ARM: dts: ts7400v2: Remove mmc aliases #58
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There is a long history as to why the aliases were there, they worked on the stock kernel for the TS-7400-V2, did not work in 4.9, and again work in 5.10. The issue is that the U-Boot binary expects the eMMC to be at mmcblk1. This U-Boot was created specifically for the 4.9 kernel. In 5.10 where the alias was honored, it was showing up at mmcblk2 and resulting in a hang waiting for a non-existant device node. Signed-off-by: Kris Bahnsen <[email protected]>
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[ Upstream commit 32019c6 ] When trying to use copy_from_kernel_nofault() to read vsyscall page through a bpf program, the following oops was reported: BUG: unable to handle page fault for address: ffffffffff600000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 3231067 P4D 3231067 PUD 3233067 PMD 3235067 PTE 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 1 PID: 20390 Comm: test_progs ...... 6.7.0+ #58 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) ...... RIP: 0010:copy_from_kernel_nofault+0x6f/0x110 ...... Call Trace: <TASK> ? copy_from_kernel_nofault+0x6f/0x110 bpf_probe_read_kernel+0x1d/0x50 bpf_prog_2061065e56845f08_do_probe_read+0x51/0x8d trace_call_bpf+0xc5/0x1c0 perf_call_bpf_enter.isra.0+0x69/0xb0 perf_syscall_enter+0x13e/0x200 syscall_trace_enter+0x188/0x1c0 do_syscall_64+0xb5/0xe0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 </TASK> ...... ---[ end trace 0000000000000000 ]--- The oops is triggered when: 1) A bpf program uses bpf_probe_read_kernel() to read from the vsyscall page and invokes copy_from_kernel_nofault() which in turn calls __get_user_asm(). 2) Because the vsyscall page address is not readable from kernel space, a page fault exception is triggered accordingly. 3) handle_page_fault() considers the vsyscall page address as a user space address instead of a kernel space address. This results in the fix-up setup by bpf not being applied and a page_fault_oops() is invoked due to SMAP. Considering handle_page_fault() has already considered the vsyscall page address as a userspace address, fix the problem by disallowing vsyscall page read for copy_from_kernel_nofault(). Originally-by: Thomas Gleixner <[email protected]> Reported-by: [email protected] Closes: https://lore.kernel.org/bpf/CAG48ez06TZft=ATH1qh2c5mpS5BT8UakwNkzi6nvK5_djC-4Nw@mail.gmail.com Reported-by: xingwei lee <[email protected]> Closes: https://lore.kernel.org/bpf/CABOYnLynjBoFZOf3Z4BhaZkc5hx_kHfsjiW+UWLoB=w33LvScw@mail.gmail.com Signed-off-by: Hou Tao <[email protected]> Reviewed-by: Sohil Mehta <[email protected]> Acked-by: Thomas Gleixner <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Alexei Starovoitov <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
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There is a long history as to why the aliases were there, they worked on the stock kernel for the TS-7400-V2, did not work in 4.9, and again work in 5.10.
The issue is that the U-Boot binary expects the eMMC to be at mmcblk1. This U-Boot was created specifically for the 4.9 kernel. In 5.10 where the alias was honored, it was showing up at mmcblk2 and resulting in a hang waiting for a non-existant device node.