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08 September 2024, 02:26:05 UTC
Revision 84c6f6046c5a2189160a8f0dca8b90427bf690ea authored by Roland McGrath on 07 March 2008, 22:56:02 UTC, committed by Linus Torvalds on 08 March 2008, 03:05:58 UTC 
x86_64: make ptrace always sign-extend orig_ax to 64 bits
 
This makes 64-bit ptrace calls setting the 64-bit orig_ax field for a
32-bit task sign-extend the low 32 bits up to 64.  This matches what a
64-bit debugger expects when tracing a 32-bit task.

This follows on my "x86_64 ia32 syscall restart fix".  This didn't
matter until that was fixed.

The debugger ignores or zeros the high half of every register slot it
sets (including the orig_rax pseudo-register) uniformly.  It expects
that the setting of the low 32 bits always has the same meaning as a
32-bit debugger setting those same 32 bits with native 32-bit
facilities.

This never arose before because the syscall restart check never
matched any -ERESTART* values due to lack of sign extension.  Before
that fix, even 32-bit ptrace setting orig_eax to -1 failed to trigger
the restart check anyway.  So this was never noticed as a regression
of 64-bit debuggers vs 32-bit debuggers on the same 64-bit kernel.

Signed-off-by: Roland McGrath <roland@redhat.com>
[ Changed to just do the sign-extension unconditionally on x86-64,
  since orig_ax is always just a small integer and doesn't need
  the full 64-bit range ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 60d5bce
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Tip revision: 84c6f6046c5a2189160a8f0dca8b90427bf690ea authored by Roland McGrath on 07 March 2008, 22:56:02 UTC
x86_64: make ptrace always sign-extend orig_ax to 64 bits
Tip revision: 84c6f60
Kbuild 
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate asm-offsets.h
# 2) Check for missing system calls

#####
# 1) Generate asm-offsets.h
#

offsets-file := include/asm-$(SRCARCH)/asm-offsets.h

always  := $(offsets-file)
targets := $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s
clean-files := $(addprefix $(objtree)/,$(targets))

# Default sed regexp - multiline due to syntax constraints
define sed-y
	"/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"
endef
# Override default regexp for specific architectures
sed-$(CONFIG_MIPS) := "/^@@@/{s/^@@@//; s/ \#.*\$$//; p;}"

quiet_cmd_offsets = GEN     $@
define cmd_offsets
	(set -e; \
	 echo "#ifndef __ASM_OFFSETS_H__"; \
	 echo "#define __ASM_OFFSETS_H__"; \
	 echo "/*"; \
	 echo " * DO NOT MODIFY."; \
	 echo " *"; \
	 echo " * This file was generated by Kbuild"; \
	 echo " *"; \
	 echo " */"; \
	 echo ""; \
	 sed -ne $(sed-y) $<; \
	 echo ""; \
	 echo "#endif" ) > $@
endef

# We use internal kbuild rules to avoid the "is up to date" message from make
arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c FORCE
	$(Q)mkdir -p $(dir $@)
	$(call if_changed_dep,cc_s_c)

$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
	$(Q)mkdir -p $(dir $@)
	$(call cmd,offsets)

#####
# 2) Check for missing system calls
#

quiet_cmd_syscalls = CALL    $<
      cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags)

PHONY += missing-syscalls
missing-syscalls: scripts/checksyscalls.sh FORCE
	$(call cmd,syscalls)
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