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authorMax Filippov <jcmvbkbc@gmail.com>2016-01-24 10:32:10 +0300
committerChris Zankel <chris@zankel.net>2016-03-11 08:53:32 +0000
commitc91e02bd9702f2c00c6a6dc82dec1b2d5bb9f039 (patch)
tree7ffa9530078b594c2ad0ea97259abe15e9dd9619 /arch/xtensa/kernel/process.c
parent6ec7026ac01f3db039e0428db1f37590685ad3e7 (diff)
xtensa: support hardware breakpoints/watchpoints
Use perf framework to manage hardware instruction and data breakpoints. Add two new ptrace calls: PTRACE_GETHBPREGS and PTRACE_SETHBPREGS to query and set instruction and data breakpoints. Address bit 0 choose instruction (0) or data (1) break register, bits 31..1 are the register number. Both calls transfer two 32-bit words: address (0) and control (1). Instruction breakpoint contorl word is 0 to clear breakpoint, 1 to set. Data breakpoint control word bit 31 is 'trigger on store', bit 30 is 'trigger on load, bits 29..0 are length. Length 0 is used to clear a breakpoint. To set a breakpoint length must be a power of 2 in the range 1..64 and the address must be length-aligned. Introduce new thread_info flag: TIF_DB_DISABLED. Set it if debug exception is raised by the kernel code accessing watched userspace address and disable corresponding data breakpoint. On exit to userspace check that flag and, if set, restore all data breakpoints. Handle debug exceptions raised with PS.EXCM set. This may happen when window overflow/underflow handler or fast exception handler hits data breakpoint, in which case save and disable all data breakpoints, single-step faulting instruction and restore data breakpoints. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Diffstat (limited to 'arch/xtensa/kernel/process.c')
-rw-r--r--arch/xtensa/kernel/process.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 1c85323f01d7..5bbfed81c97b 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -24,6 +24,7 @@
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/elf.h>
+#include <linux/hw_breakpoint.h>
#include <linux/init.h>
#include <linux/prctl.h>
#include <linux/init_task.h>
@@ -43,6 +44,7 @@
#include <linux/atomic.h>
#include <asm/asm-offsets.h>
#include <asm/regs.h>
+#include <asm/hw_breakpoint.h>
extern void ret_from_fork(void);
extern void ret_from_kernel_thread(void);
@@ -131,6 +133,7 @@ void flush_thread(void)
coprocessor_flush_all(ti);
coprocessor_release_all(ti);
#endif
+ flush_ptrace_hw_breakpoint(current);
}
/*
@@ -273,6 +276,8 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
ti->cpenable = 0;
#endif
+ clear_ptrace_hw_breakpoint(p);
+
return 0;
}