| Message ID | 20201208011034.3015079-1-dann.frazier@canonical.com |
|---|---|
| State | New |
| Headers | show |
| Series | [4.4] arm64: assembler: make adr_l work in modules under KASLR | expand |
On Mon, Dec 07, 2020 at 06:10:34PM -0700, dann frazier wrote: > From: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > commit 41c066f2c4d436c535616fe182331766c57838f0 upstream > > When CONFIG_RANDOMIZE_MODULE_REGION_FULL=y, the offset between loaded > modules and the core kernel may exceed 4 GB, putting symbols exported > by the core kernel out of the reach of the ordinary adrp/add instruction > pairs used to generate relative symbol references. So make the adr_l > macro emit a movz/movk sequence instead when executing in module context. > > While at it, remove the pointless special case for the stack pointer. > > Acked-by: Mark Rutland <mark.rutland@arm.com> > Acked-by: Will Deacon <will.deacon@arm.com> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > [ dannf: backported to v4.4 by replacing the 3-arg adr_l macro in head.S > with it's output, as this commit drops the 3-arg variant ] > Fixes: c042dd600f4e ("crypto: arm64/sha - avoid non-standard inline asm tricks") > Signed-off-by: dann frazier <dann.frazier@canonical.com> > --- > arch/arm64/include/asm/assembler.h | 36 +++++++++++++++++++++++++++--------- > arch/arm64/kernel/head.S | 3 ++- > 2 files changed, 29 insertions(+), 10 deletions(-) Now queued up, thanks! greg k-h
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index f68abb1..7c28791 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -148,22 +148,25 @@ lr .req x30 // link register /* * Pseudo-ops for PC-relative adr/ldr/str <reg>, <symbol> where - * <symbol> is within the range +/- 4 GB of the PC. + * <symbol> is within the range +/- 4 GB of the PC when running + * in core kernel context. In module context, a movz/movk sequence + * is used, since modules may be loaded far away from the kernel + * when KASLR is in effect. */ /* * @dst: destination register (64 bit wide) * @sym: name of the symbol - * @tmp: optional scratch register to be used if <dst> == sp, which - * is not allowed in an adrp instruction */ - .macro adr_l, dst, sym, tmp= - .ifb \tmp + .macro adr_l, dst, sym +#ifndef MODULE adrp \dst, \sym add \dst, \dst, :lo12:\sym - .else - adrp \tmp, \sym - add \dst, \tmp, :lo12:\sym - .endif +#else + movz \dst, #:abs_g3:\sym + movk \dst, #:abs_g2_nc:\sym + movk \dst, #:abs_g1_nc:\sym + movk \dst, #:abs_g0_nc:\sym +#endif .endm /* @@ -174,6 +177,7 @@ lr .req x30 // link register * the address */ .macro ldr_l, dst, sym, tmp= +#ifndef MODULE .ifb \tmp adrp \dst, \sym ldr \dst, [\dst, :lo12:\sym] @@ -181,6 +185,15 @@ lr .req x30 // link register adrp \tmp, \sym ldr \dst, [\tmp, :lo12:\sym] .endif +#else + .ifb \tmp + adr_l \dst, \sym + ldr \dst, [\dst] + .else + adr_l \tmp, \sym + ldr \dst, [\tmp] + .endif +#endif .endm /* @@ -190,8 +203,13 @@ lr .req x30 // link register * while <src> needs to be preserved. */ .macro str_l, src, sym, tmp +#ifndef MODULE adrp \tmp, \sym str \src, [\tmp, :lo12:\sym] +#else + adr_l \tmp, \sym + str \src, [\tmp] +#endif .endm /* diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 6299a8a..504bcc3 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -424,7 +424,8 @@ __mmap_switched: str xzr, [x6], #8 // Clear BSS b 1b 2: - adr_l sp, initial_sp, x4 + adrp x4, initial_sp + add sp, x4, :lo12:initial_sp str_l x21, __fdt_pointer, x5 // Save FDT pointer str_l x24, memstart_addr, x6 // Save PHYS_OFFSET mov x29, #0