[PATCH AUTOSEL 6.6 45/47] LoongArch: Apply dynamic relocations for LLD

[PATCH AUTOSEL 6.6 45/47] LoongArch: Apply dynamic relocations for LLD

[Sasha Levin]

From: WANG Rui <wangrui@loongson.cn>

[ Upstream commit eea673e9d5ea994c60b550ffb684413d3759b3f4 ]

For the following assembly code:

     .text
     .global func
 func:
     nop

     .data
 var:
     .dword func

When linked with `-pie`, GNU LD populates the `var` variable with the
pre-relocated value of `func`. However, LLVM LLD does not exhibit the
same behavior. This issue also arises with the `kernel_entry` in arch/
loongarch/kernel/head.S:

 _head:
     .word   MZ_MAGIC                /* "MZ", MS-DOS header */
     .org    0x8
     .dword  kernel_entry            /* Kernel entry point */

The correct kernel entry from the MS-DOS header is crucial for jumping
to vmlinux from zboot. This necessity is why the compressed relocatable
kernel compiled by Clang encounters difficulties in booting.

To address this problem, it is proposed to apply dynamic relocations to
place with `--apply-dynamic-relocs`.

Link: https://github.com/ClangBuiltLinux/linux/issues/1962
Signed-off-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/loongarch/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index fb0fada43197e..390867fc45b84 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -80,7 +80,7 @@ endif
 
 ifeq ($(CONFIG_RELOCATABLE),y)
 KBUILD_CFLAGS_KERNEL		+= -fPIE
-LDFLAGS_vmlinux			+= -static -pie --no-dynamic-linker -z notext
+LDFLAGS_vmlinux			+= -static -pie --no-dynamic-linker -z notext $(call ld-option, --apply-dynamic-relocs)
 endif
 
 cflags-y += $(call cc-option, -mno-check-zero-division)
-- 
2.42.0

[PATCH AUTOSEL 6.6 46/47] LoongArch: Set unwind stack type to unknown rather than set error flag

[Sasha Levin]

From: Jinyang He <hejinyang@loongson.cn>

[ Upstream commit 97ceddbc9404a7d1e2c4049435bff29427d762cc ]

During unwinding, unwind_done() is used as an end condition. Normally it
unwind to the user stack and then set the stack type to unknown, which
is a normal exit. When something unexpected happens in unwind process
and we cannot unwind anymore, we should set the error flag, and also set
the stack type to unknown to indicate that the unwind process can not
continue. The error flag emphasizes that the unwind process produce an
unexpected error. There is no unexpected things when we unwind the PT_REGS
in the top of IRQ stack and find out that is an user mode PT_REGS. Thus,
we should not set error flag and just set stack type to unknown.

Reported-by: Hengqi Chen <hengqi.chen@gmail.com>
Acked-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/loongarch/kernel/stacktrace.c      | 2 +-
 arch/loongarch/kernel/unwind.c          | 1 -
 arch/loongarch/kernel/unwind_prologue.c | 2 +-
 3 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/stacktrace.c
index 92270f14db948..f623feb2129f1 100644
--- a/arch/loongarch/kernel/stacktrace.c
+++ b/arch/loongarch/kernel/stacktrace.c
@@ -32,7 +32,7 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 	}
 
 	for (unwind_start(&state, task, regs);
-	     !unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) {
+	     !unwind_done(&state); unwind_next_frame(&state)) {
 		addr = unwind_get_return_address(&state);
 		if (!addr || !consume_entry(cookie, addr))
 			break;
diff --git a/arch/loongarch/kernel/unwind.c b/arch/loongarch/kernel/unwind.c
index ba324ba76fa15..a463d6961344c 100644
--- a/arch/loongarch/kernel/unwind.c
+++ b/arch/loongarch/kernel/unwind.c
@@ -28,6 +28,5 @@ bool default_next_frame(struct unwind_state *state)
 
 	} while (!get_stack_info(state->sp, state->task, info));
 
-	state->error = true;
 	return false;
 }
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index 55afc27320e12..929ae240280a5 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -227,7 +227,7 @@ static bool next_frame(struct unwind_state *state)
 	} while (!get_stack_info(state->sp, state->task, info));
 
 out:
-	state->error = true;
+	state->stack_info.type = STACK_TYPE_UNKNOWN;
 	return false;
 }
 
-- 
2.42.0

[PATCH AUTOSEL 6.6 47/47] LoongArch: Preserve syscall nr across execve()

[Sasha Levin]

From: Hengqi Chen <hengqi.chen@gmail.com>

[ Upstream commit d6c5f06e46a836e6a70c7cfd95bb38a67d9252ec ]

Currently, we store syscall nr in pt_regs::regs[11] and syscall execve()
accidentally overrides it during its execution:

    sys_execve()
      -> do_execve()
        -> do_execveat_common()
          -> bprm_execve()
            -> exec_binprm()
              -> search_binary_handler()
                -> load_elf_binary()
                  -> ELF_PLAT_INIT()

ELF_PLAT_INIT() reset regs[11] to 0, so in syscall_exit_to_user_mode()
we later get a wrong syscall nr. This breaks tools like execsnoop since
it relies on execve() tracepoints.

Skip pt_regs::regs[11] reset in ELF_PLAT_INIT() to fix the issue.

Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/loongarch/include/asm/elf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/loongarch/include/asm/elf.h b/arch/loongarch/include/asm/elf.h
index b9a4ab54285c1..9b16a3b8e7060 100644
--- a/arch/loongarch/include/asm/elf.h
+++ b/arch/loongarch/include/asm/elf.h
@@ -293,7 +293,7 @@ extern const char *__elf_platform;
 #define ELF_PLAT_INIT(_r, load_addr)	do { \
 	_r->regs[1] = _r->regs[2] = _r->regs[3] = _r->regs[4] = 0;	\
 	_r->regs[5] = _r->regs[6] = _r->regs[7] = _r->regs[8] = 0;	\
-	_r->regs[9] = _r->regs[10] = _r->regs[11] = _r->regs[12] = 0;	\
+	_r->regs[9] = _r->regs[10] /* syscall n */ = _r->regs[12] = 0;	\
 	_r->regs[13] = _r->regs[14] = _r->regs[15] = _r->regs[16] = 0;	\
 	_r->regs[17] = _r->regs[18] = _r->regs[19] = _r->regs[20] = 0;	\
 	_r->regs[21] = _r->regs[22] = _r->regs[23] = _r->regs[24] = 0;	\
-- 
2.42.0