| Message ID | 1470716340-24474-3-git-send-email-konrad.wilk@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Konrad, On 09/08/2016 06:18, Konrad Rzeszutek Wilk wrote: > We copied from Linux code (v4.7) the code that generates > the unconditional branch instructions. This is mostly > from Linux commit c0cafbae20d2878883ec3c06d6ea30ff38a6bf92 > "arm64: introduce aarch64_insn_gen_branch_reg()" > > However the branch-link instructions was omitted, only > the branch instruction is generated. I would prefer to have the function fully copied (i.e with the branch-link instructions). This will make easier to re-sync the code later on. > > This lays the groundwork for Livepatch to generate the > trampoline to jump to the new replacement function. > > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > -- > Cc: Ross Lagerwall <ross.lagerwall@citrix.com> > Cc: Stefano Stabellini <sstabellini@kernel.org> > Cc: Julien Grall <julien.grall@arm.com> > --- > xen/arch/arm/arm64/insn.c | 41 ++++++++++++++++++++++++++++++++++++++++ > xen/include/asm-arm/arm64/insn.h | 2 ++ > 2 files changed, 43 insertions(+) > > diff --git a/xen/arch/arm/arm64/insn.c b/xen/arch/arm/arm64/insn.c > index 12b4d96..15dd7bc 100644 > --- a/xen/arch/arm/arm64/insn.c > +++ b/xen/arch/arm/arm64/insn.c > @@ -209,6 +209,47 @@ u32 aarch64_set_branch_offset(u32 insn, s32 offset) > BUG(); > } > > +static inline long branch_imm_common(unsigned long pc, unsigned long addr, > + long range) > +{ > + long offset; > + > + if ((pc & 0x3) || (addr & 0x3)) { > + pr_err("%s: A64 instructions must be word aligned\n", __func__); > + return range; > + } > + > + offset = ((long)addr - (long)pc); > + > + if (offset < -range || offset >= range) { > + pr_err("%s: offset out of range\n", __func__); > + return range; > + } > + > + return offset; > +} > + > +u32 __kprobes aarch64_insn_gen_branch_imm(unsigned long pc, unsigned long addr) > +{ > + u32 insn; > + long offset; > + > + /* > + * B/BL support [-128M, 128M) offset > + * ARM64 virtual address arrangement guarantees all kernel and module > + * texts are within +/-128M. > + */ > + offset = branch_imm_common(pc, addr, SZ_128M); > + if (offset >= SZ_128M) > + return AARCH64_BREAK_FAULT; > + > + insn = aarch64_insn_get_b_value(); > + > + return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_26, insn, > + offset >> 2); > +} I would prefer to have the functions added at the same place as in Linux for similar reason as stated previously. > + > + I think you can drop one empty line here. > /* > * Local variables: > * mode: C > diff --git a/xen/include/asm-arm/arm64/insn.h b/xen/include/asm-arm/arm64/insn.h > index 6ce37be..378ba11 100644 > --- a/xen/include/asm-arm/arm64/insn.h > +++ b/xen/include/asm-arm/arm64/insn.h > @@ -61,6 +61,8 @@ u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type, > s32 aarch64_get_branch_offset(u32 insn); > u32 aarch64_set_branch_offset(u32 insn, s32 offset); > > +u32 aarch64_insn_gen_branch_imm(unsigned long pc, unsigned long addr); > + > /* Wrapper for common code */ > static inline bool insn_is_branch_imm(u32 insn) > { > Regards,
diff --git a/xen/arch/arm/arm64/insn.c b/xen/arch/arm/arm64/insn.c index 12b4d96..15dd7bc 100644 --- a/xen/arch/arm/arm64/insn.c +++ b/xen/arch/arm/arm64/insn.c @@ -209,6 +209,47 @@ u32 aarch64_set_branch_offset(u32 insn, s32 offset) BUG(); } +static inline long branch_imm_common(unsigned long pc, unsigned long addr, + long range) +{ + long offset; + + if ((pc & 0x3) || (addr & 0x3)) { + pr_err("%s: A64 instructions must be word aligned\n", __func__); + return range; + } + + offset = ((long)addr - (long)pc); + + if (offset < -range || offset >= range) { + pr_err("%s: offset out of range\n", __func__); + return range; + } + + return offset; +} + +u32 __kprobes aarch64_insn_gen_branch_imm(unsigned long pc, unsigned long addr) +{ + u32 insn; + long offset; + + /* + * B/BL support [-128M, 128M) offset + * ARM64 virtual address arrangement guarantees all kernel and module + * texts are within +/-128M. + */ + offset = branch_imm_common(pc, addr, SZ_128M); + if (offset >= SZ_128M) + return AARCH64_BREAK_FAULT; + + insn = aarch64_insn_get_b_value(); + + return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_26, insn, + offset >> 2); +} + + /* * Local variables: * mode: C diff --git a/xen/include/asm-arm/arm64/insn.h b/xen/include/asm-arm/arm64/insn.h index 6ce37be..378ba11 100644 --- a/xen/include/asm-arm/arm64/insn.h +++ b/xen/include/asm-arm/arm64/insn.h @@ -61,6 +61,8 @@ u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type, s32 aarch64_get_branch_offset(u32 insn); u32 aarch64_set_branch_offset(u32 insn, s32 offset); +u32 aarch64_insn_gen_branch_imm(unsigned long pc, unsigned long addr); + /* Wrapper for common code */ static inline bool insn_is_branch_imm(u32 insn) {
We copied from Linux code (v4.7) the code that generates the unconditional branch instructions. This is mostly from Linux commit c0cafbae20d2878883ec3c06d6ea30ff38a6bf92 "arm64: introduce aarch64_insn_gen_branch_reg()" However the branch-link instructions was omitted, only the branch instruction is generated. This lays the groundwork for Livepatch to generate the trampoline to jump to the new replacement function. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> -- Cc: Ross Lagerwall <ross.lagerwall@citrix.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Julien Grall <julien.grall@arm.com> --- xen/arch/arm/arm64/insn.c | 41 ++++++++++++++++++++++++++++++++++++++++ xen/include/asm-arm/arm64/insn.h | 2 ++ 2 files changed, 43 insertions(+)