Hi Arnd, Do you know when you will be able to add GCC 15 to https://mirrors.edge.kernel.org/pub/tools/crosstool/ ?
Thanks Christophe Le 10/05/2025 à 03:35, Paul Mackerras a écrit : > Running Linux on Microwatt with a kernel compiled on an x86-64 system > running Fedora 42 (using the packaged cross-compiler, i.e. the > gcc-powerpcle64-linux-gnu package), I'm seeing a crash like this: > > [ 0.141591] smp: Bringing up secondary CPUs ... > [ 0.167628] BUG: Unable to handle kernel data access on write at > 0xc00a0000be8d6004 > [ 0.175409] Faulting instruction address: 0xc00000000000fcb4 > cpu 0x0: Vector: 300 (Data Access) at [c0000000012f78d0] > pc: c00000000000fcb4: __do_IRQ+0x64/0x84 > lr: c00000000000fccc: __do_IRQ+0x7c/0x84 > sp: c0000000012f7b70 > msr: 9000000000001033 > dar: c00a0000be8d6004 > dsisr: 42000000 > current = 0xc0000000012de000 > paca = 0xc00000000135d000 irqmask: 0x03 irq_happened: 0x01 > pid = 0, comm = swapper/0 > Linux version 6.15.0-rc1-00001-g72b73737d483-dirty (paulus@thinks) > (powerpc64le-linux-gnu-gcc (GCC) 15.0.1 20250329 (Red Hat Cross 15.0.1-0), > GNU ld version 2.44-1.fc42) #5 SMP Thu May 8 22:20:34 AEST 2025 > enter ? for help > [c0000000012f7b70] c00000000000fd50 do_IRQ+0x7c/0x90 (unreliable) > [c0000000012f7ba0] c000000000007db4 hardware_interrupt_common_virt+0x1c4/0x1d0 > --- Exception: 500 (Hardware Interrupt) at c00000000001c2ec > arch_local_irq_restore+0x60/0xc4 > [c0000000012f7ea0] c000000000083c68 do_idle+0xd4/0xf4 > [c0000000012f7ee0] c000000000083e08 cpu_startup_entry+0x34/0x38 > [c0000000012f7f10] c00000000000cc7c kernel_init+0x0/0x144 > [c0000000012f7f40] c000000001000ecc do_one_initcall+0x0/0x160 > [c0000000012f7fe0] c00000000000ba6c start_here_common+0x1c/0x20 > 0:mon> > > What's happening is that gcc 15 seems to be using r2 as an ordinary > register, and r2 has a live value in it at the point where __do_IRQ() > calls call_do_irq(). Since r2 is not in the clobber list for the > inline asm in call_do_irq(), it doesn't get saved and restored around > the call to __do_irq(), and when we come back to __do_IRQ(), it has > been modified. Then when __do_IRQ() subsequently does a store using > r2, it blows up like the above. > > Adding r2 to the clobber list in call_do_irq() fixes it. Does this > seem like the right fix? Does it need to be conditional on the gcc > version? Or is there a better way to fix the problem? > > Thanks, > Paul. >
