Messages in this thread | | | Subject | Re: [PATCH v3 2/2] riscv: Enable per-task stack canaries | From | cooper <> | Date | Wed, 15 Jul 2020 11:14:57 +0800 |
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On 2020/7/15 上午5:37, Palmer Dabbelt wrote: > On Fri, 10 Jul 2020 09:19:58 PDT (-0700), guoren@kernel.org wrote: >> From: Guo Ren <guoren@linux.alibaba.com> >> >> This enables the use of per-task stack canary values if GCC has >> support for emitting the stack canary reference relative to the >> value of tp, which holds the task struct pointer in the riscv >> kernel. >> >> After compare arm64 and x86 implementations, seems arm64's is more >> flexible and readable. The key point is how gcc get the offset of >> stack_canary from gs/el0_sp. >> >> x86: Use a fix offset from gs, not flexible. >> >> struct fixed_percpu_data { >> /* >> * GCC hardcodes the stack canary as %gs:40. Since the >> * irq_stack is the object at %gs:0, we reserve the bottom >> * 48 bytes of the irq stack for the canary. >> */ >> char gs_base[40]; // :( >> unsigned long stack_canary; >> }; >> >> arm64: Use -mstack-protector-guard-offset & guard-reg >> gcc options: >> -mstack-protector-guard=sysreg >> -mstack-protector-guard-reg=sp_el0 >> -mstack-protector-guard-offset=xxx >> >> riscv: Use -mstack-protector-guard-offset & guard-reg >> gcc options: >> -mstack-protector-guard=tls >> -mstack-protector-guard-reg=tp >> -mstack-protector-guard-offset=xxx >> >> Here is riscv gcc's work [1]. >> >> [1] https://gcc.gnu.org/pipermail/gcc-patches/2020-July/549583.html >> >> In the end, these codes are inserted by gcc before return: >> >> * 0xffffffe00020b396 <+120>: ld a5,1008(tp) # 0x3f0 >> * 0xffffffe00020b39a <+124>: xor a5,a5,a4 >> * 0xffffffe00020b39c <+126>: mv a0,s5 >> * 0xffffffe00020b39e <+128>: bnez a5,0xffffffe00020b61c >> <_do_fork+766> >> 0xffffffe00020b3a2 <+132>: ld ra,136(sp) >> 0xffffffe00020b3a4 <+134>: ld s0,128(sp) >> 0xffffffe00020b3a6 <+136>: ld s1,120(sp) >> 0xffffffe00020b3a8 <+138>: ld s2,112(sp) >> 0xffffffe00020b3aa <+140>: ld s3,104(sp) >> 0xffffffe00020b3ac <+142>: ld s4,96(sp) >> 0xffffffe00020b3ae <+144>: ld s5,88(sp) >> 0xffffffe00020b3b0 <+146>: ld s6,80(sp) >> 0xffffffe00020b3b2 <+148>: ld s7,72(sp) >> 0xffffffe00020b3b4 <+150>: addi sp,sp,144 >> 0xffffffe00020b3b6 <+152>: ret >> ... >> * 0xffffffe00020b61c <+766>: auipc ra,0x7f8 >> * 0xffffffe00020b620 <+770>: jalr -1764(ra) # >> 0xffffffe000a02f38 <__stack_chk_fail> >> >> Signed-off-by: Guo Ren <guoren@linux.alibaba.com> >> Signed-off-by: cooper <cooper.qu@linux.alibaba.com> > > IIRC we're required to use full names here. I'm assuming that's meant > to be > "Signed-off-by: Cooper Qu ...", and I know it's a bit procedural but I > can't > make that change. > > Otherwise these two look good, the first one is on for-next. I can > boot with a > defconfig ammended with CONFIG_STACKPROTECTOR=y, > Thanks! > Hi Palmer,
That's ok to change it to full names as follows.
Signed-off-by: Cooper Qu <cooper.qu@linux.alibaba.com>
Best Regards,
Cooper
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