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Wed, 29 Apr 2026 05:28:12 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface MIME-Version: 1.0 Date: Wed, 29 Apr 2026 11:27:01 +0200 From: "Ard Biesheuvel" To: "zhaoyang.huang" , "Catalin Marinas" , "Will Deacon" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, "Zhaoyang Huang" , steve.kang@unisoc.com Message-Id: <8fcde357-aaa1-4bd2-a8b3-d660b94a38c6@app.fastmail.com> In-Reply-To: <20260429061752.2880923-1-zhaoyang.huang@unisoc.com> References: <20260429061752.2880923-1-zhaoyang.huang@unisoc.com> Subject: Re: [PATCH] arch: arm64: fix KERNEL_SEGMENT_COUNT error Content-Type: text/plain Content-Transfer-Encoding: 7bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hello Zhaoyang, On Wed, 29 Apr 2026, at 08:17, zhaoyang.huang wrote: > From: Zhaoyang Huang > > During debug of a kernel panic, we find that the pte_t of the final > part of [data, end] segment got overflow to the next page of > init_pg_end[1] which is the gap page before early_init_stack[2]. > This should be introduced by the KERNEL_SEGMENT_COUNT's value is 5 > which should be 6 as map_segment are called 6 times for the segments > of (text, stext, rodata, inittext, initdata, data+bss) > > [1] > crash_arm64_v9.0.1> vtop ffffffed00601000 > VIRTUAL PHYSICAL > ffffffed00601000 83401000 > > PAGE DIRECTORY: ffffffecffd62000 > PGD: ffffffecffd62da0 => 10000000833fb003 > PMD: ffffff80033fb018 => 10000000833fe003 > PTE: ffffff80033fe008 => 68000083401f03 > PAGE: 83401000 > > PTE PHYSICAL FLAGS > 68000083401f03 83401000 (VALID|SHARED|AF|NG|PXN|UXN) > > PAGE PHYSICAL MAPPING INDEX CNT FLAGS > fffffffec00d0040 83401000 0 0 1 4000 reserved > > [2] > ffffffed002c8000 (r) __pi__data > ffffffed0054e000 (d) __pi___bss_start > ffffffed005f5000 (b) __pi_init_pg_dir > ffffffed005fe000 (b) __pi_init_pg_end > ffffffed005ff000 (B) early_init_stack > ffffffed00608000 (b) __pi__end > > Signed-off-by: Zhaoyang Huang > --- > arch/arm64/include/asm/kernel-pgtable.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kernel-pgtable.h > b/arch/arm64/include/asm/kernel-pgtable.h > index 74a4f738c5f5..14dd1c52552a 100644 > --- a/arch/arm64/include/asm/kernel-pgtable.h > +++ b/arch/arm64/include/asm/kernel-pgtable.h > @@ -64,8 +64,8 @@ > #define INIT_IDMAP_FDT_PAGES (EARLY_PAGES(INIT_IDMAP_PGTABLE_LEVELS, > 0UL, UL(MAX_FDT_SIZE), 1) - 1) > #define INIT_IDMAP_FDT_SIZE ((INIT_IDMAP_FDT_PAGES + > EARLY_IDMAP_EXTRA_FDT_PAGES) * PAGE_SIZE) > > -/* The number of segments in the kernel image (text, rodata, inittext, > initdata, data+bss) */ > -#define KERNEL_SEGMENT_COUNT 5 > +/* The number of segments in the kernel image (text, stext, rodata, > inittext, initdata, data+bss) */ > +#define KERNEL_SEGMENT_COUNT 6 > > #if SWAPPER_BLOCK_SIZE > SEGMENT_ALIGN > #define EARLY_SEGMENT_EXTRA_PAGES (KERNEL_SEGMENT_COUNT + 1) I think the better fix would be --- a/arch/arm64/include/asm/kernel-pgtable.h +++ b/arch/arm64/include/asm/kernel-pgtable.h @@ -68,7 +68,7 @@ #define KERNEL_SEGMENT_COUNT 5 #if SWAPPER_BLOCK_SIZE > SEGMENT_ALIGN -#define EARLY_SEGMENT_EXTRA_PAGES (KERNEL_SEGMENT_COUNT + 1) +#define EARLY_SEGMENT_EXTRA_PAGES (KERNEL_SEGMENT_COUNT + 2) /* * The initial ID map consists of the kernel image, mapped as two separate * segments, and may appear misaligned wrt the swapper block size. This means and add a line Fixes: 5973a62efa34 ("arm64: map [_text, _stext) virtual address range non-executable+read-only")