[PATCH v7 2/2] ARM: ftrace: Add MODULE_PLTS support

[Florian Fainelli]

On 1/27/2021 3:09 AM, Alexander A Sverdlin wrote:
> From: Alexander Sverdlin <alexander.sverdlin at nokia.com>
> 
> Teach ftrace_make_call() and ftrace_make_nop() about PLTs.
> Teach PLT code about FTRACE and all its callbacks.
> Otherwise the following might happen:
> 
> ------------[ cut here ]------------
> WARNING: CPU: 14 PID: 2265 at .../arch/arm/kernel/insn.c:14 __arm_gen_branch+0x83/0x8c()
> ...
> Hardware name: LSI Axxia AXM55XX
> [<c0314a49>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14)
> [<c03115e9>] (show_stack) from [<c0519f51>] (dump_stack+0x81/0xa8)
> [<c0519f51>] (dump_stack) from [<c032185d>] (warn_slowpath_common+0x69/0x90)
> [<c032185d>] (warn_slowpath_common) from [<c03218f3>] (warn_slowpath_null+0x17/0x1c)
> [<c03218f3>] (warn_slowpath_null) from [<c03143cf>] (__arm_gen_branch+0x83/0x8c)
> [<c03143cf>] (__arm_gen_branch) from [<c0314337>] (ftrace_make_nop+0xf/0x24)
> [<c0314337>] (ftrace_make_nop) from [<c038ebcb>] (ftrace_process_locs+0x27b/0x3e8)
> [<c038ebcb>] (ftrace_process_locs) from [<c0378d79>] (load_module+0x11e9/0x1a44)
> [<c0378d79>] (load_module) from [<c037974d>] (SyS_finit_module+0x59/0x84)
> [<c037974d>] (SyS_finit_module) from [<c030e981>] (ret_fast_syscall+0x1/0x18)
> ---[ end trace e1b64ced7a89adcc ]---
> ------------[ cut here ]------------
> WARNING: CPU: 14 PID: 2265 at .../kernel/trace/ftrace.c:1979 ftrace_bug+0x1b1/0x234()
> ...
> Hardware name: LSI Axxia AXM55XX
> [<c0314a49>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14)
> [<c03115e9>] (show_stack) from [<c0519f51>] (dump_stack+0x81/0xa8)
> [<c0519f51>] (dump_stack) from [<c032185d>] (warn_slowpath_common+0x69/0x90)
> [<c032185d>] (warn_slowpath_common) from [<c03218f3>] (warn_slowpath_null+0x17/0x1c)
> [<c03218f3>] (warn_slowpath_null) from [<c038e87d>] (ftrace_bug+0x1b1/0x234)
> [<c038e87d>] (ftrace_bug) from [<c038ebd5>] (ftrace_process_locs+0x285/0x3e8)
> [<c038ebd5>] (ftrace_process_locs) from [<c0378d79>] (load_module+0x11e9/0x1a44)
> [<c0378d79>] (load_module) from [<c037974d>] (SyS_finit_module+0x59/0x84)
> [<c037974d>] (SyS_finit_module) from [<c030e981>] (ret_fast_syscall+0x1/0x18)
> ---[ end trace e1b64ced7a89adcd ]---
> ftrace failed to modify [<e9ef7006>] 0xe9ef7006
> actual: 02:f0:3b:fa
> ftrace record flags: 0
> (0) expected tramp: c0314265
> 
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin at nokia.com>

Tested-by: Florian Fainelli <f.fainelli at gmail.com>
-- 
Florian