From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pf1-f195.google.com ([209.85.210.195]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gx4D3-0000wN-0H for kexec@lists.infradead.org; Fri, 22 Feb 2019 06:21:23 +0000 Received: by mail-pf1-f195.google.com with SMTP id h1so626865pfo.7 for ; Thu, 21 Feb 2019 22:21:19 -0800 (PST) Subject: Re: [PATCH] makedumpfile/arm64: Add support for ARMv8.2-LVA (52-bit user-space VA support) References: <1549569177-7116-1-git-send-email-bhsharma@redhat.com> <4AE2DC15AC0B8543882A74EA0D43DBEC03568114@BPXM09GP.gisp.nec.co.jp> From: Bhupesh Sharma Message-ID: <442e36d2-d7ef-6e42-7f9c-99cb1e6ff1be@redhat.com> Date: Fri, 22 Feb 2019 11:51:12 +0530 MIME-Version: 1.0 In-Reply-To: <4AE2DC15AC0B8543882A74EA0D43DBEC03568114@BPXM09GP.gisp.nec.co.jp> Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: kexec@lists.infradead.org, Kazuhito Hagio Cc: Bhupesh SHARMA Hi Kazu, On 02/12/2019 03:33 AM, Kazuhito Hagio wrote: > Hi Bhupesh, > > On 2/7/2019 2:52 PM, Bhupesh Sharma wrote: >> With ARMv8.2-LVA architecture extension availability, arm64 hardware >> which supports this extension can support upto 52-bit virtual >> addresses. It is specially useful for having a 52-bit user-space virtual >> address space while the kernel can still retain 48-bit virtual >> addresses. >> >> Since at the moment we enable the support of this extensions in the >> kernel via a CONFIG flags (CONFIG_ARM64_USER_VA_BITS_52), so there are >> no clear mechanisms in user-space to determine this CONFIG >> flag value and use it to determine the PA address range values. >> >> 'makedumpfile' can instead use 'MAX_USER_VA_BITS' value to >> determine the maximum virtual physical address supported by user-space. >> If 'MAX_USER_VA_BITS' value is greater than 'VA_BITS' than we might be >> running a use-case where user-space is 52-bit and underlying kernel is >> still 48-bit. The increased 'PTRS_PER_PGD' value for such cases can then >> be calculated as is done by the underlying kernel (see kernel file >> 'arch/arm64/include/asm/pgtable-hwdef.h' for details): > > Thank you for the patch. > I can't test the config yet, but this looks necessary. I am sorry, this review email somehow did not show up in my inbox. >> >> I have sent a kernel patch upstream to add 'MAX_USER_VA_BITS' to >> vmcoreinfo for arm64 (see [0]). >> >> This patch is in accordance with ARMv8 Architecture Reference Manual >> version D.a >> >> [0]. >> http://lists.infradead.org/pipermail/kexec/2019-February/022411.html >> >> Signed-off-by: Bhupesh Sharma >> --- >> arch/arm64.c | 105 +++++++++++++++++++++++++++++++++++++++++---------------- >> makedumpfile.c | 2 ++ >> makedumpfile.h | 1 + >> 3 files changed, 79 insertions(+), 29 deletions(-) >> >> diff --git a/arch/arm64.c b/arch/arm64.c >> index a1db7dc63107..b522e93f4e80 100644 >> --- a/arch/arm64.c >> +++ b/arch/arm64.c >> @@ -47,6 +47,7 @@ typedef struct { >> static int lpa_52_bit_support_available; >> static int pgtable_level; >> static int va_bits; >> +static int max_user_va_bits; >> static unsigned long kimage_voffset; >> >> #define SZ_4K 4096 >> @@ -145,7 +146,7 @@ get_page_table_level_arm64(void) >> #define PGDIR_SHIFT ARM64_HW_PGTABLE_LEVEL_SHIFT(4 - (get_page_table_level_arm64())) >> #define PGDIR_SIZE (_AC(1, UL) << PGDIR_SHIFT) >> #define PGDIR_MASK (~(PGDIR_SIZE-1)) >> -#define PTRS_PER_PGD (1 << ((va_bits) - PGDIR_SHIFT)) >> +#define PTRS_PER_PGD (1 << ((max_user_va_bits) - PGDIR_SHIFT)) >> >> /* >> * Section address mask and size definitions. >> @@ -478,6 +479,46 @@ get_stext_symbol(void) >> return(found ? kallsym : FALSE); >> } >> >> +static int >> +get_va_bits_from_stext_arm64(void) >> +{ >> + ulong _stext; >> + >> + _stext = get_stext_symbol(); >> + if (!