On 7/10/24 11:55, Evan Green wrote:
On Mon, Jun 24, 2024 at 5:51 PM Jesse Taube <jesse@xxxxxxxxxxxx> wrote:
Originally, the check_unaligned_access_emulated_all_cpus function
only checked the boot hart. This fixes the function to check all
harts.
Fixes: 71c54b3d169d ("riscv: report misaligned accesses emulation to hwprobe")
Signed-off-by: Jesse Taube <jesse@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
V1 -> V2:
- New patch
V2 -> V3:
- Split patch
---
arch/riscv/kernel/traps_misaligned.c | 23 ++++++-----------------
1 file changed, 6 insertions(+), 17 deletions(-)
diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c
index b62d5a2f4541..8fadbe00dd62 100644
--- a/arch/riscv/kernel/traps_misaligned.c
+++ b/arch/riscv/kernel/traps_misaligned.c
@@ -526,31 +526,17 @@ int handle_misaligned_store(struct pt_regs *regs)
return 0;
}
-static bool check_unaligned_access_emulated(int cpu)
+static void check_unaligned_access_emulated(struct work_struct *unused)
{
+ int cpu = smp_processor_id();
long *mas_ptr = per_cpu_ptr(&misaligned_access_speed, cpu);
unsigned long tmp_var, tmp_val;
- bool misaligned_emu_detected;
*mas_ptr = RISCV_HWPROBE_MISALIGNED_UNKNOWN;
__asm__ __volatile__ (
" "REG_L" %[tmp], 1(%[ptr])\n"
: [tmp] "=r" (tmp_val) : [ptr] "r" (&tmp_var) : "memory");
-
- misaligned_emu_detected = (*mas_ptr == RISCV_HWPROBE_MISALIGNED_EMULATED);
- /*
- * If unaligned_ctl is already set, this means that we detected that all
- * CPUS uses emulated misaligned access at boot time. If that changed
- * when hotplugging the new cpu, this is something we don't handle.
- */
- if (unlikely(unaligned_ctl && !misaligned_emu_detected)) {
- pr_crit("CPU misaligned accesses non homogeneous (expected all emulated)\n");
- while (true)
- cpu_relax();
- }
This chunk was meant to detect and refuse to run on a system where a
heterogeneous CPU is hotplugged into a previously homogenous system.
The commit message doesn't mention this change, how come you
deleted it?
Sorry for the long wait.
I do not remember why I removed this.
Your right it shouldn't be removed, I added it back.
Thanks,
Jesse Taube
-
- return misaligned_emu_detected;
}
bool check_unaligned_access_emulated_all_cpus(void)
@@ -562,8 +548,11 @@ bool check_unaligned_access_emulated_all_cpus(void)
* accesses emulated since tasks requesting such control can run on any
* CPU.
*/
+ schedule_on_each_cpu(check_unaligned_access_emulated);
+
for_each_online_cpu(cpu)
- if (!check_unaligned_access_emulated(cpu))
+ if (per_cpu(misaligned_access_speed, cpu)
+ != RISCV_HWPROBE_MISALIGNED_EMULATED)
return false;
unaligned_ctl = true;
--
2.45.2