boundary arch/arm/kernel/vmlinux.lds.S | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-)