parisc: Fix crash when calling PDC_PAT_MEM PDT firmware function

Commit c9c2877d08d9 ("parisc: Add Page Deallocation Table (PDT) support")
introduced the pdc_pat_mem_read_pd_pdt() firmware helper function, which
crashed the system because it trashed the stack if the
pdc_pat_mem_read_pd_retinfo struct was located on the stack (and which is
in size less than the required 32 64-bit values).

Fix it by using the pdc_result struct instead when calling firmware and copy
the return values back into the result struct when finished sucessfully.

While debugging this code I noticed that the pdc_type wasn't set correctly
either, so let's fix that too.

Fixes: c9c2877d08d9 ("parisc: Add Page Deallocation Table (PDT) support")
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/kernel/firmware.c b/arch/parisc/kernel/firmware.c
index 98190252c12fdc801ca8f7f328733727577f48f2..526ed90ca56f4a1b0c6e5339ddca4837d4bc0fbb 100644 (file)
--- a/arch/parisc/kernel/firmware.c
+++ b/arch/parisc/kernel/firmware.c
@@ -1481,12 +1481,19 @@ int pdc_pat_mem_read_pd_pdt(struct pdc_pat_mem_read_pd_retinfo *pret,
                unsigned long offset)
 {
        int retval;
-       unsigned long flags;
+       unsigned long flags, entries;
 
        spin_lock_irqsave(&pdc_lock, flags);
        retval = mem_pdc_call(PDC_PAT_MEM, PDC_PAT_MEM_PD_READ,
-               __pa(&pret), __pa(pdt_entries_ptr),
+               __pa(&pdc_result), __pa(pdt_entries_ptr),
                count, offset);
+
+       if (retval == PDC_OK) {
+               entries = min(pdc_result[0], count);
+               pret->actual_count_bytes = entries;
+               pret->pdt_entries = entries / sizeof(unsigned long);
+       }
+
        spin_unlock_irqrestore(&pdc_lock, flags);
 
        return retval;

diff --git a/arch/parisc/kernel/pdt.c b/arch/parisc/kernel/pdt.c
index f3a797e670b09461b45e1e7163d036fd457beb18..040d49b723d78f785900f64b83eea78e4b65ac33 100644 (file)
--- a/arch/parisc/kernel/pdt.c
+++ b/arch/parisc/kernel/pdt.c
@@ -112,10 +112,12 @@ void __init pdc_pdt_init(void)
 #ifdef CONFIG_64BIT
                struct pdc_pat_mem_read_pd_retinfo pat_pret;
 
+               /* try old obsolete PAT firmware function first */
+               pdt_type = PDT_PAT_OLD;
                ret = pdc_pat_mem_read_cell_pdt(&pat_pret, pdt_entry,
                        MAX_PDT_ENTRIES);
                if (ret != PDC_OK) {
-                       pdt_type = PDT_PAT_OLD;
+                       pdt_type = PDT_PAT_NEW;
                        ret = pdc_pat_mem_read_pd_pdt(&pat_pret, pdt_entry,
                                MAX_PDT_TABLE_SIZE, 0);
                }