_stext) { >> + ERRMSG("Can't get the symbol of _stext.\n"); >> + return FALSE; >> + } >> + >> + /* Derive va_bits as per arch/arm64/Kconfig */ >> + if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) { >> + va_bits = 36; >> + } else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) { >> + va_bits = 39; >> + } else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) { >> + va_bits = 42; >> + } else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) { >> + va_bits = 47; >> + } else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) { >> + va_bits = 48; >> + } else { >> + ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n"); >> + return FALSE; >> + } >> + >> + DEBUG_MSG("va_bits : %d\n", va_bits); > > Please add "(_stext)" to the end of line for debugging. Ok, will address in v3. >> + >> + return TRUE; >> +} >> + >> +static void >> +get_page_offset_arm64(void) >> +{ >> + info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1); >> + >> + DEBUG_MSG("page_offset : %lx\n", info->page_offset); >> +} >> + >> int >> get_machdep_info_arm64(void) >> { >> @@ -493,8 +534,37 @@ get_machdep_info_arm64(void) >> /* Check if va_bits is still not initialized. If still 0, call >> * get_versiondep_info() to initialize the same. >> */ >> + if (NUMBER(VA_BITS) != NOT_FOUND_NUMBER) { >> + va_bits = NUMBER(VA_BITS); >> + DEBUG_MSG("va_bits : %d (vmcoreinfo)\n", >> + va_bits); >> + } >> + >> + /* Check if va_bits is still not initialized. If still 0, call >> + * get_versiondep_info() to initialize the same from _stext >> + * symbol. >> + */ >> if (!va_bits) >> - get_versiondep_info_arm64(); >> + if (get_va_bits_from_stext_arm64() == ERROR) >> + return ERROR; > > These ERRORs should be FALSE. Ok, will address in v3. >> + >> + get_page_offset_arm64(); >> + >> + if (NUMBER(MAX_USER_VA_BITS) != NOT_FOUND_NUMBER) { >> + max_user_va_bits = NUMBER(MAX_USER_VA_BITS); >> + DEBUG_MSG("max_user_va_bits : %d (vmcoreinfo)\n", >> + max_user_va_bits); >> + } >> + >> + /* Check if max_user_va_bits is still not initialized. >> + * If still 0, its not available in vmcoreinfo and its >> + * safe to initialize it with va_bits. >> + */ >> + if (!max_user_va_bits) { >> + max_user_va_bits = va_bits; >> + DEBUG_MSG("max_user_va_bits : %d (default = va_bits)\n", >> + max_user_va_bits); >> + } >> >> if (!calculate_plat_config()) { >> ERRMSG("Can't determine platform config values\n"); >> @@ -533,34 +603,11 @@ get_xen_info_arm64(void) >> int >> get_versiondep_info_arm64(void) >> { >> - ulong _stext; >> - >> - _stext = get_stext_symbol(); >> - if (!_stext) { >> - ERRMSG("Can't get the symbol of _stext.\n"); >> - return FALSE; >> - } >> - >> - /* Derive va_bits as per arch/arm64/Kconfig */ >> - if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) { >> - va_bits = 36; >> - } else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) { >> - va_bits = 39; >> - } else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) { >> - va_bits = 42; >> - } else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) { >> - va_bits = 47; >> - } else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) { >> - va_bits = 48; >> - } else { >> - ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n"); >> - return FALSE; >> - } >> - >> - info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1); >> + if (!va_bits) >> + if (get_va_bits_from_stext_arm64() == ERROR) >> + return ERROR; > > Same as above. Ok, will address in v3. Thanks, Bhupesh _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec