powerpc/watchpoint: Fix quadword instruction handling on p10 predecessors

[ Upstream commit 4759c11ed20454b7b36db4ec15f7d5aa1519af4a ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index cb424799da0dcf656fd6da6e599a202421706d84..5a00da670a4071a361b8b2f6a18257f253e3cff4 100644 (file)
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -40,6 +40,7 @@ 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 c55e67bab2710c1332a444e5c6e20b4aff8985fa..f39e86d7511446885e37b007608bbf79320f76fa 100644 (file)
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -519,9 +519,17 @@ 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));
 }