From: He Zhe <[email protected]> setup_io_tlb_npages does not check input argument before passing it to isdigit. The argument would be a NULL pointer if "swiotlb", without its value, is set in command line and thus causes the following panic.
PANIC: early exception 0xe3 IP 10:ffffffffbb9b8e9f error 0 cr2 0x0 [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.0-rc3-yocto-standard+ #9 [ 0.000000] RIP: 0010:setup_io_tlb_npages+0xf/0x95 ... [ 0.000000] Call Trace: [ 0.000000] do_early_param+0x57/0x8e [ 0.000000] parse_args+0x208/0x320 [ 0.000000] ? rdinit_setup+0x30/0x30 [ 0.000000] parse_early_options+0x29/0x2d [ 0.000000] ? rdinit_setup+0x30/0x30 [ 0.000000] parse_early_param+0x36/0x4d [ 0.000000] setup_arch+0x336/0x99e [ 0.000000] start_kernel+0x6f/0x4e6 [ 0.000000] x86_64_start_reservations+0x24/0x26 [ 0.000000] x86_64_start_kernel+0x6f/0x72 [ 0.000000] secondary_startup_64+0xa4/0xb0 This patch adds a check to prevent the panic and sets it for 4MB by default. Signed-off-by: He Zhe <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Signed-off-by: He Zhe <[email protected]> --- v2: Set swiotlb for 4MB by default kernel/dma/swiotlb.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 045930e..0e18cd4 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -58,6 +58,9 @@ */ #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT) +#define IO_TLB_DEFAULT_MB 4 +#define IO_TLB_DEFAULT_SLABS ((IO_TLB_DEFAULT_MB<<20) >> IO_TLB_SHIFT) + enum swiotlb_force swiotlb_force; /* @@ -103,6 +106,14 @@ static int late_alloc; static int __init setup_io_tlb_npages(char *str) { + if (!str) { + pr_err("No value provided for swiotlb, " + "set it to %d slabs for %dMB by default.\n", + IO_TLB_DEFAULT_SLABS, IO_TLB_DEFAULT_MB); + io_tlb_nslabs = IO_TLB_DEFAULT_SLABS; + return 0; + } + if (isdigit(*str)) { io_tlb_nslabs = simple_strtoul(str, &str, 0); /* avoid tail segment of size < IO_TLB_SEGSIZE */ -- 2.7.4 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
