From: Julien Grall <julien.grall@arm.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
konrad@kernel.org, xen-devel@lists.xenproject.org,
ross.lagerwall@citrix.com, sstabellini@kernel.org
Subject: Re: [PATCH v5 14/16] livepatch: Initial ARM32 support.
Date: Tue, 27 Sep 2016 09:39:06 -0700 [thread overview]
Message-ID: <829630b3-e7ca-b62d-d3a1-7742d64fcc05@arm.com> (raw)
In-Reply-To: <1474479154-20991-15-git-send-email-konrad.wilk@oracle.com>
Hi Konrad,
On 21/09/2016 10:32, Konrad Rzeszutek Wilk wrote:
> The patch piggybacks on: livepatch: Initial ARM64 support, which
> brings up all of the necessary livepatch infrastructure pieces in.
>
> This patch adds three major pieces:
>
> 1) ELF relocations. ARM32 uses SHT_REL instead of SHT_RELA which
> means the adddendum had to be extracted from within the
> instruction. Which required parsing BL/BLX, B/BL<cond>,
> MOVT, and MOVW instructions.
>
> The code was written from scratch using the ARM ELF manual
> (and the ARM Architecture Reference Manual)
>
> 2) Inserting an trampoline. We use the B (branch to address)
> which uses an offset that is based on the PC value: PC + imm32.
> Because we insert the branch at the start of the old function
> we have to account for the instruction already being fetched
> and subtract -8 from the delta (new_addr - old_addr). See
> ARM DDI 0406C.c, see A2.3 (pg 45) and A8.8.18 pg (pg 334,335)
>
> 3) Allows the test-cases to be built under ARM 32.
> The "livepatch: tests: Make them compile under ARM64"
> put in the right infrastructure for it and we piggyback on it.
>
> Acked-by: Julien Grall <julien.grall@arm.com>
> Acked-by: Jan Beulich <jbeulich@suse.com> [for non-ARM parts]
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
> Cc: Julien Grall <julien.grall@arm.com>
> Cc: Stefano Stabellini <sstabellini@kernel.org>
>
> v2: First submission.
> v3: Use LIVEPATCH_ARCH_RANGE instead of NEGATIVE_32MB macro
> -Use PATCH_INSN_SIZE instead of the value 4.
> -Ditch the old_ptr local variable.
> -Use 8 for evaluating the branch instead of 4. Based on ARM docs.
> -NOP patch up to sizeof(opaque) % PATCH_INSN_SIZE (so 7 instructions).
> -Don't mask 0x00FFFFF_E_ after shifting, instead mask by 0x00FFFFF_F_.
> The reason is that offset is constructed by shifting by two the insn
> (except the first two bytes) by left which meant we would have cleared
> offset[2]! - and jumped to a location that was -4 bytes off.
> -Update commit description to have -8 instead of -4 delta and also
> include reference to spec.
> v4: Added Jan's Ack.
> s/PATCH_INSN_SIZE/ARCH_PATCH_INSN_SIZE/
> s/arch_livepatch_insn_len/livepatch_insn_len/
> s/LIVEPATCH_ARCH_RANGE/ARCH_LIVEPATCH_RANGE/
> v5: Added Julien's Ack.
IHMO my ack should not have been retained given that ...
> - Rebased on "livepatch: Drop _jmp from arch_livepatch_[apply,revert]_jmp"
> - Added explanation for the usage of data cache and why we need to sync it.
... you also replace the clean_and_invalidate to the old_ptr by
clean_and_invalidate to the new_ptr.
> diff --git a/xen/arch/arm/arm32/livepatch.c b/xen/arch/arm/arm32/livepatch.c
> index 80f9646..3f47326 100644
> --- a/xen/arch/arm/arm32/livepatch.c
> +++ b/xen/arch/arm/arm32/livepatch.c
> @@ -3,28 +3,303 @@
> */
>
> #include <xen/errno.h>
> +#include <xen/kernel.h>
> #include <xen/lib.h>
> #include <xen/livepatch_elf.h>
> #include <xen/livepatch.h>
>
> +#include <asm/page.h>
> +#include <asm/livepatch.h>
> +
> void arch_livepatch_apply(struct livepatch_func *func)
> {
[...]
> + /*
> + * When we upload the payload, it will go through the data cache
> + * (the region is cacheable). Until the data cache is cleaned, the data
> + * may not reach the memory. And in the case the data and instruction cache
> + * are separated, we may read invalid instruction from the memory because
> + * the data cache have not yet synced with the memory. Hence sync it.
> + */
> + if ( func->new_addr )
> + clean_and_invalidate_dcache_va_range(func->new_addr, func->new_size);
The clean_and_invalidate on the new_ptr needs to be add back here and ...
