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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-08 16:59:34 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-08 16:59:34 -0700 |
commit | a1aab6f3d295f078c008893ee7fa2c011626c46f (patch) | |
tree | 1ae344c8ed1b1dc531be1ae99188c180ad0c6c7c /arch/x86/kernel/ftrace_32.S | |
parent | dad1c12ed831a7a89cc01e5582cd0b81a4be7f19 (diff) | |
parent | 7457c0da024b181a9143988d740001f9bc98698d (diff) | |
download | linux-a1aab6f3d295f078c008893ee7fa2c011626c46f.tar.bz2 |
Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar:
"Most of the changes relate to Peter Zijlstra's cleanup of ptregs
handling, in particular the i386 part is now much simplified and
standardized - no more partial ptregs stack frames via the esp/ss
oddity. This simplifies ftrace, kprobes, the unwinder, ptrace, kdump
and kgdb.
There's also a CR4 hardening enhancements by Kees Cook, to make the
generic platform functions such as native_write_cr4() less useful as
ROP gadgets that disable SMEP/SMAP. Also protect the WP bit of CR0
against similar attacks.
The rest is smaller cleanups/fixes"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/alternatives: Add int3_emulate_call() selftest
x86/stackframe/32: Allow int3_emulate_push()
x86/stackframe/32: Provide consistent pt_regs
x86/stackframe, x86/ftrace: Add pt_regs frame annotations
x86/stackframe, x86/kprobes: Fix frame pointer annotations
x86/stackframe: Move ENCODE_FRAME_POINTER to asm/frame.h
x86/entry/32: Clean up return from interrupt preemption path
x86/asm: Pin sensitive CR0 bits
x86/asm: Pin sensitive CR4 bits
Documentation/x86: Fix path to entry_32.S
x86/asm: Remove unused TASK_TI_flags from asm-offsets.c
Diffstat (limited to 'arch/x86/kernel/ftrace_32.S')
-rw-r--r-- | arch/x86/kernel/ftrace_32.S | 78 |
1 files changed, 45 insertions, 33 deletions
diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S index 2ba914a34b06..073aab525d80 100644 --- a/arch/x86/kernel/ftrace_32.S +++ b/arch/x86/kernel/ftrace_32.S @@ -9,6 +9,8 @@ #include <asm/export.h> #include <asm/ftrace.h> #include <asm/nospec-branch.h> +#include <asm/frame.h> +#include <asm/asm-offsets.h> # define function_hook __fentry__ EXPORT_SYMBOL(__fentry__) @@ -89,26 +91,38 @@ END(ftrace_caller) ENTRY(ftrace_regs_caller) /* - * i386 does not save SS and ESP when coming from kernel. - * Instead, to get sp, ®s->sp is used (see ptrace.h). - * Unfortunately, that means eflags must be at the same location - * as the current return ip is. We move the return ip into the - * regs->ip location, and move flags into the return ip location. + * We're here from an mcount/fentry CALL, and the stack frame looks like: + * + * <previous context> + * RET-IP + * + * The purpose of this function is to call out in an emulated INT3 + * environment with a stack frame like: + * + * <previous context> + * gap / RET-IP + * gap + * gap + * gap + * pt_regs + * + * We do _NOT_ restore: ss, flags, cs, gs, fs, es, ds */ - pushl $__KERNEL_CS - pushl 4(%esp) /* Save the return ip */ - pushl $0 /* Load 0 into orig_ax */ + subl $3*4, %esp # RET-IP + 3 gaps + pushl %ss # ss + pushl %esp # points at ss + addl $5*4, (%esp) # make it point at <previous context> + pushfl # flags + pushl $__KERNEL_CS # cs + pushl 7*4(%esp) # ip <- RET-IP + pushl $0 # orig_eax + pushl %gs pushl %fs pushl %es pushl %ds - pushl %eax - - /* Get flags and place them into the return ip slot */ - pushf - popl %eax - movl %eax, 8*4(%esp) + pushl %eax pushl %ebp pushl %edi pushl %esi @@ -116,24 +130,27 @@ ENTRY(ftrace_regs_caller) pushl %ecx pushl %ebx - movl 12*4(%esp), %eax /* Load ip (1st parameter) */ - subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */ - movl 15*4(%esp), %edx /* Load parent ip (2nd parameter) */ - movl function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */ - pushl %esp /* Save pt_regs as 4th parameter */ + ENCODE_FRAME_POINTER + + movl PT_EIP(%esp), %eax # 1st argument: IP + subl $MCOUNT_INSN_SIZE, %eax + movl 21*4(%esp), %edx # 2nd argument: parent ip + movl function_trace_op, %ecx # 3rd argument: ftrace_pos + pushl %esp # 4th argument: pt_regs GLOBAL(ftrace_regs_call) call ftrace_stub - addl $4, %esp /* Skip pt_regs */ + addl $4, %esp # skip 4th argument - /* restore flags */ - push 14*4(%esp) - popf + /* place IP below the new SP */ + movl PT_OLDESP(%esp), %eax + movl PT_EIP(%esp), %ecx + movl %ecx, -4(%eax) - /* Move return ip back to its original location */ - movl 12*4(%esp), %eax - movl %eax, 14*4(%esp) + /* place EAX below that */ + movl PT_EAX(%esp), %ecx + movl %ecx, -8(%eax) popl %ebx popl %ecx @@ -141,14 +158,9 @@ GLOBAL(ftrace_regs_call) popl %esi popl %edi popl %ebp - popl %eax - popl %ds - popl %es - popl %fs - popl %gs - /* use lea to not affect flags */ - lea 3*4(%esp), %esp /* Skip orig_ax, ip and cs */ + lea -8(%eax), %esp + popl %eax jmp .Lftrace_ret |