+++ /dev/null
-From 38f07a07c25be6fe84adf5b6557aa42c3fbe56e0 Mon Sep 17 00:00:00 2001
-From: Sasha Levin <sashal@kernel.org>
-Date: Tue, 18 Sep 2018 09:26:03 +0000
-Subject: powerpc/kgdb: add kgdb_arch_set/remove_breakpoint()
-
-From: Christophe Leroy <christophe.leroy@c-s.fr>
-
-[ Upstream commit fb978ca207743badfe7efd9eebe68bcbb4969f79 ]
-
-Generic implementation fails to remove breakpoints after init
-when CONFIG_STRICT_KERNEL_RWX is selected:
-
-[ 13.251285] KGDB: BP remove failed: c001c338
-[ 13.259587] kgdbts: ERROR PUT: end of test buffer on 'do_fork_test' line 8 expected OK got $E14#aa
-[ 13.268969] KGDB: re-enter exception: ALL breakpoints killed
-[ 13.275099] CPU: 0 PID: 1 Comm: init Not tainted 4.18.0-g82bbb913ffd8 #860
-[ 13.282836] Call Trace:
-[ 13.285313] [c60e1ba0] [c0080ef0] kgdb_handle_exception+0x6f4/0x720 (unreliable)
-[ 13.292618] [c60e1c30] [c000e97c] kgdb_handle_breakpoint+0x3c/0x98
-[ 13.298709] [c60e1c40] [c000af54] program_check_exception+0x104/0x700
-[ 13.305083] [c60e1c60] [c000e45c] ret_from_except_full+0x0/0x4
-[ 13.310845] [c60e1d20] [c02a22ac] run_simple_test+0x2b4/0x2d4
-[ 13.316532] [c60e1d30] [c0081698] put_packet+0xb8/0x158
-[ 13.321694] [c60e1d60] [c00820b4] gdb_serial_stub+0x230/0xc4c
-[ 13.327374] [c60e1dc0] [c0080af8] kgdb_handle_exception+0x2fc/0x720
-[ 13.333573] [c60e1e50] [c000e928] kgdb_singlestep+0xb4/0xcc
-[ 13.339068] [c60e1e70] [c000ae1c] single_step_exception+0x90/0xac
-[ 13.345100] [c60e1e80] [c000e45c] ret_from_except_full+0x0/0x4
-[ 13.350865] [c60e1f40] [c000e11c] ret_from_syscall+0x0/0x38
-[ 13.356346] Kernel panic - not syncing: Recursive entry to debugger
-
-This patch creates powerpc specific version of
-kgdb_arch_set_breakpoint() and kgdb_arch_remove_breakpoint()
-using patch_instruction()
-
-Fixes: 1e0fc9d1eb2b ("powerpc/Kconfig: Enable STRICT_KERNEL_RWX for some configs")
-Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
-Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
-Signed-off-by: Sasha Levin <sashal@kernel.org>
----
- arch/powerpc/include/asm/kgdb.h | 5 +++-
- arch/powerpc/kernel/kgdb.c | 43 +++++++++++++++++++++++++++------
- 2 files changed, 39 insertions(+), 9 deletions(-)
-
-diff --git a/arch/powerpc/include/asm/kgdb.h b/arch/powerpc/include/asm/kgdb.h
-index 9db24e77b9f4b..a9e098a3b881f 100644
---- a/arch/powerpc/include/asm/kgdb.h
-+++ b/arch/powerpc/include/asm/kgdb.h
-@@ -26,9 +26,12 @@
- #define BREAK_INSTR_SIZE 4
- #define BUFMAX ((NUMREGBYTES * 2) + 512)
- #define OUTBUFMAX ((NUMREGBYTES * 2) + 512)
-+
-+#define BREAK_INSTR 0x7d821008 /* twge r2, r2 */
-+
- static inline void arch_kgdb_breakpoint(void)
- {
-- asm(".long 0x7d821008"); /* twge r2, r2 */
-+ asm(stringify_in_c(.long BREAK_INSTR));
- }
- #define CACHE_FLUSH_IS_SAFE 1
- #define DBG_MAX_REG_NUM 70
-diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
-index 35e240a0a4087..59c578f865aa6 100644
---- a/arch/powerpc/kernel/kgdb.c
-+++ b/arch/powerpc/kernel/kgdb.c
-@@ -24,6 +24,7 @@
- #include <asm/processor.h>
- #include <asm/machdep.h>
- #include <asm/debug.h>
-+#include <asm/code-patching.h>
- #include <linux/slab.h>
-
- /*
-@@ -144,7 +145,7 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs)
- if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0)
- return 0;
-
-- if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr))
-+ if (*(u32 *)regs->nip == BREAK_INSTR)
- regs->nip += BREAK_INSTR_SIZE;
-
- return 1;
-@@ -441,16 +442,42 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
- return -1;
- }
-
-+int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
-+{
-+ int err;
-+ unsigned int instr;
-+ unsigned int *addr = (unsigned int *)bpt->bpt_addr;
-+
-+ err = probe_kernel_address(addr, instr);
-+ if (err)
-+ return err;
-+
-+ err = patch_instruction(addr, BREAK_INSTR);
-+ if (err)
-+ return -EFAULT;
-+
-+ *(unsigned int *)bpt->saved_instr = instr;
-+
-+ return 0;
-+}
-+
-+int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
-+{
-+ int err;
-+ unsigned int instr = *(unsigned int *)bpt->saved_instr;
-+ unsigned int *addr = (unsigned int *)bpt->bpt_addr;
-+
-+ err = patch_instruction(addr, instr);
-+ if (err)
-+ return -EFAULT;
-+
-+ return 0;
-+}
-+
- /*
- * Global data
- */
--struct kgdb_arch arch_kgdb_ops = {
--#ifdef __LITTLE_ENDIAN__
-- .gdb_bpt_instr = {0x08, 0x10, 0x82, 0x7d},
--#else
-- .gdb_bpt_instr = {0x7d, 0x82, 0x10, 0x08},
--#endif
--};
-+struct kgdb_arch arch_kgdb_ops;
-
- static int kgdb_not_implemented(struct pt_regs *regs)
- {
---
-2.20.1
-