> }
>
> void arch_livepatch_revert(const struct livepatch_func *func)
> {
> + uint32_t *new_ptr;
> + unsigned int i, len;
> +
> + new_ptr = func->old_addr - (void *)_start + vmap_of_xen_text;
> + len = livepatch_insn_len(func) / sizeof(uint32_t);
> + for ( i = 0; i < len; i++ )
> + {
> + uint32_t insn;
> +
> + memcpy(&insn, func->opaque + (i * sizeof(uint32_t)), ARCH_PATCH_INSN_SIZE);
> + /* PATCH! */
> + *(new_ptr + i) = insn;
> + }
here. See the comments on the ARM64 part (i.e patch #5).
> }
Regards,
--
Julien Grall
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next prev parent reply other threads:[~2016-09-27 16:39 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 17:32 [PATCH v5] Livepatch for ARM 64 and 32 Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 01/16] arm64: s/ALTERNATIVE/HAS_ALTERNATIVE/ Konrad Rzeszutek Wilk
2016-09-22 12:21 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 02/16] arm/x86/common: Add HAS_[ALTERNATIVE|EX_TABLE] Konrad Rzeszutek Wilk
2016-09-22 12:23 ` Julien Grall
2016-09-22 15:30 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 03/16] livepatch: Reject payloads with .alternative or .ex_table if support is not built-in Konrad Rzeszutek Wilk
2016-09-23 12:47 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 04/16] arm: poison initmem when it is freed Konrad Rzeszutek Wilk
2016-09-22 12:28 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 05/16] livepatch: Initial ARM64 support Konrad Rzeszutek Wilk
2016-09-22 12:49 ` Julien Grall
2016-09-23 13:38 ` Ross Lagerwall
2016-09-23 15:44 ` Konrad Rzeszutek Wilk
2016-09-27 16:42 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 06/16] livepatch: ARM/x86: Check displacement of old_addr and new_addr Konrad Rzeszutek Wilk
2016-09-22 12:55 ` Julien Grall
2016-09-23 14:36 ` Ross Lagerwall
2016-09-23 15:37 ` Konrad Rzeszutek Wilk
2016-09-23 15:59 ` Konrad Rzeszutek Wilk
2016-09-28 10:21 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 07/16] livepatch: ARM 32|64: Ignore mapping symbols: $[d, a, x] Konrad Rzeszutek Wilk
2016-09-22 12:56 ` Julien Grall
2016-09-23 14:44 ` Ross Lagerwall
2016-09-23 16:13 ` Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 08/16] livepatch/arm/x86: Check payload for for unwelcomed symbols Konrad Rzeszutek Wilk
2016-09-22 13:00 ` Julien Grall
2016-09-23 1:29 ` Konrad Rzeszutek Wilk
2016-09-27 8:49 ` Ross Lagerwall
2016-09-23 14:49 ` Ross Lagerwall
2016-09-23 16:15 ` Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 09/16] livepatch: Move test-cases to their own sub-directory in test Konrad Rzeszutek Wilk
2016-09-22 13:01 ` Julien Grall
2016-09-23 14:51 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 10/16] livepatch: x86, ARM, alternative: Expose FEATURE_LIVEPATCH Konrad Rzeszutek Wilk
2016-09-22 13:03 ` Julien Grall
2016-09-27 9:49 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 11/16] livepatch: tests: Make them compile under ARM64 Konrad Rzeszutek Wilk
2016-09-22 13:10 ` Julien Grall
2016-09-22 19:26 ` Konrad Rzeszutek Wilk
2016-09-23 1:33 ` Konrad Rzeszutek Wilk
2016-09-23 9:50 ` Julien Grall
2016-09-27 9:49 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 12/16] xen/arm32: Add an helper to invalidate all instruction caches Konrad Rzeszutek Wilk
2016-09-22 13:17 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 13/16] bug/x86/arm: Align bug_frames sections Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 14/16] livepatch: Initial ARM32 support Konrad Rzeszutek Wilk
2016-09-27 16:39 ` Julien Grall [this message]
2016-09-27 17:50 ` Konrad Rzeszutek Wilk
2016-09-27 23:13 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 15/16] livepatch, arm[32|64]: Share arch_livepatch_revert Konrad Rzeszutek Wilk
2016-09-23 14:59 ` Ross Lagerwall
2016-09-23 16:15 ` Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 16/16] livepatch: arm[32, 64], x86: NOP test-case Konrad Rzeszutek Wilk
2016-09-22 13:23 ` Julien Grall
2016-09-23 1:35 ` Konrad Rzeszutek Wilk
2016-09-23 9:53 ` Julien Grall
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