powerpc/watchpoint: Fix quadword instruction handling on p10 predecessors

On p10 predecessors, watchpoint with quadword access is compared at
quadword length. If the watch range is doubleword or less than that
in a first half of quadword aligned 16 bytes, and if there is any
unaligned quadword access which will access only the 2nd half, the
handler should consider it as extraneous and emulate/single-step it
before continuing.

Fixes: 74c6881019b7 ("powerpc/watchpoint: Prepare handler to handle more than one watchpoint")
Reported-by: Pedro Miraglia Franco de Carvalho <pedromfc@linux.ibm.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200902042945.129369-2-ravi.bangoria@linux.ibm.com

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index db206a7f38e24e3024f81dda37b430dce3794259..9b68eafebf4399b14a7b42e820dbb00bd9cf2aaa 100644 (file)
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -42,6 +42,7 @@ struct arch_hw_breakpoint {
 #else
 #define HW_BREAKPOINT_SIZE  0x8
 #endif
+#define HW_BREAKPOINT_SIZE_QUADWORD    0x10
 
 #define DABR_MAX_LEN   8
 #define DAWR_MAX_LEN   512

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 1f4a1efa00744990143299802719827dffb02abd..9f7df1c372330ea9b342fc66d18f13e4da82cbab 100644 (file)
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -520,9 +520,17 @@ static bool ea_hw_range_overlaps(unsigned long ea, int size,
                                 struct arch_hw_breakpoint *info)
 {
        unsigned long hw_start_addr, hw_end_addr;
+       unsigned long align_size = HW_BREAKPOINT_SIZE;
 
-       hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
-       hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE);
+       /*
+        * On p10 predecessors, quadword is handle differently then
+        * other instructions.
+        */
+       if (!cpu_has_feature(CPU_FTR_ARCH_31) && size == 16)
+               align_size = HW_BREAKPOINT_SIZE_QUADWORD;
+
+       hw_start_addr = ALIGN_DOWN(info->address, align_size);
+       hw_end_addr = ALIGN(info->address + info->len, align_size);
 
        return ((ea < hw_end_addr) && (ea + size > hw_start_addr));
 }