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powerpc: Enable execve syscall exit tracepoint

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commit ec6d0dde71d760aa60316f8d1c9a1b0d99213529 upstream.

On execve[at], we are zero'ing out most of the thread register state
including gpr[0], which contains the syscall number. Due to this, we
fail to trigger the syscall exit tracepoint properly. Fix this by
retaining gpr[0] in the thread register state.

Before this patch:
  # tail /sys/kernel/debug/tracing/trace
	       cat-123     [000] .....    61.449351: sys_execve(filename:
  7fffa6b23448, argv: 7fffa6b233e0, envp: 7fffa6b233f8)
	       cat-124     [000] .....    62.428481: sys_execve(filename:
  7fffa6b23448, argv: 7fffa6b233e0, envp: 7fffa6b233f8)
	      echo-125     [000] .....    65.813702: sys_execve(filename:
  7fffa6b23378, argv: 7fffa6b233a0, envp: 7fffa6b233b0)
	      echo-125     [000] .....    65.822214: sys_execveat(fd: 0,
  filename: 1009ac48, argv: 7ffff65d0c98, envp: 7ffff65d0ca8, flags: 0)

After this patch:
  # tail /sys/kernel/debug/tracing/trace
	       cat-127     [000] .....   100.416262: sys_execve(filename:
  7fffa41b3448, argv: 7fffa41b33e0, envp: 7fffa41b33f8)
	       cat-127     [000] .....   100.418203: sys_execve -> 0x0
	      echo-128     [000] .....   103.873968: sys_execve(filename:
  7fffa41b3378, argv: 7fffa41b33a0, envp: 7fffa41b33b0)
	      echo-128     [000] .....   103.875102: sys_execve -> 0x0
	      echo-128     [000] .....   103.882097: sys_execveat(fd: 0,
  filename: 1009ac48, argv: 7fffd10d2148, envp: 7fffd10d2158, flags: 0)
	      echo-128     [000] .....   103.883225: sys_execveat -> 0x0

Cc: stable@vger.kernel.org
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Tested-by: Sumit Dubey2 <Sumit.Dubey2@ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220609103328.41306-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Naveen N. Rao 2022-06-09 16:03:28 +05:30 committed by Greg Kroah-Hartman
parent e0701f150b
commit b623297932
1 changed files with 1 additions and 1 deletions
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2
arch/powerpc/kernel/process.c
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@ -1719,7 +1719,7 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
tm_reclaim_current(0);
#endif
memset(regs->gpr, 0, sizeof(regs->gpr));
memset(&regs->gpr[1], 0, sizeof(regs->gpr) - sizeof(regs->gpr[0]));
regs->ctr = 0;
regs->link = 0;
regs->xer = 0;